Targeting Fusobacterium nucleatum in colorectal cancer: therapeutic strategies and future directions

Abstract

There is growing evidence that Fusobacterium nucleatum, a Gram-negative anaerobic bacterium found in the gut and oropharynx, is a key player in the pathogenesis of colorectal cancer (CRC), by promoting tumor progression, immune evasion, and drug resistance. Despite the effectiveness of antibiotic regimens in reducing F. nucleatum abundance, concerns about antimicrobial resistance and gut dysbiosis limit the use of these drugs for a long period of time. Antimicrobial peptides (AMPs), bacteriophage therapy, and immune-based interventions all offer promising alternatives to conventional treatments. Checkpoint inhibitors and microbiome-based immunotherapy may also enhance antitumor immunity by alleviating F. nucleatum-induced immunosuppression. Furthermore, multimodal strategies, including dietary interventions and engineered probiotics, can help manage F. nucleatum-associated CRC holistically. It has been shown that probiotics can modulate gut microbiota composition and reduce F. nucleatum colonization by using strains of Lactobacillus and Bifidobacterium. This has led to improved outcomes for CRC patients by targeting this bacterium. In addition, preclinical evidence indicates that certain peptide-based antimicrobials can target F. nucleatum biofilms, though their specificity for pathogenic over commensal bacteria. Phage therapy, for instance, selectively targets the bacterium without harming others. But, to ensure efficacy and safety, clinical trials and mechanistic studies should be undertaken to optimize these therapeutic strategies. Understanding F. nucleatum’s role in CRC and refining targeted interventions can help researchers develop innovative strategies to prevent and treat CRC. The purpose of this review is to examine current and emerging approaches to combating F. nucleatum in CRC, with a particular focus on probiotics, antibiotics, and alternative therapies.

Introduction

Colorectal cancer (CRC) is one of the major global health concern, ranking third in incidence and second in cancer-related mortality worldwide, with an estimated 10 million deaths reported in 2020 [1]. Its burden is expected to increase significantly over the coming decade, especially in upper-middle-income countries, which account for over 45% of new cases [2]. While early screening programs have stabilized incidence rates in older adults, CRC is increasingly diagnosed in younger individuals, often at advanced stages due to misdiagnosis or delayed medical care [3]. Risk factors for CRC include chronic inflammation, family history, poor diet, physical inactivity, smoking, alcohol consumption, and aging [4]. These trends underscore the need for early detection and prevention strategies, particularly among younger populations.

Among the bacterial species implicated in CRC (Table 1), Fusobacterium nucleatum has emerged as a key contributor to tumor development and progression. Although it is typically an oral commensal, F. nucleatum is frequently detected in colorectal tumors and stool samples from CRC patients. It reaches the gut via hematogenous spread or ingestion and adheres to tumor tissues using surface proteins such as Fibroblast activating protein 2 (Fap2) and Fusobacterium adhesin A (FadA), which bind to tumor-associated glycans and E-cadherin, respectively [5, 6]. These adhesins facilitate colonization, immune evasion, and biofilm formation, allowing F. nucleatum to persist in the tumor microenvironment. In addition, this bacterium has been linked to chemotherapy resistance and poor prognosis in CRC. It interferes with apoptosis and promotes autophagy, inflammation, and immune modulation, enabling cancer cells to survive treatment [7]. It also disrupts the composition and function of the gut microbiota, which may further impair drug metabolism and reduce therapeutic efficacy [8]. These findings highlight F. nucleatum not only as a driver of carcinogenesis but also as a potential biomarker and therapeutic target. Given these multifaceted roles, F. nucleatum is now considered a potential therapeutic target in CRC.

Table 1.

Bacteria involved in the pathogenesis of CRC

Bacterium	Proposed Mechanism(s)	Ref.
Escherichia coli (pks + strains)	Production of colibactin, genotoxin-induced DNA damage	[207]
Bacteroides fragilis (ETBF)	Production of BFT toxin, modulation of immune response, promotion of Th17 inflammation	[208]
Peptostreptococcus anaerobius	Activation of PI3K-Akt signaling, cholesterol biosynthesis	[209]
Parvimonas micra	Associated with tumor progression, not fully understood	[210]
Streptococcus gallolyticus	Enhancement of cell proliferation, possible direct oncogenic effects	[211]
Enterococcus faecalis	Induction of DNA damage via reactive oxygen species	[212]
Helicobacter pylori	Controversial in CRC, more established in gastric cancer; chronic inflammation	[213]

In this review, we critically evaluate current and emerging strategies to combat F. nucleatum in CRC. We explore antimicrobial, immunological, probiotic, and dietary approaches that aim to eliminate or neutralize its effects. By assessing these interventions and their mechanisms, we aim to support the development of targeted therapies that improve clinical outcomes for CRC patients.

F. nucleatum in CRC

Microbiological characteristics

F. nucleatum is a Gram-negative, anaerobic, non-spore-forming bacterium commonly found in the oral and gastrointestinal microbiota. It has a spindle-shaped morphology and plays a key role in biofilm formation, particularly in the oral cavity [9]. Based on DNA-DNA hybridization, protein profiles, and 16–23 S ITS region sequencing, it is classified into multiple subspecies with distinct phenotypic traits [10]. F. nucleatum primarily relies on amino acid fermentation for energy and requires peptides for growth, although it can store glucose as a polysaccharide under certain conditions [11]. Its metabolic flexibility enables it to thrive in complex polymicrobial communities, especially in nutrient-rich environments such as dental plaque [12]. As a “bridge” organism, it facilitates the adhesion and coaggregation of other bacteria, contributing to periodontal disease and enhancing virulence within polymicrobial biofilms [13, 14].

Beyond its oral pathogenicity, F. nucleatum has been linked to various systemic infections, including appendicitis, chorioamnionitis, osteomyelitis, pericarditis, and brain abscesses [15]. It can translocate from the oral cavity to extraoral sites, including the placenta, where it may trigger inflammation and adverse pregnancy outcomes such as preterm labor, fetal growth restriction, and miscarriage [16]. Recent studies have also associated F. nucleatum with several malignancies beyond the oral cavity, including colorectal, breast, gastric, and esophageal cancers, as well as with chronic inflammatory and cardiovascular diseases [17]. Its ability to modulate host immunity and contribute to systemic inflammation makes it a pathogen of increasing clinical importance (Table 2).

Table 2.

Fusobacterium nucleatum virulence factors and their roles in CRC

Virulence factor	Function / mechanism	Role in CRC	Notes	Ref.
FadA	Binds to E-cadherin on host epithelial cells	Activates β-catenin signaling → promotes cell proliferation, inflammation, tumor growth	Well-characterized in CRC models	[214]
Fap2	Gal-GalNAc-binding lectin	Inhibits NK cell activity via TIGIT interaction; enables immune evasion	Also promotes bacterial adherence to tumor tissue	[215]
RadD	Outer membrane adhesin	Mediates inter-bacterial aggregation and biofilm formation	Supports colonization and dysbiosis	[216]
LPS	TLR4 agonist	Triggers pro-inflammatory responses; contributes to tumor-promoting microenvironment	Common to Gram-negative bacteria	[217]
CbpF	Binds CEACAM1 on immune cells	May modulate immune signaling, contributing to immune tolerance	Recently discovered; under investigation	[218]
OMVs	Deliver virulence proteins and RNA	Can induce DNA damage, inflammation, and immune modulation	Emerging evidence in tumor microenvironment	[219]
Butyrate Production	SCFAs with dual roles	Can support tumor cell survival at certain concentrations	Function depends on context and concentration	[220]

Association with CRC

• A. Immune modulation and immune evasion.
  • Suppression of anti-tumor immunity:
    • F. nucleatum promotes the recruitment of myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), dendritic cells (DCs), and tumor-associated neutrophils (TANs), which dampen effective T-cell responses and foster a tumor-favorable microenvironment [18, 19].
    • It reduces tumor-infiltrating lymphocytes (TILs) and promotes T cell apoptosis via its outer membrane adhesins Fap2 and RadD, which bind to immune inhibitory receptors such as TIGIT on T and NK cells [20, 21].
    • Downregulation of CD8⁺ T cells and elevation of CD33⁺ MDSCs and CD163⁺ TAMs further exacerbate immune suppression [22, 23] (Fig. 1).
  • Macrophage polarization:
    • F. nucleatum skews macrophages toward an M2-like phenotype (F4/80⁺, CD206⁺), which promotes tumor growth by secreting anti-inflammatory cytokines (e.g., IL-10, TGF-β) via the TLR4/IL-6/STAT3/c-Myc cascade [24].
    • LPS and outer membrane vesicles (OMVs) from F. nucleatum induce production of IL-8 and IL-10, suppressing pro-inflammatory M1 macrophages [25].
• B. Inflammatory microenvironment and cytokine modulation.
  • Cytokine secretion and tumor promotion:
    • Induces secretion of IL-6, IL-8, IL-17, CXCL1, and CCL20 through TLR4 and PRR signaling [26].
    • miR-1322 and miR-5692a are downregulated in CRC, enhancing pro-metastatic cytokines and epithelial-to-mesenchymal transition (EMT) through the NF-κB and ERK pathways [27, 28].
    • F. nucleatum-derived small extracellular vesicles (F. nucleatum-EVs) stimulate tumor growth and metastasis by activating TLR4 [29].
• C. Metastatic cascade and EMT activation.
  • Adhesion and EMT promotion:
    • Adhesins like FadA and Fap2 enhance EMT, increasing cell invasiveness [30].
    • Blocking these adhesins using knockouts or sugar inhibitors reduces metastasis-associated migration [31].
• D. Gut dysbiosis and microbiome disruption.
  • Alteration of microbial ecology:
    • F. nucleatum disrupts gut microbial balance, creating dysbiosis that fuels chronic inflammation, epithelial barrier dysfunction, and carcinogenesis [32, 33].
    • In Dextran Sulfate Sodium (DSS) mouse models, F. nucleatum increased proinflammatory cytokines (IL-1β, TNF-α) and decreased IL-10, leading to apoptosis of intestinal epithelial cells and altered bile acid metabolism [34].
  • Dysbiosis as a diagnostic marker:
    • Early presence of F. nucleatum predicted microbial changes in inflammatory bowel disease (IBD) [35].
    • Its abundance correlated with changes in microbial phyla such as Gemmatimonadetes (positive) and Tenericutes, Euryarchaeota (negative) [8].

Fig. 1.

F. nucleatum-mediated tumor progression and immune modulation. Created in BioRender. Aliramezani, A. (2025) https://BioRender.com/1fcyvei

Impact on tumor progression, metastasis, and patient prognosis

Tumor progression

• The bacterium stimulates inflammatory cytokine production (e.g., IL-6, IL-8, TNF-α) through TLR4/NF-κB activation and promotes immune cell recruitment that paradoxically supports tumor growth [36, 37].

• F. nucleatum induces oxidative stress, downregulates DNA repair enzymes like NEIL2, and disrupts mismatch repair via MSH3 mislocalization. These lead to genomic instability, microsatellite alterations, and hypermethylation of tumor suppressor genes [38, 39]. Increased γH2AX expression and recruitment of DNA methyltransferases (DNMTs) contribute to these mutagenic effects.

• F. nucleatum produces formate, an oncometabolite that activates the AhR pathway and promotes CRC cell stemness, glutamine dependency, and invasiveness [40, 41]. It also enhances Th17 cell recruitment and IL-17 secretion, fostering chronic inflammation. Short-chain fatty acids (SCFAs) like butyrate and acetate interact with free fatty acid receptor 2 (FFAR2) to modulate immune responses and promote epithelial signaling favorable to tumor growth [42].

