Lactic acid bacteria in Asian fermented foods and their beneficial roles in human health

Abstract

Fermented foods have been a staple in human diets for thousands of years, garnering attention for their health and medicinal benefits. Rich in lactic acid bacteria (LAB) with probiotic properties, these foods play a crucial role in positively impacting the host's gut microbiome composition and overall health. With a long history of safe consumption, fermented foods effectively deliver LAB to humans. Intake of LAB from fermented foods offers three main benefits: (1) enhancing digestive function and managing chronic gastrointestinal conditions, (2) modulating the immune system and offering anti-inflammatory effects to prevent immune-related diseases, and (3) synthesizing vitamins and various bioactive compounds to improve human health. In this review, we highlighted the diverse LAB present in Asian fermented foods and emphasized LAB-rich fermented foods as a natural and effective solution for health enhancement and disease prevention.

Introduction

Fermented foods have long been a cornerstone of human diets, integral to cultures worldwide from the earliest developments of civilization to the present day. This widespread and historical reliance on fermentation is primarily due to its role as a food processing technology aimed at preservation. More than just extending shelf life, the fermentation process imbues foods with desirable functional properties, including probiotic, antimicrobial, and antioxidant characteristics (Tamang et al., 2016). These features are not merely incidental but play a crucial role in the health benefits associated with fermented foods. Particularly noteworthy are the probiotic properties attributed to the presence of lactic acid bacteria (LAB) within these foods, which are believed to exert a positive influence on the host's microbiome, thereby significantly contributing to improving the human's health (Kwofie et al., 2020).

To be considered promising, LAB strains found in fermented foods must exhibit. They must exhibit certain key characteristics, such as the ability to survive in the intestinal environment and be safe for human consumption (Sanders et al., 2010). In South Korea, the evaluation of probiotic safety is conducted rigorously, following the Probiotic Guidelines issued by the Korean Ministry of Food and Drug Safety (MFDS) in 2021. Specific strains, including 19 species such as Lactobacillus acidophilus, Lactobacillus gasseri, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, Lacticaseibacillus casei, Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus, Limosilactobacillus fermentum, Limosilactobacillus reuteri, Lactiplantibacillus plantarum, Ligilactobacillus salivarius, Lactococcus lactis, Enterococcus faecium, Enterococcus faecalis, Streptococcus thermophilus, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium longum, and Bifidobacterium animalis subsp. lactis, have been approved for human consumption by the MFDS, demonstrating their recognized safety and efficacy (Jeon et al., 2022). However, for non-notified species such as those in the Bacillus and Weissella genera, additional safety assessments are required, despite any dietary experience with these strains. This ensures they meet the necessary safety standards for probiotic use in humans. Fermented foods, consumed for thousands of years, provide a rich dietary experience with LAB. As a result, traditional fermented foods fundamentally act as delivery vehicles for LAB, ensuring their safety and effective delivery to the host’s gastrointestinal tract (Kariyawasam et al., 2021).

These LAB derived from such fermented foods exert a positive impact on digestive and overall gastrointestinal health (Mukherjee et al., 2023). Furthermore, the immune-modulating and anti-inflammatory properties of probiotics present in fermented foods contribute to strengthening the immune system and alleviating inflammation (Wastyk et al., 2021). Additionally, LAB obtained from fermented foods play a crucial role in synthesizing essential vitamins and bioactive compounds, enhancing the nutritional value of these foods and potentially offering therapeutic benefits (Carvalho and Conte-Junior, 2024).

With all these aspects, this review aimed to describe fermented foods as potential sources for delivering LAB to the host, focusing on the functional properties of LAB derived from fermented foods and their positive impact on health.

Main text

Diversity of probiotic strains in Asian fermented foods

Fermentation is recognized as one of the oldest food preservation methods in the world, not only extending the shelf life of foods but also reducing or eliminating toxic compounds present in foods. The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines fermented foods as "foods made through desired microbial growth and enzymatic conversions of food components."(Marco et al., 2021). The fermentation process in foods necessitates microbial activity and progresses through the action of endogenous or exogenous enzymes derived from raw material sources (Sharma et al., 2020). While occasional processing errors during this process can lead to food spoilage and foodborne illnesses, posing a threat to the host, the knowledge passed down from ancestors combined with modern technology results in fermented foods that are advantageous for long-term preservation and offer positive nutritional benefits (Patel et al., 2023; Sultan and Mar-E-Um, 2014).