• As a pathobiont, F. nucleatum thrives in dysbiotic conditions and contributes to microbial imbalance. It impairs epithelial barriers, increases permeability, and facilitates systemic inflammation through LPS and other products [34, 35]. Its abundance correlates with altered microbial diversity and supports a pro-carcinogenic microbial network [8].

Metastasis

• Disruption of m6A RNA methylation and stabilization of oncogenic transcripts: Recent studies have shown that F. nucleatum facilitates metastatic progression by suppressing N6-methyladenosine (m6A) RNA modifications. It downregulates the methyltransferase METTL3 via suppression of the Hippo pathway and activation of YAP, leading to the repression of the transcription factor FOXD3 [43]. As a result, oncogenic transcripts such as KIF26B become stabilized due to impaired m6A-dependent degradation mechanisms, promoting CRC cell invasion and migration. This is further exacerbated by F. nucleatum’s inhibition of the m6A reader YTHDF2, which prevents the clearance of oncogenic mRNAs. Clinically, elevated KIF26B expression in CRC tissues correlates with poor patient survival and inversely associates with METTL3 levels [44].

• Immune modulation and cytokine-induced inflammation: F. nucleatum stimulates the expression of pro-inflammatory cytokines including IL-6, IL-12, IL-17 A, TNF-α, and IFN-γ, establishing an immunosuppressive environment. These cytokines promote the recruitment of MDSCs, Th17 cells, and NK cells to the liver, impairing effective anti-tumor immunity and enhancing metastatic potential [45]. Simultaneously, F. nucleatum-induced dysbiosis enriches CRC-promoting bacteria, such as Enterococcus and Escherichia/Shigella, which further amplify inflammatory signaling and support tumor cell proliferation and metastasis [46, 47].

• Induction of EMT via the KRT7-AS/KRT7 axis: In addition to immune modulation, F. nucleatum drives EMT through upregulation of the long non-coding RNA KRT7-AS and its corresponding protein-coding gene KRT7. This upregulation is mediated via the NF-κB signaling pathway, enhancing CRC cell motility and metastatic capacity. Silencing KRT7-AS reduces lung metastasis in murine models, confirming its functional role.

• Metabolic reprogramming through CYP2J2 and 12,13-EpOME: F. nucleatum activates the TLR4/Keap1/NRF2 pathway, resulting in upregulation of cytochrome P450 2J2 (CYP2J2) and increased production of the epoxide 12,13-EpOME. These metabolites enhance EMT and CRC cell invasiveness and are associated with poor clinical outcomes and aggressive disease phenotypes [48].

• Autophagy activation and epithelial integrity disruption: The bacterium also enhances autophagy through the upregulation of CARD3, contributing to metastatic behavior. Increased expression of autophagy markers (LC3-II and Beclin1) and decreased E-cadherin expression have been observed in F. nucleatum-infected CRC cells. These changes support EMT, invasion, and systemic dissemination. Furthermore, activation of the TLR4/Keap1/NRF2 axis reinforces these effects by promoting pro-metastatic metabolic changes [49] (Table 3).

Table 3.

Molecular mechanisms of Fusobacterium nucleatum pro-tumorigenicity and pro-metastasis

Mechanism	The specific role Fusobacterium nucleatum plays in CRC	Meta- stasis	Tumori- genesis	Ref
Suppression of the immune response	Increasing MDSCs and inhibiting T cell proliferation in a selective manner.	x	x	[221, 222]
	Induces S100A9 expression and activates M2 macrophages by recognizing toll-like receptor 4 (TLR4).	x	x	[24]
	Promotes Foxp3 + regulatory T cell differentiation while inhibiting effector T cell activity.		x	[50]
	Binds to TIGIT through Fap2, enabling tumor cells to evade immune attack.		x	[223]
	Promotes an inflammatory environment by activating NF-κB, CREB, and extracellular signal-regulated kinases (ERKs).		x	[36, 224]
	Promotes the release of pro-inflammatory cytokines in the liver, fostering a chronic inflammatory state while simultaneously creating an immunosuppressive microenvironment.	x		[45]
Promotion of oncogenic gene expression	Promotes tumor cell proliferation by upregulating microRNA-21 expression.		x	[225]
	Enhances cell proliferation by upregulating lncRNA ENO1-IT1 transcription, leading to a reduced pH in the tumor microenvironment (TME).		x	[226]
	Elevates miR-1246, miR-92b-3p, and miR-27a-3p expression to promote tumor invasion.	x	x	[27]
	Promotes HIF-1α enrichment and H3K27Ac acetylation thereby promoting angiogenesis.	x	x	[227]
	Upregulates KRT7-AS and KRT7 expression, promoting tumor cell migration and metastasis.	x		[49]
	Upregulates long noncoding RNA EVADR and promotes CYP2J2 transcription for EMT.	x		[48, 228]
	Induces intercellular adhesion molecule 1 expression.	x		[229]
	Enhances the expression of autophagy-related protein genes to drive tumor progression.	x		[230]
	Suppresses the expression of genes encoding related proteins and decreases m6A levels, facilitating tumor invasion.	x		[43]
DNA damage	Induces reactive oxygen species (ROS) generation, leading to CpG methylation, microsatellite instability-high (MSI-H), and DNA damage.		x	[38, 231]
	Upregulates the level of NEL2 which in turn accumulates DSBs.		x	[39]
Metabolite effect	Formate production enhances the renewal of tumor stem cells.		x	[41]
	Generation of succinic acid mediates inflammatory response.		x	[232, 233]
	SCFAs and butyrate inhibit anti-tumor immune cells and promote tumor angiogenesis.		x	[234]
Toxicokinetic effect	FadA drives the expression of oncogenic factors by activating the β-catenin/E-cadherin/Wnt signaling pathway.		x	[235]
	Fap2 binding to Gal-GalNAc triggers lymphocyte apoptosis and interacts with ITIM domains.		x	[20]
	lipopolysaccharides (LPS) activaties the TLR4/p-PAK1/p-catenin protein S675 signaling pathway to promote tumor cell proliferation.		x	[224]

Patient prognosis

• A.Prevalence and prognostic significance.

  F. nucleatum is increasingly detected in CRC tissues at higher abundance compared to adjacent normal mucosa, raising questions about its role in disease severity, drug resistance, and patient survival. Mima et al., reported that patients with high intratumoral F. nucleatum DNA levels had a 58% increased risk of CRC-specific mortality, independent of other tumor molecular characteristics such as MSI, CIMP, and BRAF mutations [50]. Tumors colonized by F. nucleatum also tended to exhibit poor differentiation and advanced stages, both indicative of more aggressive disease progression. A meta-analysis by Gethings-Behncke et al., supports these findings, reporting that F. nucleatum is significantly more abundant in CRC samples compared to healthy controls, both in tissue and stool. It is associated with worse overall survival (pooled HR: 1.87; 95% CI: 1.12–3.11). These findings strengthen its role as a prognostic biomarker, possibly by sustaining a pro-inflammatory, immunosuppressive tumor microenvironment [51].

• B.Molecular subtypes and genetic associations.

  Epidemiological and molecular studies indicate a selective association between F. nucleatum and specific CRC subtypes. The bacterium is enriched in:

  • MSI-high tumors, likely due to its role in chronic inflammation and immune suppression.
  • CIMP-high tumors, where it may promote hypermethylation of key tumor suppressor genes like hMLH1.
  • BRAF^V600E mutant CRCs, reinforcing oncogenic MAPK signaling.

  Conversely, an inverse relationship exists between F. nucleatum and TP53 mutations, commonly found in chromosomal instability (CIN)-type tumors. These findings suggest that F. nucleatum preferentially colonizes epigenetically unstable tumors with immunoevasive properties [52, 53].

• C. Tumor abundance and metastatic potential.

  Using RNA-seq and qPCR, Castellarin et al., showed a 415-fold overabundance of F. nucleatum in CRC tumors compared to adjacent tissues. High bacterial load was significantly associated with regional lymph node metastases, and patients harboring high levels had poorer overall survival (26.4 vs. 30.7 months; adjusted HR: 1.69, p = 0.034). The bacterium’s presence correlated with increased mutation rates in genes like AMER1, ATM, and TGF-β pathway components, as well as higher rates of C→T and G→A nucleotide transitions [54].

• D.Activation of oncogenic signaling.

  The bacterium directly activates Wnt/β-catenin signaling via its FadA adhesin binding to host E-cadherin, upregulating annexin A1 (ANXA1). This facilitates a positive feedback loop, promoting further expression of oncogenes like cyclin D1, cell proliferation, and metastasis. This “two-hit” model, as proposed by Rubinstein et al., suggests that while genetic mutations initiate CRC, F. nucleatum drives disease progression in already-transformed cells [55].

Antimicrobial strategies

One of the key steps in the development of CRC is the ability of F. nucleatum to form biofilms on the colonic mucosa. Targeting F. nucleatum biofilms with antibiotic therapy, such as metronidazole or combination regimens, could disrupt these microbial aggregates, reduce bacterial load, and mitigate CRC progression [56]. A variety of factors determine the effectiveness of antibiotics against F. nucleatum, including the strain, the resistance mechanisms, and the site of infection. It is generally susceptible to a range of antibiotics, including some beta-lactams as penicillin and cephalosporins, as well as metronidazole, which is frequently the drug of choice for the treatment of anaerobic bacteria due to its potent activity against them [57]. Additionally, carbapenems, fluoroquinolones and clindamycin showed good efficacy in some strains of this bacterium, but in some cases, it may encounter resistance. The level of clindamycin resistance varied by region, ranging from 6.7 to 25% for Fusobacterium spp [58]. In addition, the results of various studies indicated that resistance rates for fluoroquinolones ranged from 7 to 50%. Increasing reports of penicillinase and beta-lactamase-producing F. nucleatum isolates (4–17% or in some reports 50% in Ireland) underline the importance of susceptibility testing to guide therapy [59]. The empirical treatment study conducted by Kim et al., on different species of Fusobacterium at a tertiary-care hospital in Korea showed all F. nucleatum isolates were susceptible to the antimicrobial agents tested [60]. However, an evaluation of the antimicrobial susceptibility of F. nucleatum to different antibiotics in Brazil showed that only metronidazole and erythromycin were effective against the isolate [61].

A treatment that targets F. nucleatum effectively reduces its abundance, which alleviates its immunosuppressive properties. This reduction helps to restore immune surveillance and re-sensitizes tumors to immunotherapy, enhancing the overall therapeutic response and potentially improving patient outcomes [62]. Wang et al., investigated the study regarding how metronidazole could influence F. nucleatum in mice and prevent CRC metastasis. It reduced tumor growth and occurrence in mice, diminished the malignant degree of reduced liver metastases and Ki67-positive cells (CRLM), and suppressed liver metastasis in CRC mice by regulating intestinal flora structure, which altered intestinal characteristic flora [63]. The library screened by Su et al., successfully identified higenamine as an antibacterial hit against F. nucleatum. A mechanism study revealed that compound 7c impairs the integrity of biofilms and cell walls, which represents a promising starting point for the development of novel anti-F nucleatum agents. Chemoprevention with aspirin can be used to prevent CRC, with its effects on bacterial growth and virulence gene expression similarly studied as many other drugs [64]. According to Brennan et al., aspirin and salicylic acid alter F. nucleatum strain Fn7-1 growth in culture, and aspirin kills both actively growing and stationary strains. Fn7-1 is orally inoculated daily into ApcMin/+ mice to test whether aspirin modulation of F. nucleatum is relevant in vivo, and we demonstrate that supplementing chow with aspirin inhibited colonic tumor cell growth [42]. In adiition, Deng et al., found in a mouse model of CRC; non-absorbable antibiotics inhibited liver metastasis compared with a control group. Deoxycholic acid (DCA) concentrations in feces and liver tissues decreased significantly after non-absorbable antibiotic treatment. Also, mice treated with non-absorbable antibiotics lost the ability to convert cholic acid (CA) to DCA via 7-dehydroxylation and consequently, DCA accelerated CRC cell proliferation and metastasis in vitro and in vivo [65].

Probiotic interventions

Many diseases are associated with imbalance in the gastrointestinal microbiome. Changes in the number and composition of beneficial bacteria inhabiting the intestines are among the most common characteristics of diseases such as Crohn’s disease, ulcerative colitis, respiratory infection, and autism [66]. Although the underlying mechanism of probiotics in modulating gut microbiota remains unclear, probiotics modulate gut microbiota through several complex mechanisms, including competitive exclusion of pathogens, enhancement of the gut barrier function, and modulation of innate and adaptive immune systems [67]. One of the primary mechanisms by which probiotics affect the gut microbiome is isolating harmful bacteria. They produce antimicrobial compounds, such as bacteria, which can protect the intestinal environment by inhibiting the growth of pathogens. In addition, probiotics strengthen the gut mucosal barrier by enhancing mucus production and tightening tight junctions, so that harmful bacteria are unable to penetrate through this opened door into intestinal lining [68] (Table 4).

Table 4.

CRC risk mitigation by probiotic strains that target Fusobacterium nucleatum

Probiotic Strain	Mechanism Against Fusobacterium nucleatum	Ref
Lactobacillus rhamnosus GG	Inhibits F. nucleatum growth, reduces inflammation	[236]
Bifidobacterium breve	Restores gut microbiota, reduces NF-κB signaling	[237]
Lactobacillus acidophilus	Produces bacteriocins that kill F. nucleatum	[238]
Bifidobacterium longum	Enhances gut barrier function, reduces inflammation	[239]
Faecalibacterium prausnitzii	Produces butyrate, reduces inflammation and tumor growth	[101]
Saccharomyces boulardii	Maintain intestinal barrier integrity and reduce inflammation associated with F. nucleatum overgrowth	[75]

Probiotics alter gut bacteria composition by enhancing the aggregate amount of beneficial bacteria, such as Bifidobacterium, which inhibits the growth of F. nucleatum. It has been demonstrated that lactic acid is produced by L. rhamnosus GG and B. longum, lowering gut pH and creating a hostile environment for F. nucleatum. Additionally, these strains compete with F. nucleatum for mucosal adhesion sites, reducing its ability to colonize the gut [69]. Mechanistic studies have confirmed their potential in enhancing mucosal immunity by demonstrating the importance of these probiotics. In order to achieve this, they upregulate the production of anti-inflammatory cytokines while downregulating pro-inflammatory responses, especially in CRC [70]. It is demonstrated in vivo that probiotic treatment can reduce tumor burden and colonization of F. nucleatum by up to 40%. The findings have been confirmed by several preclinical studies, confirming the potential therapeutic value of these probiotics. A probiotic strain engages F. nucleatum during competition by inhibiting its adhesion to epithelial cells. It inhibits the growth of biofilms, thereby limiting the oncogenic effects of F. nucleatum, including inflammation induction, epithelial-mesenchymal transition, and tumor proliferation. These data are supported by in vitro studies, which have proved the efficacy of L. acidophilus and B. bifidum, which prevented F. nucleatum biofilm formation and reduced inflammatory cytokines [71, 72].

Another critical point in preclinical data involves the role of probiotics in enhancing gut barrier function. It has been shown that probiotic strains such as B. longum are capable of increasing the expression of tight junction proteins such as occludin and claudin. The reinforcement of the gut barrier prevents F. nucleatum from crossing over the epithelium, preventing systemic inflammation and reduces the downstream effects of its virulence factors, which contribute to CRC progression [73]. In addition, the study found that the gut barrier function had been enhanced as mucin production increased. This protein is also key to preserving gut homeostasis and inhibit bacterial translocation. Patients with CRC who took a probiotic supplement containing L. acidophilus and B. bifidum had a significant reduction in F. nucleatum counts in their stool samples, which led to improvements in quality of life. Furthermore, probiotics improved immune function in CRC patients by stimulating the activity of NK cells by secreting AMPs that target the F. nucleatum [74].

A study conducted by Zeng et al., showed a beneficial effect of Saccharomyces cerevisiae JKSP39 on a F. nucleatum- and DSS-induced colitis mouse model. S. cerevisiae supplementation increased body weight and anti-inflammatory cytokines (IL-4 and IL-10) expression, while reducing disease activity index and proinflammatory cytokine expression in mice undergoing experimental colitis in comparison with mice in a colitis model. In the S. cerevisiae group, tight junction proteins and the number of goblet cells per crypt were significantly higher, indicating that the gut barrier had been repaired well. Finally, F. nucleatum-DSS-induced colitis can be ameliorated by S. cerevisiae because it decreases the level of reactive oxygen species in the colon such as total superoxide dismutase, myeloperoxidase, H2O2, catalase, and malondialdehyde, therefore inhibits endoplasmic reticulum stress, and regulates gut microbiota [75].

In vitro screening for gut-derived strains that exhibit anti-F. nucleatum activity revealed Streptococcus salivarius DPC6487 as a potential candidate. It has been demonstrated that S. salivarius DPC6487 produces Nisin G and can control F. nucleatum DSM15643 in an ex vivo model colonic environment while exerting minimal impact on the microbiota around it. A gut-derived S. salivarius strain proved capable of producing this bacteriocin, exhibiting narrow-spectrum activity, and exhibiting anti-F. nucleatum activity in a model colonic environment, indicating that this strain warrants further study for its potential as a probiotic [76]. The study by Wang et al., showed Lactiplantibacillus plantarum HNU082 inhibited F. nucleatum growth and alleviated the inflammatory response introduced by the invasion. In a mouse model, L. plantarum HNU082, which had a negative correlation with F. nucleatum, was shown to maintain intestinal microbiome homeostasis and to stimulate the production of beneficial metabolites, which reduced the expression of inflammatory cytokines. Probiotic intervention for F. nucleatum antagonism may prevent colorectal cancer at an early stage according to the results of this study [77].

The Lawrence et al., study tested fecal samples of healthy donors for antimicrobial properties of probiotics producing bacteriocins. It has been demonstrated in vitro that Streptococcus salivarius DPC6993 has a narrow spectrum of antimicrobial activity against F. nucleatum. Based on an in silico analysis of the S. salivarius DPC6993 genome, two bacteriocin genes have been identified: salivaricin A5 and salivaricin B. The number of F. nucleatum dropped significantly in samples inoculated with S. salivarius DPC6993 and F. nucleatum DSM15643 simultaneously after 6 h in a colon fermentation model. A diversity analysis indicated that S. salivarius DPC6993 did not exert any significant impact on the microbiota in the surrounding environment [78]. Taken together, Probiotics offer potential for prevention, adjunctive therapy, or even microbiota-modulating treatment options in CRC by targeting F. nucleatum. However, further research is necessary to identify the most effective strains and therapeutic regimes for optimal clinical outcomes.

Prebiotics and dietary interventions

Prebiotics play a major role in gut health by stimulating the growth and activity of beneficial gut microbes. These non-digestible food ingredients provide selective nourishment for beneficial gut bacteria, maintaining a balanced microbiome and thus promoting overall gastrointestinal health [79]. The impact of prebiotics on gut health has been increasingly recognized for their ability to modify gut microbiota composition in favor of health-promoting microorganisms, which play essential roles in digestion, immune regulation, and even mood regulation. Maintaining the integrity of the gut barrier and preventing diseases related to the gut, mainly depend on a healthy and balanced gut microbiota [80]. The fermentation of prebiotics in the colon leads to the production of SCFAs, particularly butyrate, propionate, and acetate, which have been shown to have profound health benefits. However, butyrate serves as the immune responses to reduce inflammation. In addition to SCFAs production, prebiotics enhance microbial diversity, which is associated with a healthier gut microbiome and improved resistance to pathogens [81]. The selective growth of beneficial microorganisms such as Bifidobacterium and Lactobacillus helps maintain a stable and functional gut microbiota by outcompeting pathogenic microbes. The health benefits of prebiotics extend beyond gut health [82]. Studies have shown they may affect metabolic health, immune function, and mental well-being. The modulation of the gut microbiota through prebiotics has been shown to improve immune responses by enhancing the production of regulatory T cells (Tregs) and promoting gut-associated lymphoid tissue (GALT) function. Prebiotics may also have neuroactive properties, potentially improving mood and cognitive function by modulating the gut microbiota, according to emerging research on the gut-brain axis [83].

Prebiotics typically include oligosaccharides, fibers, and certain plant-derived compounds. These can be found in a variety of foods such as onions, garlic, bananas, and whole grains, and can selectively stimulate the growth of specific microbiota. The most well-established prebiotics are oligosaccharides such as inulin, fructooligosaccharides (FOS), and galactooligosaccharides (GOS), widely consumed through foods and supplements [84]. Inulin, a fructan, is found in various plants, including chicory root, Jerusalem artichokes, and garlic. It has been shown to stimulate the growth of beneficial Bifidobacterium species and improve gut health by increasing the production of SCFAs like butyrate. Additionally, FOS and GOS, found in foods like onions, bananas, and legumes, enhance the growth of beneficial gut bacteria, improving gut microbiota composition and digestion [85]. Incorporating prebiotics into functional foods, dietary supplements, and beverages can enhance a prebiotic-rich diet. Various products, including prebiotic-enriched yogurts, fiber supplements, and beverages like kombucha, are designed to improve digestion and increase beneficial microbiota [86] (Table 5).

Table 5.

Prebiotics classification and characteristics

Category	Prebiotic	Chemical Structure	Production Method	Potential Benefits	Ref
Synthetic Prebiotics	Fructooligosaccharides (FOS)	Glucose and fructose units linked by β (2→1) glycosidic linkages	Enzymatic catalysis (fructosyltransferase) from sucrose	Improve mineral absorption, immunity, inhibit pathogens, prevent cancer, control diabetes	[240]
	Galactooligosaccharides (GOS)	Galactose and glucose bound by β (1→3) and β (1→4) linkages	Transgalactosylation of lactose using β-galactosidase	Increase bifidogenic activity, improve gut health	[79]
	Xylooligosaccharides (XOS)	Xylose units linked through β (1→4) bonds	Enzymatic hydrolysis of plant xylans	Positive effects on gut flora, non-carcinogenic, beneficial for digestion	[241]
	Soybean Oligosaccharides (SOS)	Galactose α-(1–6) linked to glucose	Derived from soybeans (stachyose, raffinose)	Modulate immune system, support gut flora, affect body weight	[242]
	Isomalto-oligosaccharides (IMO)	Glucose bonds by α (1→4) type	Enzymatic treatment of liquefied starch	Improve gastrointestinal flora, support gut health	[243]
	Fructans	fructose with β (2→1) linkage	Enzymatic hydrolysis using Fructozyme L	Modulate gut physiology to provide protection from pathogens, improve the level of glucose	[244]
	Guar gum	β-D-mannopyranosyl (1–4) linked with α-D-galactopyranosyl (1–6) residues	Enzymatic hydrolysis using cellulase	Improve cholesterol, glycemia	[245]
	Pectinoligosaccharides (POS)	(1–4)-α-D-GalA (galacturonic acid) -(1,2)-α-L-Rha	Enzymatic hydrolysis by pectinase	Anti-inflammatory effect	[246]
Natural Prebiotics	Dandelion Greens	Inulin, oligofructans	Naturally occurring in dandelion plant parts	Modulate Bifidobacteria, improve lipid metabolism and gut health	[247, 248]
	Chicory Roots	Inulin (fructan polymer)	Naturally occurring in chicory roots	Nourish probiotics, widely used in functional foods	[249, 250]
	Chia Seeds	High fiber content	Naturally occurring in chia seeds	Enhance gut health, increase mineral absorption	[251]
	Artichoke	Inulin and polyphenols	Naturally occurring in artichoke	Support beneficial gut microbes, antioxidant and hepatoprotective activities	[252]
	Garlic	FOS (fructans)	Naturally occurring in garlic	Selectively stimulate Bifidobacteria, anti-pathogenic effects	[253]
	Almonds	Dietary fiber, polyphenols	Naturally occurring in almond seeds	Improve gut microbiome, inhibit pathogenic bacteria, improve digestion	[254, 255]
	Flaxseeds	Soluble fiber, high-quality protein	Naturally occurring in flaxseeds	Influence gut environment, enhance beneficial gut bacteria, liver health	[256]
	Onions	FOS, soluble carbohydrates	Naturally occurring in onions	Improve gut microflora, support digestion	[257]
	Oats	β-glucan (soluble fiber)	Naturally occurring in oats	Support gut health, regulate blood sugar, assist in managing obesity and hypertension	[258]
	Barley	Polysaccharides, β-glucans	Naturally occurring in barley	Regulate cholesterol, blood sugar, improve immunity	[259]