Fermented foods are rich in a variety of LAB, which are considered potential probiotics. Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer health benefits on the host (Hotel and Cordoba, 2001). Among the properties induced by microbes present in fermented foods, the probiotic attributes are significantly augmented by the production of vitamins, amino acids, enzymes, exopolysaccharides (EPS), short-chain fatty acids (SCFA), and bioactive peptides by LAB. These components contribute to the enhancement of the host's health, offering beneficial effects (Deveci et al., 2023; Patel et al., 2013).

Fermented foods can be broadly categorized into five groups: (1) Soy-derived fermented foods, (2) Vegetable-derived fermented foods, (3) Fish-derived fermented foods, (4) Fermented breads and porridges, and (5) Alcoholic beverages. Within these categories of fermented foods, a variety of lactic acid bacteria can be found (Rhee et al., 2011). Table 1 illustrates the LAB contained in traditional fermented foods from Asian countries, categorized by fermented food types. The majority of LAB found in Asian soy-derived fermented foods are of the Bacillus species (Table 1). For other fermented foods beyond soy-derived, Lactobacillus species were predominantly identified, followed by other bacteria such as Leuconostoc, Enterococcus, Pediococcus, Lactococcus, and Weissella (Table 1). In essence, fermented products act as carriers of probiotics, efficiently delivering these beneficial microbes to the host and providing beneficial effects (Ilango and Antony, 2021). The primary health benefits provided by LAB derived from fermented foods include gastrointestinal health, immune system improvement, and the amelioration of various diseases through bioactive compounds derived from LAB (Chugh and Kamal-Eldin, 2020; Garcia-Gonzalez et al., 2021; Mathur et al., 2020).

Table 1.