Impact on F. nucleatum

Using prebiotics, a fermented food component that alters the gut microbiota in a specific way, is a promising method of combating F. nucleatum colonization. Prebiotic supplementation may affect F. nucleatum levels, either directly or indirectly, according to emerging research [87]. A randomized clinical trial assessed the effects of xylooligosaccharides (XOS), a prebiotic produced from plant fibers, on patients undergoing chemotherapy for colorectal cancer. The study hypothesizes that XOS supplementation modulates gut microbiota composition by promoting beneficial bacteria like Bifidobacterium and Lactobacillus, which indirectly suppress pathogenic bacteria like F. nucleatum. Prebiotics like XOS may improve chemotherapy tolerability and outcome by fostering a healthier gut microbial ecosystem, thereby reducing F. nucleatum abundance [88]. The study’s results are still pending, but it demonstrates the growing recognition of prebiotics as adjuncts for managing CRC. Additionally, Cassotta et al., investigated the role of diet in influencing F. nucleatum abundance in a cross-sectional study. They investigated dietary patterns and their association with fecal F. nucleatum levels in a cohort of healthy adults. Based on findings, diets rich in fruits, vegetables, and whole grains, which are natural sources of prebiotics, were negatively correlated with F. nucleatum abundance [89]. Dairy products, which often contain prebiotics such as GOS, were also linked to reduced levels of F. nucleatum. According to these results, prebiotics may indirectly affect F. nucleatum by providing an environment that favors beneficial microbes and makes opportunistic pathogens less likely to succeed [90].

Moreover, the production of SCFAs by prebiotic fermentation, particularly butyrate, has been identified as a critical mechanism of prebiotic suppression. A meta-analysis showed that SCFAs, particularly butyrate, inhibit F. nucleatum growth by acidifying the gut environment. Aside from its anti-inflammatory and anti-carcinogenic properties, butyrate is also believed to provide additional protection against colon cancer [91]. The direct evidence linking prebiotics to a reduction in F. nucleatum levels remains limited, despite these promising results. A number of studies point to changes in gut microbial diversity and SCFAs production as the cause of the suppression of F. nucleatum, inferring that these shifts are responsible for it [92]. The modulation of gut microbiota by prebiotics consistently leads to an increase in Bifidobacterium and Lactobacillus, both associated with a decrease in pathogenic bacteria. However, the specific interactions between these changes and F. nucleatum remain underexplored [93]. Furthermore, A large-scale clinical trial evaluating the effects of prebiotics, such as inulin, FOS, and XOS on F. nucleatum should be prioritized for future research. Studies on the mechanisms involved in prebiotic interactions with gut microbiota and F. nucleatum are also necessary. These studies must focus primarily on SCFAs-mediated pathways and microbiota-host interactions. These could lead to personalized nutrition recommendations targeting F. nucleatum to prevent and manage CRC [94].

Dietary modifications

People who consume a variety of foods exhibit significant differences in their metabolisms and gut microbiota, suggesting that the gut microbiota might have a significant impact on the correlation between diet and the risk of CRC [95]. It has been shown that when an individual changes his dietary pattern from a traditional African diet (high in plant polysaccharides, fiber, low in fat and processed meat) to a Western diet (high in fat, processed meat, and sugar), a rapid change in microbial abundance and composition is observed. The gut of rural Africans is dominated by species of the Prevotella family, which are responsible for starch, xylan, and hemicellulose degradation. As a result, the Bacteroides genus is more prevalent in the microbiota of Americans, and it contains more detrimental Proteobacteria, including Escherichia and Acinetobacter [96]. In African countries, CRC incidence is lower than in Western countries due to these differences in microbial structure. Similar variations can be observed in the profile of feces metabolites, with native Africans exhibiting higher amounts of SCFAs and African Americans showing more significant amounts of secondary bile acids. According to the results of an intervention trial, African Americans switched to a diet that was high in fiber and low in fat for two weeks, resulting in increased SCFAs production, reduced secondary bile acid synthesis, and decreased markers of inflammation and cancer cell growth of the colonic mucosa [97]. Research suggests that a Western diet weakens the colonic mucus layer and may promote cancer growth by interacting with gut bacteria. As a barrier of defense, this mucus layer separates billions of gut bacteria from the host. Western diets result in less mucus production, making the colonic mucus barrier less effective. It is believed that these effects are related to changes in the microbial ecosystem and a decrease in Bifidobacterium and Bacteroidales, as SCFAs generators [98].

A cross-sectional study involving 212 healthy adults without a history of CRC or precancerous lesions found a significant inverse association between dairy product intake and the presence of F. nucleatum in fecal samples. However, dairy intake did not show any relationship with the presence of F. nucleatum in stools. This means that even if dairy may affect the composition of gut microbiota, it is not sufficient by itself to produce a change in the amounts of F. nucleatum present without other influences, such as dietary fiber intake [99]. Therefore, further studies would be required to determine how these associations occur and whether clinical effects can actually be observed with these dietary factors. While these findings emphasize the critical role of dietary habits to modify gut microbiota composition, they would also hold the promise of CRC prevention.

Diets with a large amount of fiber are indeed an essential component of gut microbiota modulation and have far-reaching and significant implications in the suppression of F. nucleatum in CRC. Dietary fiber, unable to be digested in the upper tract of the gastrointestinal system, serves as a substrate for its target beneficial commensal bacteria: Faecalibacterium prausnitzii, Bifidobacterium, and Roseburia. These fermenters convert fiber to SCFAs, such as butyrate, acetate, and propionate, which act against F. nucleatum [100]. Fiber-degrading bacteria compete with F. nucleatum for nutrients (carbohydrates) and physical niches in the colonic mucosa. F. prausnitzii, as a key butyrate producer, reduces the luminal pH by SCFAs secretion, rendering the environment unfavorable for F. nucleatum, which prefers neutral to alkaline conditions [101]. This pH change also inhibits F. nucleatum virulence factors such as the FadA adhesin, which is important for epithelial invasion. Butyrate is the main energy source for colonocytes, promoting epithelial integrity through the upregulation of tight junction proteins (e.g., occludin, ZO-1) and mucin production (e.g., MUC2). This also strengthens the mucosal barrier, limiting F. nucleatum translocation to submucosal tissues [69]. Butyrate is further helpful in imparting anti-inflammatory effects via inhibition of both NF-κB signaling and its associated pro-inflammatory cytokines (e.g., IL-6, TNF-α) that F. nucleatum exploits to promote tumorigenesis. It acts as a histone deacetylase (HDAC) inhibitor butyrate, which can reactivate some tumor suppressor genes like p21 and PTEN and shut down several oncogenic pathways like Wnt/β-catenin. It brings CRC cells under control in the sense that they now resist DNA damage or mutation introduced by F. nucleatum, including reactive ROS and MSI, which develop with time [102].

Plant-derived polyphenols, such as those from berries, green tea, pomegranate, etc., are supposed to possess antimicrobial effects directly inhibiting F. nucleatum in CRC. In this way, epigallocatechin-3-gallate (EGCG), present in green tea, inhibits F. nucleatum biofilm formation through its targeting of bacterial adhesins (radD) and the quorum-sensing pathways while resveratrol, which is obtained from grapes, inhibits F. nucleatum growth by interfering with the metabolism of folate as resveratrol is stated to have activity against this bacterium. Proanthocyanidins found in berries destabilize the membrane integrity of F. nucleatum to increase susceptibility to host defenses [103]. Further, these compounds change the gut environment by lowering pH or by metabolites such as urolithin that impede the colonization of F. nucleatum. Direct studies in humans are few, but in vitro studies and animal models showed the possible effect of polyphenols on regulating the virulence of F. nucleatum [104]. Compounds such as curcumin and quercetin inhibit activation of NF-κB, and therefore, this prevented the increase in pro-inflammatory cytokines such as IL-1β and TNF-α that F. nucleatum can use to produce tumorigenesis. Immunity against the effect of F. nucleatum suppression by DCs and cytotoxic T-cell activity is enhanced with resveratrol. Furthermore, these actions of polyphenols would scavenge most of the ROS produced out of infected epithelial cells by F. nucleatum, therefore reducing DNA damage and oxidative stress related to cancer progression [105]. All these mechanisms of anti-inflammation and anti-oxidation perfectly correlate with other strategies for preventing CRC.

Specific foods and nutrients shown to reduce F. nucleatum

Polyphenol rich foods

Polyphenols are bioactive plant compounds with antimicrobial, anti-inflammatory, and antioxidant properties. They disrupt the metabolic pathways of F. nucleatum, inhibit biofilm formation, and promote the growth of beneficial bacteria [106].

Green tea

Green tea is a rich source of catechins. In particular, epigallocatechin gallate (EGCG) has antimicrobial, anti-inflammatory, and antioxidant properties. By disrupting the bacterial membrane, EGCG affects bacterial growth and biofilm formation in F. nucleatum and improves the gut microbiome and promotes the spread of beneficial bacteria such as Bifidobacterium and Lactobacillus [107]. Previous study revealed that regular consumption of green tea catechins reduced the levels of F. nucleatum in the gut microbiota by 30% and also increased the production of SCFAs, which is also necessary for intestinal health [108]. In addition, the polyphenols in green tea help reduce inflammation throughout the body. This helps improve the integrity of the intestinal barrier. This makes green tea a functional food with the potential to improve gut health and inhibit pathogens [109].

Berries

In berries such as blueberries, blackberries, cranberries, and raspberry There is a lot of anthocyanin. It is a polyphenol with strong antimicrobial and anti-inflammatory properties. These anthocyanins inhibit F. nucleatum to prevent its attachment to epithelial cells. This is critical for colonization and biofilm formation [110]. These composts also adjust the microflora in the gut. By increasing the abundance of beneficial bacteria such as Akkermansia muciniphila and Roseburya, which produce SCFAs, a randomized clinical trial found that a diet rich in wild fruits reduced significantly F. nucleatum levels in patients, who have IBD and increases the diversity of microorganisms in the intestines [111].

Red wine and grapes

Red wine and grapes are excellent sources of resveratrol. This is a polyphenol known to have antimicrobial properties. anti-inflammatory and balances the intestinal microflora. Resveratrol inhibits F. nucleatum by interfering with virulence factors and reducing its ability to form biofilms. It also selectively increases the growth of beneficial intestinal bacteria such as Bifidobacterium and SCFAs-producing strains [112]. Resveratrol reduced F. nucleatum biofilm formation by 50% and inhibited the production of inflammatory markers such as IL-8 as part of a Mediterranean diet. Moderate amounts of red wine have been shown to promote microbial diversity and reduce inflammation. This makes wine a functional food that is effective in managing microbial imbalances in the gut [113].

Pomegranates

Pomegranates contain compounds called ellagitannins and punicalagin, which are metabolized by gut bacteria to urolithins. These composites have significant anti-inflammatory and antimicrobial effects. They improve intestinal barrier function and inhibit the spread of F. nucleatum. In a murine model of colon cancer, a study showed that pomegranate sucrose consumption reduced the abundance of F. nucleatum in the colon while increasing the abundance of SCFAs-producing bacteria [114]. Based on these findings, tanine has also been shown to be involved in inflammatory pathways, such as NF-κB signaling, which are activated by F. nucleatum. Romaine is an effective dietary intervention to prevent colon cancer and irritable bowel syndrome [115].

Bitter chocolate and cocoa

Both are rich in flavonoids such as epicatechin and catechin, which has prebiotic and antimicrobial properties. These flavones promote the growth of beneficial bacteria, Including Bifidobacterium and Lactobacillus at the same time as inhibiting pathogens such as F. nucleatum [116]. A study showed that cocoa flavonoids increased SCFAs production, which reduced intestinal permeability and inflammation. Flavonose also inhibits F. nucleatum biofilm formation, which further reduces colonization potential. Regular consumption of bitter chocolate is associated with better gut microbial diversity and reduce inflammation throughout the body. This makes chocolate a beneficial food for intestinal health [117].

Herbs and spices

Herbs and spices, such as alegrim, oregano, and thyme, are rich in polyphenols such as rosmarinic acid and carnosic acid. These composites have potent antimicrobial effects against F. nucleatum, which reduces its growth and biofilm formation discovered that alegrim and basil extracts inhibited F. nucleatum by 60% in test tubes [118]. While these extracts increase the abundance of beneficial SCFAs-producing bacteria. Additionally, the anti-inflammatory properties of these polyphenols help reduce inflammation in the intestines. This makes herbs and spices a valuable addition to a gut-friendly diet [119].

Orange and citrus fruits

Such as oranges, lemons, and grapefruit are rich in hesperidin and naringenin. This is a polyphenol known for its anti-inflammatory and antimicrobial properties. These compounds inhibit NF-κB activation and reduce bacterial synthesis, which is important for F. nucleatum colonization [120]. A study found that citrus polyphenols increased SCFAs production in mice with dysbiotic gut bacteria. They also found significant reduction in downregulation of inflammatory markers and improved intestinal barrier function. It is emphasized that citrus fruits are important nutritional tools for managing gut health [121].

Green leafy vegetables (broccoli and kale)

Broccoli and kale contain sulforaphane, a sulfur-containing compound with strong antimicrobial and anti-inflammatory properties. Sulforaphane inhibits F. nucleatum colonization by increasing SCFAs production and reducing its response. Dinkova-Kostova et al., found that sulforaphane protects intestinal epithelial cells from oxidative stress which supports the integrity of the intestinal barrier [122].

Garlic and allicin

The antimicrobial properties of garlic (Allium sativum) are widely recognized. This is mainly due to the bioactive sulfur compound, allicin, when garlic is crushed or minced. The enzymatic reaction between allicin and allinase creates allicin which exhibits broad-spectrum bactericidal activity. Allicin disrupts bacterial cell membranes and hinders energy production [123]. It inhibits important bacterial enzymes, especially those with thiol groups, and exhibited antimicrobial activity; as a result, bacterial viability and biofilm formation are reduced. This is important for F. nucleatum to colonize and persist [124]. In vitro studies revealed the effectiveness of allicin in reducing F. nucleatum growth. Research showed that allicin inhibits F. nucleatum at a concentration as low as 20 g/mL, demonstrating its potential as a natural antimicrobial agent [125]. In addition, a study found that dietary supplementation with garlic helped balance the microbiome and suppress inflammatory cytokines in mice, resulting in a lower incidence of F. nucleatum. Allicin can enhance antibacterial activity and inhibit biofilm formation when combined with conventional antibiotics or natural antibiotics such as green tea catechins [123]. Moreover, garlic has been clinically shown to mobilize the gut microbiome and improve oral health. There is evidence that garlic extract mouthwash can reduce F. nucleatum levels within subgingival plaque and improve periodontal parameters such as bleeding and pocket depth in a randomized trial. Also, diets rich in garlic have been associated with increased gut microbiota [126].

Curcumin

The main bioactive compounds in curcuma longa have received a lot of attention due to their antimicrobial, anti-inflammatory and antioxidants properties. Curcumin offers a versatile approach to combating F. nucleatum-induced disease by modulating inflammatory pathways, inhibits biofilm formation and the spread of bacteria [127]. Curcumin inhibits bacterial growth by interfering with essential metabolic pathways and biofilm architecture. F. nucleatum relies on biofilms for colonization and defence against the host’s immune response and effectively interferes with this process. Curcumin reduced biofilm formation and inhibited bacterial proliferation in vitro, as well. In addition, it also modulates inflammatory responses by inhibiting the NF-κB signaling pathway [128]. Curcumin improves the integrity of the intestinal barrier by increasing tight junction proteins. These findings indicate that curcumin not only reduces bacterial colonization, but it also increases the host’s resilience to infection-induced inflammation. Several animal studies have shown that curcumin inhibits inflammation caused by F. nucleatum [129]. In patients with colorectal liver metastases, curcumin has been shown to be a well-tolerated chemotherapeutic adjuvant to oxaliplatin chemotherapy. It inhibits cell cycle progression and mitigates inflammation caused by Tregs by regulating the gut microbiota [130].

Phage therapy

Bacteriophages (phages) targeting F. nucleatum have garnered attention for their potential in addressing infections associated with this bacterium, both in general and in the context of CRC. Phages specific to F. nucleatum offer a promising strategy for combating these effects due to their high specificity and ability to lyse the bacterium without disrupting beneficial microbiota [131]. In CRC, phages can selectively target F. nucleatum colonizing tumors, potentially reducing inflammation, tumor growth, and resistance to chemotherapies. Research is ongoing to characterize these phages, optimize their delivery to tumor sites, and evaluate their safety and efficacy in clinical settings, positioning them as a novel adjunctive therapy in managing CRC and associated infections [132] (Fig. 2).

Fig. 2.

Therapeutic strategies targeting F. nucleatum in CRC. Created in BioRender. Aliramezani, A. (2025) https://BioRender.com/ae1tvhi

FnpØ02 from Siphoviridae family, is a first-generation phage that infects F. nucleatum and provides a foundation to investigate the potential of phages to control related diseases in the future. The phage has a narrow range, as shown by the difference in sensitivities seen with F. nucleatum subsp nucleatum and F. nucleatum subsp vincentii compared to the phage’s sensitivity to F. nucleatum subsp polymorphum. According to this difference in efficiency, phage receptors are structurally different between subspecies, resulting in a lower affinity and a less efficient adsorption phase [133]. A study by Wang et al., identified five different isolates of bacteriophage that target F. nucleatum. They analyzed their morphological, biological, genomic, and functional characteristics of JD-Fnp1 ~ JD-Fnp5 by transmission electron microscopy to confirm that are all myoviruses. In terms of biological properties, including pH and heat stability, host range, and growth characteristics, JD-Fnp1 ~ JD-Fnp5 have different patterns. Among them, JD-Fnp4 shows the greatest potential for clinical applications against F. nucleatum [131]. Lam et al., reported a new F. nucleatum bacteriophage named ØTCUFN3 and investigated the in vivo and in vitro studies to identify how it could combat F. nucleatum-induced CRC growth. The application of ØTCUFN3 to F. nucleatum-induced CRC cells, p53+/+, and p53−/− isogenic HCT116 cells, proliferation and EMT marker expression were inhibited. ØTCUFN3 injections reduced the growth of mouse xenografts induced by F. nucleatum [134]. In addition, Zheng et al., discovered that oral or intravenous administration of irinotecan was effective in mice with orthotopic colorectal tumors or spontaneous colorectal tumors. In order to improve the effectiveness of first-line chemotherapy treatments for CRC, loaded dextran nanoparticles covalently linked to azide-modified phages that inhibit F. nucleatum growth have been developed. They also found that oral administration of phage-guided irinotecan-loaded nanoparticles did not alter haemocyte counts, immunoglobulin, histamine levels, or liver and renal function in piglets [135].

In order to remove the biofilm induced by F. nucleatum several phages were isolated and stated in the past. Phages targeting these biofilms can penetrate the protective matrix, disrupt bacterial communities, and enhance bacterial clearance, making them effective even against antibiotic-resistant strains. These phages offer a precision approach, sparing beneficial gut microbiota while reducing biofilm-associated pathogenicity [136]. Research is focused on characterizing phage-biofilm interactions, optimizing phage delivery to tumor sites, and integrating phage therapy with conventional CRC treatments, highlighting their potential as a novel strategy for combating biofilm-mediated complications in F. nucleatum-associated diseases [137]. ØFunu1, ØFunu2, FnpØ02, FnpØ13 were reported as a fast absorbed and with slow cell surface lysis function infecting F. nucleatum [131]. In another study conducted by Shen et al., the potential biomarkers for CRC have been identified from 317 metagenomic samples obtained from China, Austria, Japan, where five intestinal bacteriophages were identified as potential biomarkers. These included F. nucleatum, Peptacetobacter hiranonis, and Parvimonas micra phages. They aimed to provide a novel perspective for intestinal phagocytosis therapy of CRC by expanding the existing ØFunu1, ØFunu2 and ØFunu3 prophage biomarkers [19]. Using the FNU1 phage, Kabwe et al., assessed the ability of the phage to break down biofilms mass by about 70% of F. nucleatum and kill the bacteria within, thus offering another treatment option for this bacterium. Using FNU1, biofilms formed by F. nucleatum can be broken down and the bacterial cells lysed. As a result, this bacteriophage can be tested in a variety of complex oral biofilm assays and could potentially be tested in vivo, assessing its ability to treat periodontitis and CRC, if it is formulated in the appropriate dose form [138].

The development of phage therapy for treating F. nucleatum infections faces several technical and regulatory challenges. Technically, isolating and characterizing phages with high specificity and efficacy against F. nucleatum strains is complex due to the bacterium’s genetic diversity and biofilm-forming ability. Phages must demonstrate the capacity to penetrate biofilms and remain stable in the gastrointestinal environment, especially in CRC treatment [139]. Regulatory challenges include establishing standardized manufacturing processes, ensuring phage purity, and validating safety in humans, particularly to address concerns about horizontal gene transfer of resistance genes. Moreover, personalized phage cocktails tailored to individual infections complicate regulatory pathways, as each preparation may require separate approvals [140]. Overcoming these hurdles requires robust clinical trials, clear guidelines from regulatory bodies, and interdisciplinary collaboration to advance phage therapy into practical and safe clinical applications for F. nucleatum.

Immune modulation therapies

Immune checkpoint inhibitors and their role in CRC

Immune checkpoint inhibitors (ICIs) restore T-cell function by blocking inhibitory pathways, particularly CTLA-4 and PD-1/PD-L1, which suppress anti-tumor immune responses. CTLA-4 competes with CD28 for B7 ligands on antigen-presenting cells, dampening early T-cell activation. FDA-approved agents like ipilimumab (anti-CTLA-4) and pembrolizumab (anti-PD-1) enhance T-cell-mediated immunity and reduce regulatory T cell (Treg) suppression [141]. In CRC, PD-1 and PD-L1 inhibitors have shown survival benefits. A network meta-analysis of 12 randomized trials revealed that PD-L1 inhibitors improved overall survival, while PD-1 inhibitors prolonged progression-free survival. For example, the KEYNOTE-177 trial demonstrated superior outcomes with pembrolizumab in metastatic CRC. A combination of nivolumab (anti-PD-1) and ipilimumab achieved a 54.6% response rate in MSI-H CRC patients [142].