Probiotic strains found in Asian traditional fermented foods

Categories of fermented food products	Nation	Traditional fermented food	Main material(s)	Lactic acid bacteria present	References
Fermented soybean products	Korea	Cheonggukjang	Soybeans	Enterococcus faecium, Bacillus amyloliquefaciens, Bacillus subtilis	Kim et al. (2022), Lee et al. (2016), Park et al. (2020)
		Doenjang	Soybeans	Enterococcus lactis, Pediococcus acidilactici, Lactiplantibacillus plantarum, Enterococcus faecium, Enterococcus faecalis, Bacillus licheniformis, Bacillus subtilis	Kharnaior and Tamang (2023), Oh et al. (2018)
		Kanjang	Soybeans	Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus safensis	Hwang et al. (2020)
	China	Tofu	Soybeans	Lactiplantibacillus plantarum	Li et al. (2017)
	Japan	Natto	Soybeans	Bacillus subtilis, Bacillus aureus, Bacillus licheniformis	Ngampuak et al. (2023), Zhang et al. (2020)
Fermented fish products	Korea	Jeotgal	Fish	Lactiplantibacillus plantarum	Lee et al. (2006)
			Octopus	Pediococcus pentosaceus	Son et al. (2018)
			Squid	Lactiplantibacillus plantarum	Kim et al. (2023)
	Japan	Funa-Sushi	Fish	Lacticaseibacillus paracasei, Lactiplantibacillus plantarum, Levilactobacillus brevis	Komatsuzaki et al. (2005)
	India	Shidal	Fish	Lactiplantibacillus plantarum, Pediococcus acidilactici, Pediococcus pentosaceus, Pediococcus lilii, Enterococcus hirae, Enterococcus lactis, Enterococcus faecium, Enterococcus faecalis	Gupta et al. (2021)
Fermented vegetable products	Korea	Kimchi	Oriental cabbage	Leuconostoc mesenteroide, Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Latilactobacillus sakei, Levilactobacillus brevis, Lactococcus lactis, Latilactobacillus graminis, Leuconostoc lactis, Lacticaseibacillus casei	Baick and Kim (2015), Kim and Chun (2005), Ko et al. (2009), Lee et al. (2021), Lee et al. (2015), Sathiyaseelan et al. (2022)
			Ponytail radish	Leuconostoc paramesenteroides, Leuconostoc mesenteroides, Lactiplantibacillus plantarum	Ko et al. (2009)
			Radish	Leuconostoc lactis, Leuconostoc mesenteroides, Lacticaseibacillus casei, Loigolactobacillus coryniformis	Ko et al. (2009)
			Wakegi	Lactiplantibacillus plantarum, Latilactobacillus sakei	Ko et al. (2009)
			Mustard leaf	Bacillus inaquosorum, Levilactobacillus brevis	Sathiyaseelan et al. (2022)
		Jangajji	Burdock	Lactiplantibacillus paraplantarum	Son et al. (2018)
	China	Chinese pickled	Fermented vegetables	Lactiplantibacillus plantarum, Levilactobacillus brevis, Weissella viridescens	Liu et al. (2021a)
		Suan-tsai	Chinese cabbage	Lactiplantibacillus plantarum, Levilactobacillus brevis	Guo et al. (2015)
	Japan	Nozawana-Zuke	Mustard leaf	Levilactobacillus brevis, Lactobacillus coprophilus, Latilactobacillus curvatus, Lactobacillus delbrueckii, Limosilactobacillus fermentum, Lactiplantibacillus plantarum, Leuconostoc mesenteroides, Leuconostoc lactis	Kawahara and Otani (2006)
Fermented bread and porridges	Korea	Jeung-pyun	Rice flour	Levilactobacillus brevis, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides, Lactobacillus crustorum, Limosilactobacillus fermentum, Lactobacillus harbinensis, Leuconostoc citreum, Lactococcus lactis, Weissella confusa, Leuconostoc gasicomitatum, Leuconostoc gelidum, Limosilactobacillus reuteri, Latilactobacillus curvatus, Leuconostoc lactis	Lim et al. (2018)
	India	Idli	Flour	Lactiplantibacillus plantarum, Lactococcus lactis, Lactiplantibacillus pentosus, Limosilactobacillus fermentum	Iyer et al. (2013), Sircar and Mandal (2023)
	Philippines	Puto	Rice	Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides, Leuconostoc citreum, Leuconostoc fallax	Kelly et al. (1995)
Fermented alcoholic beverages	Korea	Makgeolli	Rice	Pediococcus acidilactici, Pediococcus pentosaceus, Latilactobacillus curvatus, Lactobacillus curstorum	Park et al. (2015)
	China	Koumiss	Mares' milk	Lactobacillus helveticus, Lactobacillus acidophilus, Lactiplantibacillus plantarum, Lacticaseibacillus casei	Guo et al. (2015)
	India	Bhaati jaanr	Rice	Lactiplantibacillus plantarum	Giri et al. (2018)

Additionally, recent studies have shown an increase in research focusing on the intake of fermented foods and the improvement of the gut microbiome (Stiemsma et al., 2020). Therefore, consuming LAB through fermented foods is beneficial for maintaining health against pathogenic bacteria in the gut microbiome, and maintaining a normal balance of the gut microbiome aids in improving digestive health and the immune system.

Effects of LAB derived from fermented foods on gut microbiome, digestive function and gastrointestinal well-being

While gut microbiome dysbiosis is implicated in the onset of various diseases in the host, diet plays a pivotal role in shaping the bacterial communities of the gut microbiome, with LAB found in fermented foods considered potential probiotics (Abdel Tawab et al., 2023). Examination of the microbiome of fermented foods has revealed that fermented vegetable products are predominantly governed by the genera Leuconostoc, Lactobacillus, and Weissella, while the microbiome of fermented soybean products consists of Bacillus, Enterococcus, Leuconostoc, and Lactobacillus (Jung et al., 2011; Lee et al., 2022; Mannaa et al., 2021a). These microbiomes of fermented foods often contribute to the improvement of the host's gastrointestinal microbiota (Jang et al., 2014; Mota de Carvalho et al., 2018; Taylor Bryn et al., 2020). Enhanced gut microbiota, as facilitated by the consumption of fermented foods, plays a crucial role in various aspects of host health, including the promotion of enzyme and vitamin synthesis, preservation of nutrients, facilitation of food digestion, maintenance of the immune system, and overall improvement of gastrointestinal health (Fig. 1)(Bell et al., 2018).