However, ICIs remain largely ineffective in microsatellite-stable (MSS) or mismatch repair-proficient (pMMR) CRC, which comprise ~ 95% of cases. These tumors exhibit poor T-cell infiltration and low neoantigen load. F. nucleatum has been implicated in suppressing T-cell responses and promoting Treg recruitment, further limiting ICI efficacy [143]. Paradoxically, recent studies suggest that F. nucleatum may sensitize MSS CRC to immunotherapy. Gao et al. reported that high F. nucleatum levels enhanced the therapeutic effect of PD-L1 blockade in mice with CRC, improving survival [144]. Similarly, Wang et al., found that fecal microbiota transplants (FMTs) from F. nucleatum-high MSS CRC patients conferred anti-PD-1 sensitivity to germ-free mice [145]. In both murine and humanized models, F. nucleatum administration potentiated anti-PD-1 efficacy, suggesting that its presence may serve as a predictive biomarker for immunotherapy response in MSS CRC [146]. Together, these findings highlight a dual role of F. nucleatum as both a tumor promoter and a potential enhancer of ICI response offering new insights for personalized immunotherapy in CRC.

Vaccine development

The main challenge in developing a vaccine against F. nucleatum lies in its complex interaction with the host immune system. and the ability to adapt to immune responses within the tumor microenvironment. Meanwhile, vaccine development criteria against F. nucleatum includes the role of the bacterium in CRC in various aspects, including adherence to epithelial cells, immune modulation and promoting tumor progression [147]. Research into vaccine development against F. nucleatum has identified several important virulence factors that may serve as vaccine targets. Among these proteins, FadA is one of the most promising proteins which plays a key role in the ability of the bacterium to adhere to and invade epithelial cells. It has been shown that FadA activates β-catenin synalation, which promotes the proliferation and survival of cancer cells. As a result, antibodies that detect FadA can prevent F. nucleatum from adhering to colonocytes, suppressing its protumorigenic effects [148]. Targeting FadA has shown potential in blocking F. nucleatum-induced signaling pathways, thereby reducing tumor progression. Vaccines targeting F. nucleatum offer a promising strategy for preventing its colonization and pathogenic effects in CRC [5]. Similarly, preclinical studies have demonstrated the efficacy of FomA-based vaccines in reducing F. nucleatum colonization and mitigating its pro-tumorigenic effects. For instance, mice vaccinated with FomA exhibited reduced bacterial load and lower levels of inflammation in colorectal tissues [149].

In addition to FadA, other surface proteins such as the outer membrane proteins of F. nucleatum (FnOmpA) and its nuclear acid binding protein (Fap2) has also been identified as a potential candidate for vaccine development. These proteins play important roles in immune modulation and in the interaction of bacteria with host cells. It has been shown that Fap2 interacts specifically with T-cell immunoglobulin and mucin domain (TIM-1), an immune checkpoint molecule. This contributes to suppression of the immune response within the tumor microenvironment [6]. Furthermore, vaccines targeting these proteins not only inhibit colonization by F. nucleatum, but may also modulate the immune system to enhance anti-cancer immunity. Tong et al., demonstrated that combination of tubeimuside I (TBI) and F. nucleatum specific DCs (NTB-F. nucleatum-DCs) improves the efficacy of a therapeutic colorectal cancer vaccine [150]. DNA vaccines are another promising strategy. By inhibiting tumor progression and development, the NTB-F. nucleatum-DCs had excellent antibacterial and antitumor effects on CRC mice. There has been extensive research on immunization strategies with vaccines against F. nucleatum, including protein-based vaccines, DNA vaccines, and live attenuated vaccines. This is because protein-based vaccines tend to be more easily accessible whereas recombinant proteins such as FadA and Fap2 are expressed without a transport system and are injected into the host to stimulate an immune response. As bacterial antigens are encoded directly on host cells, F. nucleatum can stimulate both humoral and cellular immunity [150].

Taken together, therapeutic vaccines can be combined with other treatments, such as ICIs, to boost tumor-specific immune responses. This prevents F. nucleatum from triggering an immune-suppressive microenvironment. The vaccine can work with ICI to restore anti-cancer immunity. This is especially true in non-CRC where MSS, where so-called ICIs are less effective.

Novel and emerging therapies

CRISPR and gene editing

Targeting F. nucleatum with CRISPR-based technologies offers a highly precise and innovative approach to combat infections and diseases associated with this bacterium, including CRC. CRISPR-Cas systems can be engineered to selectively target and cleave essential genes in F. nucleatum, disrupting its survival, virulence, and ability to form biofilms. This technology also allows for the specific targeting of F. nucleatum within complex microbial communities, minimizing collateral damage to beneficial microbiota [151]. Additionally, CRISPR can be harnessed to silence genes such as fadA, which plays a key role in the bacterium’s adhesion to colonocytes and tumorigenesis. Delivery systems, such as phage-based vectors, are being explored to ensure efficient and targeted CRISPR delivery to F. nucleatum [152]. While promising, challenges remain, including optimizing delivery mechanisms, ensuring safety, and addressing potential off-target effects, but CRISPR-based strategies hold significant potential for developing precision therapies against F. nucleatum [153].

Although the gene inactivation in F. nucleatum is time consuming due to the genetically intractable nature of this bacterium, Zhou et al., CRISPRi (CRISPR interference) system based on the inducible riboswitch. Using a continuously expressed single-guide RNA (sgRNA), this system uses the nuclease-inactive Cas9 protein from Streptococcus pyogenes. The dCas9-sgRNA inhibits the target gene transcription by unbeatable blocking RNA polymerase function. Several essential (bamA and ftsZ) and non-essential genes (ftsX, radD) were examined to recheck and reestablish function across various fusobacterial strains. As a result of bamA suppression, membrane integrity and bacterial separation are disrupted, stalling growth, while ftsZ targeting leads to elongated cells in broth with compromised growth on agar. On the other hand, manipulation of the non-essential ones alters the Fusobacterial cytokinesis and coaggregation through filamentous cell formation or reducing RadD protein levels. Also, this system targeted other genes (ftsZ, tnaA) in distinct Fusobacterial strains for in-depth genetic studies and unlocking targeted therapeutic strategies [154].

In addition, CRISPR could develop and implement for strain level detection of F. nucleatum in CRC specimens. It can be used to identify F. nucleatum strains in cryopreserved samples, compared with traditional AP-PCR, which is limited to isolates. With this method, the disadvantages of culturing are eliminated, including time loss, skill bias, and low detection limits, and data can be collected and analyzed quickly for high-throughput analysis without experiencing any of the disadvantages of culturing. By utilizing the new method, it will be possible to prevent recurrence of CRC after removal and suppress carcinogenesis from adenoma [151]. In another case, Alyami et al., provided some evidence regarding how polymorphonuclear neutrophils (PMNs) employ phagocytosis and neutrophil extracellular traps (NETs) to combat F. nucleatum through nucleotide oligomerization domain 1 (NOD1) and NOD2 receptors (NLRs). Knocking out NOD1/NOD2 HL-60 cells with CRISPR/Cas9 and inhibiting NOD signaling confirmed the role of NLRs in NETosis mediated by F. nucleatum [155]. Moreover, to discover how sialic acid–binding immunoglobulin-like lectins (siglecs) are involved in innate immune cell modulation during CRC, Lamprinaki et al., silenced these lectins via CRISPR-Cas9 in in human monocyte-derived dendritic cells and LPS O-antigen purified from F. nucleatum ssp. animalis. Siglec-7 plays a new role in modulating immune responses by F. nucleatum strains and their OMVs by recognizing LPS on bacterial cell surfaces [156]. As a result, a deeper understanding of how F. nucleatum promotes the progression of CRC by creating a pro-inflammatory environment and a molecular basis for developing new cancer therapeutic approaches that target the F. nucleatum-Siglec-7 interaction is further provided. In this way, the RadD from F. nucleatum subsp nucleatum inhibits NK cell-mediated killing of cancer cells, as demonstrated by Galaski et al. [157].

Small molecule inhibitors

On the other hand, development novel small inhibitory molecules by drug repositioning could be an effective strategy to treat CRC. A total of 2,272 off-patent drugs were screened for inhibitory activity against F. nucleatum. Among the hit compounds, nitisinone was identified as a promising lead compound. Optimisation of nitisinone led to the discovery of more potent derivatives, notably 19q and 22c, which proved potent anti-F. nucleatum activity with low cytotoxicity. The compound 19q demonstrated the most effective ability to attenuate MC-38 cells induced by F. nucleatum (MIC50 = 1 µg/mL). It is worth noting that the small molecule, 1,3-di-m-tolyl-urea (DMTU), inhibits polymicrobial biofilm communities and their virulence factors in the oral cavity without any toxic effects on human cells. By affecting biofilm matrix, DMTU also disrupts mature biofilms in a dose-dependent manner, offering promise as a prophylactic and therapeutic agent. Wistar rats infected with Streptococcus mutans showed immunomodulatory and anti-infective effects. Other urea derivatives, such as (S-3, 4-dicholorobenzene)-isothiourea hydrochloride, were shown to bind competitively to MreB, a cell wall protein that is widely present in Gram-negative bacteria. It alters the cell shape, affects adhesion, biofilm formation and motility of Pseudomonas aeruginosa as well [158]. Other compounds, such as Mitomycin C, Microcin E492, Rakicidin A, and Herboxidiene, have not been reported to directly inhibit F. nucleatum, but are included due to their significant in vitro and in vivo anticancer potential in colorectal adenocarcinoma models [159–162].

Using the F. nucleatum cytoplasmic membrane fused with antibiotic-loaded liposomes, Chen et al., designed F. nucleatum-mimicking nanovehicles (LipoFM). They found that these nanovehicles were selectively effective in eliminating tumor-resident F. nucleatum and significantly improved chemotherapy efficiency. LipoFM loaded with colistin can selectively eradicate intratumoral F. nucleatum, thus improving chemotherapy efficacy. Moreover, LipoFM loaded with doxycycline can disrupt other intratumoral microbiomes involved in cancer metastasis [163]. Also, a multifaceted supramolecular nanomedicine was fabricated by conjugating lauric acid (LA) with platinum (IV) oxaliplatin prodrug followed by the addition of cucurbit [7] uril (CB [7]) to achieve supramolecular assembly. As a result of LA’s ability to eliminate the F. nucleatum, oxaliplatin’s chemotherapeutic efficacy is enhanced. Moreover, CB [7] facilitates oxaliplatin-host complexation, enabling its activation specifically in tumors overexpressed with spermine. Likewise, CB [7] facilitates supramolecular assembly between PG-Pt-LA nanoparticle self-assembly units. It has been shown that PG-Pt-LA/CB [7], in co-localized HT29 and CT26luc mouse models, is a targeted and safe nanomedicine that can promote chemotherapeutic efficacy in treating drug-resistant CRC [164].

A gold nanocluster (AuNC) of ultra-small size demonstrated potent antibacterial properties against F. nucleatum by destroying bacterial membranes and generating reactive oxygen species. In vitro, AuNCs inhibited biofilm formation and destroyed biofilms due to their excellent penetration. AuNCs were shown to reduce biofilm accumulation and improve inflammation in a mouse model, demonstrating their antibiofilm efficacy. Additionally, AuNCs were able to partially restore oral and gut microbiota disruption caused by oral F. nucleatum colonization [165]. Furthermore, inhibitory Effect of KSL-W peptide-loaded poloxamer 407-based microemulsions on F. nucleatum biofilms was reported by Bernegossi et al., leading to a significant reduction in the formation of the biofilms and showing promising structural properties for drug delivery. It was found that poloxamer 407-based microemulsions containing KSL-W were more effective than those containing chlorhexidine after 4 h incubation [166]. Furthermore, a study found that pre-resection antibiotics targeting anaerobic bacteria significantly improved disease-free survival in patients with CRC. Their study demonstrated that silver-tinidazole liposomes (LipoAgTNZ) could eliminate tumor-associated bacteria without interfering with the gut microbiome. A LipoAgTNZ treatment enabled more than 70% long-term survival in two F. nucleatum-infected mouse models of CRC colonized by tumor-promoting bacteria (F. nucleatum) or probiotics (E. coli Nissle). Natural products may be effective against the bacterium if certain properties are present in them [145].

F. nucleatum has been shown to be able to colonize colorectal cancers due to its affinity for the membrane protein Fap2 expressed on colorectal tumor cells. This has been demonstrated by clinical samples and animal tumor models. An immune-suppressive tumor microenvironment induced by F. nucleatum colonization can reduce the effectiveness of immune checkpoint blockade (ICB) treatment [167]. Using the cytoplasmic membrane along with liposomes containing colistin, F. nucleatum-mimetic nanomedicines are designed to kill tumors while preserving gut microbes. The therapeutic effects of ICB therapy on F. nucleatum-colonized tumors are successfully restored even in models of chemically induced spontaneous colorectal cancer, MC-38 tumors, and CT-26 tumors [168]. It has been hypothesized that it is possible to deliver antitumor drugs through antibacterial polymeric carriers to tumors that contain intratumor microbiota using a combined anticancer and antibacterial therapeutic strategy [169]. Tellurium-containing polycarbonate complexed with cisplatin was used as a drug carrier for oral tellurium (PTE@CDDP) by Hu et al., It has been shown in both in vitro and in vivo studies that PTE@CDDP can inhibit intratumor F. nucleatum and reduce inflammation in the tumor site. According to the study, CDDP-loaded tellurium-containing nanoparticles could significantly improve the treatment of F. nucleatum-promoted CRC through intratumor microbiota modulation and chemotherapy [170].

A CRC treatment’s efficacy is enhanced if antibiotics are used to target intratumoral bacteria while not affecting the gut microbiota. Several animal infectious disease models have shown activity after intravenous administration of nano-mupirocin, and no cross-resistance with other commonly used antibiotics has been detected [171, 172]. Cern et al., demonstrate that Nano-mupirocin targets tumor-residing F. nucleatum without affecting the gut microbiome immediately. Since bacteria are rapidly becoming resistant to existing antibiotics, as well as biofilms forming, antimicrobial peptides (AMPs) are becoming next-generation alternative antibacterial agents [171]. An amphiphilic polymeric nanodrug integrated with superparamagnetic iron oxide nanoparticles for the treatment of colorectal cancer that acts synergistically on both bacteria and tumors also was explained [173]. In a recent study by Li et al., developed a nanodrug (OPPL) that combines oleic acid-modified superparamagnetic iron oxide nanoparticles (O-SPIONs) with an amphiphilic polymer (PPL) to enhance the treatment of CRC with platinum prodrugs and antimicrobial lauric acid (LA). As a result of its peroxidase-like activity, OPPL can enhance antibacterial and biofilm disruption activities against F. nucleatum and LA simultaneously. An in vivo study showed that OPPL nanodrugs enhanced tumor accumulation, enabled magnetic resonance imaging, suppressed tumor growth, and inhibited F. nucleatum protein production in tumors [173]. Furthermore, broad-spectrum antimicrobial agents, though effective in treating F. nucleatum infections, may worsen dysbiosis. Rutherford et al., investigated the potential of the Fusobacterial enoyl-ACP reductase II (ENR II) isoenzyme, FnFabK (C4N14_04250), as a promising narrow-spectrum drug target. ENRs are essential enzymes in the bacterial fatty acid synthesis pathway, responsible for catalyzing the rate-limiting reduction step. This step is critical for bacterial survival and proliferation, making ENRs attractive targets for antimicrobial development [174]. By focusing on the FnFabK isoenzyme unique to F. nucleatum, the study highlights the possibility of designing targeted therapies that disrupt the pathogen’s fatty acid synthesis without significantly affecting the host or beneficial microbiota, thereby minimizing collateral damage and reducing the risk of dysbiosis.

Using rational design, Liu et al. conjugated 23R to a statherin-derived peptide (SDP); this conjugate binds to FomA, a major porin protein of F. nucleatum. They found that 0.1 nM SDP-23R cleared F. nucleatum ATCC 25,586 to 99% without significantly altering resident microbiota in a human gut microbiota model. AMPs that are bound to peptides show increased killing efficacy and specificity without altering resident microbiota in a study of target pathogens [175]. Another antimicrobial peptide developed by Jia et al., named Jelleine-I derivative Br-J-I demonstrated the highest anti- F. nucleatum activity, suggesting that Br-J-I disrupts F. nucleatum membranes by targeting membrane-associated FadA. In addition, F. nucleatum induced the growth of CRC cells-derived xenograft tumors, whereas Br-J-I suppressed the load of it in the colon and the inflammation caused by the bacterium [176].

Integrative and holistic approaches

Lifestyle changes, including diet, exercise, smoking cessation, alcohol moderation and pollutants management, play a crucial role in supporting the treatment of F. nucleatum-related CRC. These changes can improve gut health, modulate the microbiome, reduce inflammation, and enhance immune responses, all of which are essential in preventing and managing this disease. However, it is important to note that while lifestyle changes can be beneficial, they should complement, not replace conventional medical treatments such as chemotherapy, radiation, or targeted therapies for CRC [177].

Physical activity

Physical activity has emerged as a critical component of cancer prevention and control. The mortality rate among survivors of colorectal cancer may be reduced by up to 38% if physical activity levels are increased throughout the cancer care continuum [178]. The study by Himbert et al., found that CRC patients who were physically active, particularly those with normal weight or those who were overweight/obese but active, had greater gut microbiome diversity compared to inactive patients. Inactive patients showed lower diversity and altered bacterial abundances, suggesting that physical activity may help counteract obesity-related dysbiosis and improve gut health [179]. Similarly, Nierengarten et al., study highlighted that active CRC patients, regardless of BMI, had healthier gut microbiomes with enriched bacterial abundances. The research supports that adhering to physical activity guidelines (150 min per week) can benefit gut health and reduce obesity-induced dysbiosis [180].

Another study conducted by Boytar et al., examined the relationship between exercise, gut microbiota changes, and CRC. Exercise promotes a healthier gut microbiota, lowering the risk of CRC by promoting a healthier microbial profile. The research emphasized that exercise enhanced microbial diversity and increased beneficial SCFAs production, such as butyrate, which was associated with reduced inflammation and improved gut barrier integrity as key factors in CRC prevention. Despite promising evidence, the precise mechanisms linking exercise-induced microbiota changes to cancer protection remained underexplored and warranted further investigation [181]. Several animal studies have indicated that exercise alters gut microbiota composition and increases SCFAs synthesis. Physical activity increased the ratio of Bacteroidetes to Firmicutes, which fell in mice with obesity, increased proportionally with activity, and restored bacterial diversity in obese rats. An increased level of physical activity contributes to a lower risk of CRC by improving insulin sensitivity, decreasing circulating insulin, and reducing inflammation [182]. This condition is known to promote cancer cell proliferation, and regular exercise suppresses inflammatory pathways. Regular exercise improves gut motility and transit time, thereby reducing the time potential carcinogens come into contact with the lining of the gut. Exercise can influence the secretion of certain hormones (e.g., estrogen) that can influence the development of CRC, especially in postmenopausal or obese individuals [183].

Obesity and weight gain

The risk of CRC is consistently increased with an increase in body weight during adulthood, according to several epidemiological studies. Each 5-kg/m2 increase in body mass index (BMI) increases the risk of CRC by 5% [184]. It has been shown that obesity is associated with numerous physiological and immunological parameters, including insulin growth factor 1 signaling, sex hormones, adipokines, and systemic inflammation. It has been proposed that the gut microbiota controls the host’s metabolism and is associated with metabolic changes associated with obesity, including inflammation and insulin resistance. Both the gut microbiome and obesity are connected [185]. People who are obese tend to have an imbalanced gut microbiota, with a decrease in the Bacteroidetes group and an increase in the Firmicutes. There has been an increase in Enterobacter species and Clostridia, including Clostridium leptum, as well as Firmicutes. There are upregulations in Enterobacteriaceae species and Bacteroidales genera, including Bacteroides spp., Lactobacillus spp., Enterococcus spp., and Bifidobacterium spp [186]. This relationship is not straightforward, however, as the changes in gut microbiota are not only a consequence of obesity. Despite consuming less than normal amounts of food, mice transplanted with the gut microbiota from obese mice became overweight after receiving the transplant. According to this study, gut microbiota may contribute to obesity. The use of antibiotics in early childhood can disrupt the gut microbiota and increase the risk of obesity and other health issues, including CRC. It is, however, important to clarify whether these two conditions are related [187].

Obesity may change the gut microbiota, altering proinflammatory chemicals (LPS) and metabolites generated by microorganisms, which could lead to cancer. In addition to affecting gut barrier function, these modifications can increase permeability, which could accelerate cancer development. Studies in animal models indicate that intestinal barrier impairment, resulting in increased mucosal permeability, contributes significantly to bacterial translocation. As a result of (i) an increased permeability of the intestinal mucosal barrier, gut bacteria can propagate, (ii) a deficient immune system in the host, and (iii) a disturbed gastrointestinal ecology. These three pathways might promote the spread of gut-derived bacteria systemically, leading to infections in various parts of the body. In animal models where the intestinal barrier is not physically disrupted, bacteria migrate across epithelial cells via an intracellular pathway across the epithelial cells. The bacteria then migrate to the mesenteric lymph nodes via lymph [188]. By signaling through TLR4 and MyD88 in the lamina propria, bacteria or their byproducts trigger immune responses in the body when they come into direct contact with it. As a result of this interaction, especially with LPS from gut bacteria, proinflammatory mediators are released, contributing to local inflammation. An inhibitor of the LPS-TLR4 signaling pathway, TAK-242, can be administered intraperitoneally to mitigate the effects of intestinal barrier disruption by dampening this inflammatory response [189].

By affecting the intestinal barrier function, obesity can cause inflammation throughout the body. People who are overweight tend to have higher blood levels of LPS and LPS-binding protein (LBP), which can cause metabolic endotoxemia which can lead to leakage of LPS. Losing weight can reduce these levels [190]. In Li et al., research, there is evidence of a connection between CRC, gut bacteria, and obesity that may be influenced by epigenetic changes [191]. According to the previous studies, a diet rich in fat altered the acetylation patterns in genes that control gene expression, possibly contributing to CRC. In animals fed the same diet but given bacteria from non-obese donors, the changes did not occur, leading researchers to conclude that gut bacteria were responsible for the changes [192]. A combination of a high-fat diet and fecal transplantation produced gene expression patterns identical to those of human CRC. These results imply that relationships between adiposity and the gut microbiome may impact the host’s epigenome, raising the risk of CRC. There is still a need for further research to determine the precise role of the gut microbiota in this process [193].