Fig. 1.

Effects of LAB derived from fermented foods on gastrointestinal health

The intake of probiotics through fermented foods has been shown to significantly improve the balance of gut permeability and barrier function (Hiippala et al., 2018). This contributes to enriching the gut microbiota and enhancing the integrity of the gut barrier, thus inhibiting the onset of pathogens. Additionally, it plays a crucial role in improving glucose metabolism (Cabello-Olmo et al., 2019; Kwon et al., 2010; Salehi et al., 2022). Specifically, it has been observed that the consumption of probiotics such as Lactiplantibacillus plantarum and Bifidobacterium lactis can lead to the upregulation of Glucose Transporter-4 (GLUT4), subsequently increasing insulin sensitivity, which is particularly advantageous in managing and potentially improving conditions such as Type 2 diabetes (Kim et al., 2014; Li et al., 2014; Yu et al., 2023). Notably, research has identified that strains within the Lactobacillus genus, derived from fermented foods, can alter the gut microbiota composition, offering improvements in Type 2 diabetes management (Li et al., 2014; Wang et al., 2017; Zhou et al., 2021). Furthermore, LAB found in fermented foods increase the digestibility of certain dietary nutrients, thereby improving overall digestive efficiency (Parvez et al., 2006a). Among these, the production of β-galactosidase by LAB plays a crucial role in digesting lactose into monosaccharides, alleviating symptoms of lactose intolerance (Ibrahim et al., 2021). It was supported by studies that have highlighted the efficacy of specific LAB strains, such as Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, commonly used as starters in fermented dairy products, in providing relief from lactose intolerance (Jan et al., 2022; Kok and Hutkins, 2018; Rul et al., 2011; Yamamoto et al., 2021). Collectively, the probiotics in fermented foods improve digestive health by upregulating GLUT4 for better insulin sensitivity and controlling Type 2 diabetes, while also aiding lactose digestion and reducing intolerance through β-galactosidase production (Fig. 1).

Inflammatory Bowel Disease (IBD) and Irritable Bowel Syndrome (IBS) are quintessential gastrointestinal disorders characterized primarily by an imbalance in the gut microbiota, where a disproportion between beneficial and harmful bacteria leads to the compromise of the intestinal microbial barrier (Chelakkot et al., 2018; Qiu et al., 2022). IBD is a chronic inflammatory condition that encompasses diseases such as Ulcerative Colitis (UC) and Crohn's Disease (CD), while IBS is a functional gastrointestinal disorder marked by pain, bloating, and changes in bowel habits without distinct organic anomalies (Carco et al., 2020; Roda et al., 2020). The dysbiosis in the gut microbiota that triggers intestinal inflammation in both IBD and IBS suggests that manipulating the gut microbiota through probiotics could be an ideal treatment approach, especially considering the relationship between changes in the gut microbiota and intestinal inflammation (Lee and Bak, 2011). Numerous reports have highlighted the efficacy of probiotics in treating and preventing these gastrointestinal diseases through the improvement of the gut microbiota in mouse models (Duranti et al., 2016; Gaudier et al., 2005; Santos Rocha et al., 2012). Furthermore, the impact of dietary intake on the gut microbial community has been reported to control the progression of IBD and IBS (Fig. 1) (van Lanen et al., 2021; Zeng et al., 2021). These findings indicate the potential use of fermented foods, rich in LAB, as therapeutic agents for the improvement of gastrointestinal disorders. Indeed, research has shown symptom alleviation through the consumption of fermented foods, where LAB from these foods ferment polysaccharides in the diet, modulating the gut microbiota and altering its distribution (Liu et al., 2021b; Nielsen et al., 2018). Notably, Lactobacillus strains stimulate T regulatory (Treg) cells, producing anti-inflammatory agents, thereby offering beneficial effects against gastrointestinal diseases (Liu et al., 2010; Tanaka et al., 2020; Wasilewska et al., 2019).

These findings underscore the significant role of probiotics derived from fermented foods in enhancing digestive function through the improvement of the gut microbiota and metabolic regulation, thereby playing a crucial role in managing digestive disorders such as Type 2 diabetes and lactose intolerance. Additionally, they highlight the considerable potential in managing gastrointestinal diseases, presenting a promising approach to controlling the progression of IBD and IBS. The consumption of LAB from fermented foods suggests an effective strategy for managing gastrointestinal health (Fig. 1).

Effects of LAB derived from fermented foods on immune modulation and anti-inflammatory properties

Probiotics are known to positively influence the composition of gut microorganism and interact with immune cells to enhance immune function (Mazziotta et al., 2023; Zhou et al., 2020). Fermented foods serve as a distinctive reservoir for beneficial probiotics, notably LAB, contributing significantly to nutritional enhancement and well-being (Castellone et al., 2021; Salminen et al., 2004). These microbiological agents play a pivotal role in the metabolic fermentation process, leading to the production of bioactive compounds. Research efforts are intensively focused on elucidating the roles of fermented foods in augmenting antioxidative activities, enhancing digestive functions, and bolstering the efficacy of the immune system (Yan and Polk, 2011).

Probiotics play a pivotal role in orchestrating the body's immune responses, both innate and adaptive, by influencing the activity of critical immune cells such as dendritic cells, macrophages, and T and B lymphocytes (Fig. 2) (Roessler et al., 2008). This regulatory effect is partly achieved through the stimulation of toll-like receptors (TLRs), which are crucial for recognizing microbial components and initiating appropriate immune responses. By activating these TLRs, probiotics can modulate various immunomodulatory functions, thereby contributing to a more balanced and effective immune system (Fitzgerald and Kagan, 2020; Li et al., 2022). This interaction underscores the complex and beneficial relationship between probiotics and the host's immune defense mechanisms, highlighting the potential of probiotics in enhancing immune health and preventing immune-related diseases. In the case of salted cabbage, widely consumed in Asian countries, the primary bacterial species involved in the fermentation process include Leuconostoc mesenteroides, Lactiplantibacillus plantarum, Levilactobacillus brevis, Pediococcus pentosaceus, and Enterococcus (Caballero et al., 2016; Kwon et al., 2014; Van Alfen, 2014). These bacteria exhibit anti-inflammatory activity through various mechanisms, such as partially suppressing the production of pro-inflammatory cytokines (like TNF-α and IL-1β) and inhibiting the generation of pro-inflammatory cytokines (Peñas et al., 2012).

Fig. 2.

Immunomodulatory and health-enhancing properties of probiotics derived from fermented foods

LAB are increasingly acknowledged for their capacity to mediate immunological hypersensitivities, notably in allergic manifestations. The domain of atopic dermatitis (AD) stands as a focal point of investigation within allergic disease research, positioning probiotics as viable agents for immunomodulation-based therapeutic interventions. Notably, a study involving Latilactobacillus sakei probio 65, extracted from Kimchi, a quintessential Korean fermented delicacy, demonstrated significant findings. The oral administration of this probiotic strain, in both viable and heat-inactivated states, to NC/Nga mice, yielded a pronounced reduction in AD-like dermal afflictions and a concurrent suppression in mast cell activation (Kim et al., 2013). Additionally, the Lactiplantibacillus plantarum IS-10506 strain, isolated from Dadih, a traditional fermented buffalo milk in Indonesia, has been identified to offer functional benefits to humans, specifically as a therapeutic agent for children with atopic dermatitis (Prakoeswa et al., 2017).