Smoking and alcohol consumption

Although the causes of smoking-associated changes in the composition of the gut microbiota remains to be elucidated, preliminary evidence suggests a collective role of host, microbial, and environmental changes, such as disruption of the gut and immune system, impaired clearance of pathogens, change in bacterial and fungi virulence, altered growth and exopolysaccharide structure of gut bacteria, and ingestion of cigarette-derived bacteria [194]. Wine, beer, and spirits have all been associated with an increased risk of CRC in a dose-dependent manner, regardless of the tumor’s subsite, sex, or geographic location. Several lines of evidence suggest that the gut microbiota plays a role in alcohol’s tumorigenic effects. According to studies conducted on humans and animals, chronic ethanol consumption causes dysbiosis, lowers Bacteroidetes and Firmicutes abundances, and enriches Proteobacteria and Actinobacteria. Structure changes in the gut microbiota have been linked to intestinal bacterial overgrowth and hyperpermeability, resulting in increased translocation of gram-negative microbial products from the intestinal lumen into the bloodstream [195].

In humans, abstinence from alcohol, however, has been shown to restore gut barrier integrity. Alcohol consumption, gut microbiota, and CRC metabolic risk are associated with endotoxemia, which contributes to systemic inflammation, insulin resistance, and type 2 diabetes. Chronic ethanol exposure also decreased the abundance of butyrate-producing taxa from the Clostridiales order, including F. prausnitzii, Coprococcus eutaactus, and Roseburia species [196]. Using comprehensive characterization of the gastrointestinal content, a study found that rats exposed to ethanol showed significant changes in several metabolic pathways critical to host physiology, including a significant decrease in SCFAs [197]. Finally, in addition to colorectal mucosal cells, several intestinal aerobes and facultative anaerobes contribute to the production of mutagen acetaldehyde from ethanol under aerobic conditions. There have been several bacteria identified as potential acetaldehyde accumulators, including Ruminococcus, Collinsella, Prevotella, and Coriobacterium, leading to the hypothesis that alterations to the gut microbiota of high alcohol consumers may lead to increased levels of acetaldehyde and ethanol oxidation in the colon and acetaldehyde in the colon above the minimum concentration that initiates carcinogenesis [198].

Pollution and toxins

Oxidative stress, chronic inflammation, and disruption of the gut microbiome, as well as pollution and environmental toxins, including air pollutants (PM2.5, PAHs), heavy metals (arsenic, cadmium), pesticides (glyphosate), and industrial chemicals (BPA, PCBs), increase CRC risk [199]. A study investigates the long-term effects of cadmium (Cd) exposure on CRC metastasis found that chronic, low-dose Cd exposure enhanced the invasion and metastasis of CRC cells without significantly affecting cell growth. Cd exposure led to the down-regulation of cell junction-related genes and the up-regulation of mobility-promoting molecules. This study identified that Cd activates EGFR signaling in a non-canonical way, inducing sustained activation of EGFR and triggering the Akt/mTOR pathway, which boosts CRC metastasis. This research revealed the unique EGFR signaling dynamics induced by Cd and highlights its role in promoting metastasis [200].

Kasmi et al., examined the potential carcinogenic effects of arsenic (As) in digestive cancers. It explores the association between arsenic exposure and various digestive cancers, including esophageal, gastric, colorectal, liver, pancreatic, and biliary cancers. The review analyzes 35 studies, including ecological, case-control, and cohort studies, and finds that a substantial number of studies suggest a potential link between arsenic exposure and digestive cancers, particularly in hepatopancreatic biliary (HPB) malignancies [201]. Other study explored the connection between toxic metal bioaccumulation and CRC, focusing on metals like lead (Pb), chromium (Cr), Cd, aluminum (Al), copper (Cu), mercury (Hg), and arsenic (As). These metals are often found in the environment due to industrial activities and pollution and, in time, build up in the human body, facilitating the occurrence as well as the further progress of CRC. Repeatedly tested metals were able to induce oxidative stress and DNA damage and disrupt essential cellular processes that can lead to cancer [202].

The accumulation of these metals in the human body over time, often found in the public environment due to industrial activities and pollution, contributes to the development and progression of CRC. The metals were known to induce oxidative stress and DNA damage, as well as disrupt essential cellular processes that may lead to cancer [202]. The study highlighted the role of Pb in promoting CRC through oxidative stress and inflammation. Cr, particularly in its hexavalent form, was linked to CRC development due to its cytotoxic and genotoxic effects. Cd’s role was complex, as both low and high doses affected colon cells differently, lower doses might have stimulated proliferation, while higher doses induced toxicity and apoptosis. The study also focused on the effects of other metals, including Cu, Hg, and As, on CRC risk, with Cu playing a role in cell proliferation, and Hg and As associated with a higher CRC risk due to their cytotoxicity [203] (Fig. 2).

Preventive strategies

Preventive approaches against F. nucleatum in CRC focus heavily on modulating the gut microbiome to either suppress its colonization or mitigate its pro-tumorigenic effects. Dietary interventions rich in fiber, polyphenols, and omega-3 fatty acids can support the growth of beneficial bacteria and reducing F. nucleatum abundance [204]. Prebiotics such as inulin and resistant starch promote butyrate-producing bacteria, which strengthen the epithelial barrier and exert anti-inflammatory effects. Probiotic formulations containing Lactobacillus and Bifidobacterium species may competitively inhibit F. nucleatum adhesion and biofilm formation. Antibiotic strategies though not preferred for long-term prevention have shown temporary efficacy in reducing F. nucleatum load in preclinical models, although concerns over resistance and collateral damage to commensals limit their routine use. Emerging technologies such as bacteriophage therapy have demonstrated specificity in lysing F. nucleatum, but their clinical translation will require rigorous safety and efficacy trials to prevent horizontal gene transfer and resistance development [137]. On a molecular level, inhibiting F. nucleatum’s virulence factors offers a precise preventive strategy. For example, small molecule inhibitors or monoclonal antibodies targeting the FadA adhesin could prevent epithelial binding and β-catenin activation. Disrupting signaling pathways activated by F. nucleatum such as TLR4/NF-κB or IL-6/STAT3 may attenuate inflammation and downstream tumor-promoting effects. Another promising direction includes the use of synthetic AMPs and nanocarriers to selectively target F. nucleatum biofilms while sparing beneficial microbes [205]. Furthermore, screening individuals for high F. nucleatum loads via fecal DNA or metagenomics could enable risk stratification and early intervention [206]. Immunization strategies, although still experimental, aim to prime the host immune system against F. nucleatum antigens, potentially reducing colonization and persistence. Together, these strategies support a multi-tiered approach to CRC prevention, integrating diet, microbiome modulation, precision therapeutics, and biomarker-based screening.

Bridging the translational gap from concept to clinic

Despite growing interest in targeting F. nucleatum in CRC, a significant gap persists between theoretical frameworks, preclinical findings, and clinical applications. Addressing these discontinuities is essential for advancing microbiota-informed cancer therapies.

First, theoretical models often operate under idealized assumptions, lacking ecological realism. They typically fail to incorporate the full complexity of host-microbiota interactions, including dynamic cross-talk between microbial communities and the immune system. This limits their predictive power when translated into in vivo or clinical settings.

Second, while preclinical models such as murine systems and simplified in vitro biofilms have yielded valuable mechanistic insights, they do not fully capture the heterogeneity of the human tumor microenvironment. In particular, inter-individual variability in microbiota composition, immune context, and tumor biology cannot be recapitulated entirely in these models. Additionally, many studies do not reflect polymicrobial biofilms or mucosal conditions observed in human CRC patients.

Third, clinical translation faces further challenges. Therapies such as phage therapy and AMPs raise biosafety, delivery, and specificity concerns. Moreover, a lack of validated biomarkers for stratifying patients based on F. nucleatum burden or virulence profiles limits the development of precision-targeted interventions. The variability in patient microbiomes adds another layer of complexity, potentially affecting treatment efficacy and reproducibility across cohorts.

Collectively, these gaps underscore the need for integrated translational pipelines that align mechanistic insights with real-world biological and clinical contexts. Advances in organoid technology, personalized microbiome profiling, and systems-level analyses will be pivotal in bridging these domains and achieving therapeutic relevance.

Conclusions and future directions

Although there have been notable advances in understanding the interaction between F. nucleatum and the host in CRC, there are still critical gaps in our understanding of the process. The exact molecular mechanisms by which F. nucleatum promotes tumor initiation and progression remain to be fully elucidated, especially the role in early-stage carcinogenesis that it plays. It is also unclear to what extent F. nucleatum is interacting with other members of the gut microbiome as well as how these interactions affect CRC progression once it is incorporated into the gut microbiome. F. nucleatum has been known to modulate host immunity in a number of ways, but the specific mechanisms by which it induces immunosuppression and influences the responses to immunotherapy require further investigation in order to determine how it operates. Furthermore, it is unclear which factors, such as genetic predisposition, dietary habits, and the composition of one’s microbiome, are associated with individual susceptibility to F. nucleatum-associated CRC. In addition to this question, it has not yet been determined whether it is a primary driver of tumorigenesis or an opportunistic colonizer that exacerbates cancers. The understanding of these gaps is essential in order for us to develop novel therapies for CRC and improve the outcomes of the treatment.

There is a critical need for more clinical trials and longitudinal studies to better understand the role of F. nucleatum in the development of CRC, to develop effective therapeutic interventions. It has been demonstrated in preclinical studies that F. nucleatum participates in the progression of CRC, but large-scale clinical trials are needed to validate these findings in diverse populations of patients with CRC. A longitudinal study that tracks the levels of this bacterium in CRC patients over a long period of time could be useful in understanding its role in tumor initiation, progression, and response to chemotherapy. Furthermore, well-designed clinical trials are needed to determine whether antibiotics, probiotics, phage therapy, and immunomodulatory approaches can reduce the burden of F. nucleatum and improve the outcome for patients. There is a potential for enhancing screening strategies and detecting early CRC by studying F. nucleatum as a potential biomarker through longitudinal cohort studies that could provide information about early detection and prognosis. It is key to understand how F. nucleatum interacts with diet, genetics, and the broader gut microbiome in clinical settings in order to provide valuable insights into how personalized treatment approaches can be created. The ability to translate microbiome-based findings into meaningful therapeutic and diagnostic advancements for CRC will be enhanced by addressing these research gaps through robust clinical and longitudinal studies.

It is imperative to use a multifaceted approach to effectively combat F. nucleatum in CRC, since no single strategy can address the complex role that this bacterium plays in the progress of the disease. A combination of antibiotics, probiotics, bacteriophage therapy, and immune-based interventions is necessary due to F. nucleatum’s ability to modulate the immune system, promote inflammation, and influence chemoresistance. In addition to antibiotics being able to aid in reducing F. nucleatum colonization, their potential to disrupt the gut microbiome also underscores the need for adjunct therapies, such as probiotics and dietary changes, to help restore the gut microbial balance. There is an opportunity to selectively eliminate F. nucleatum using bacteriophage therapy or AMPs without harming beneficial bacteria through these targeted approaches. As a result, immunotherapy and microbiome-based strategies are also promising approaches to counteracting the immunosuppression caused by F. nucleatum and enhancing the anti-tumor immune response. Future therapeutic strategies should prioritize combination therapies, cycling regimens, and the development of personalized microbiota-targeting approaches guided by resistance surveillance and genomic profiling. As well as this, individualized treatment plans incorporating genetic and dietary profiles, as well as microbiome profiles, may be able to optimize therapeutic outcomes. It is possible to develop a comprehensive and sustainable approach to mitigating the impact of F. nucleatum on the progression of CRC, the response to treatment, and the prognosis of patients if researchers and clinicians integrate multiple strategies. This combined approach will require further clinical research in order to refine it, and then translate it into a patient-specific intervention that is effective and safe.

Author contributions

ASK, BY, AR: Writing, review and editing. AR, AA: Writing original draft, review, editing and supervision: All authors have read and agreed to the published version of the manuscript.

Funding

Not applicable.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Not applicable.

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Not applicable.

Competing interests

The authors declare no competing interests.