Conclusively, within the context of immune modulation and anti-inflammatory properties, the strategic incorporation of probiotic-enriched substrates into dietary practices not only fortifies gastrointestinal health but also exerts profound immunomodulatory impacts, thereby underscoring their indispensable role in the promotion of human health (Yan and Polk, 2011). This synergistic action is facilitated by the probiotics capacity to orchestrate a balanced Th1/Th2(helper T cells) immune response, coupled with their ability to attenuate allergen-specific Immunoglobulin E (IgE) and reduce the infiltration of mast cells and eosinophils (Llewellyn and Foey, 2017; Zhang et al., 2022). Moreover, the induction of regulatory Treg cells with inherent immunosuppressive functions by probiotics plays a pivotal role in dampening allergic responses, as depicted in Fig. 2, offering a promising avenue for allergy management and immune system regulation.

Synthesis of vitamins and bioactive compounds by LAB derived from fermented foods

The fermentation process results in the removal of the antinutrients from the food while leading to the production of vitamins, minerals, enzymes, and biologically active peptides (Nithya et al., 2023). Within the sphere of nutritional science, the capacity of probiotics to synthesize essential vitamins and a diverse spectrum of bioactive compounds, including organic acids and bacteriocins, underscores their significant role in advancing health and nutrition (LeBlanc et al., 2013; Willing and Van Kessel, 2010). Vitamins are typically categorized as fat soluble vitamins, which include vitamins A, D, E, and K, or as water soluble vitamins, which include vitamin C, biotin (vitamin H or B7), and a series of B vitamins thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), folic acid (B11), and cobalamin (B12) (Basu and Dickerson, 1996; Gu and Li, 2016). Investigations into the vitamin-producing capabilities of probiotics have been a consistent theme in scientific inquiry. Among these studies, the role of lactic acid bacteria, a prominent group within food microbiology, in synthesizing folate and various B vitamins has been extensively documented (LeBlanc et al., 2011). Many probiotic strains, including Limosilactobacillus reuteri, Limosilactobacillus fermenteum and Bifidobacterium longum, particularly from the lactic acid bacteria group, possess the genetic ability to synthesize B vitamins, such as B12 (cobalamin), B9 (folate), B2 (riboflavin), and B1 (thiamine) (Burgess et al., 2009; Hamzehlou et al., 2018; LeBlanc et al., 2011).

In addition to their crucial role in synthesizing a range of essential vitamins, probiotics, particularly those harnessed from fermented foods, are also instrumental in the production of various bioactive compounds. These compounds, including organic acids like lactic and acetic acids, bacteriocins, and SCFAs, play pivotal roles in human health (Fig. 2) (Matar et al., 2000; Mathur et al., 2020). Bacteriocins are antimicrobial peptides produced by bacteria, inhibiting specific strains, and are deemed safe for human consumption due to their non-toxicity to eukaryotic cells and ease of degradation by proteolytic enzymes, presenting a high potential for use as food additives (Ołdak and Zielińska, 2017). Moreover, SCFAs, produced through the fermentation of dietary fibers by probiotics, are essential for maintaining gut health, regulating energy metabolism, and modulating the immune system (Ríos-Covián et al., 2016). Likewise, metabolites such as Gamma-Aminobutyric Acid (GABA), synthesized by specific probiotic strains, play a crucial role in neurological health by acting as inhibitory neurotransmitters, potentially improving brain disorders and enhancing mood stability, thereby broadening the scope of probiotic benefits beyond mere gastrointestinal health (Kittibunchakul et al., 2021). These findings about the diverse roles of probiotics highlight their substantial promise in promoting nutritional health and therapeutic interventions.

For example, Lactiplantibacillus plantarum strains WiKim83 and WiKim87, isolated from kimchi, demonstrate a wide array of bioactive effects, including strong antimicrobial properties against pathogens, enhanced lactose digestion through β-galactosidase activity, and significant antioxidant capabilities to counter oxidative stress (Jung et al., 2019). Lacticaseibacillus rhamnosus strains, isolated from naturally fermented dairy products such as cheese in China, are known to produce bacteriocins, which are antimicrobial substances that effectively inhibit the growth of pathogenic bacteria, including Escherichia coli, Staphylococcus aureus, Salmonella enterica Typhimurium, Listeria monocytogenes, and Enterococcus faecalis (Azat et al., 2016). The exploration of bioactive compounds produced by probiotics isolated from fermented foods, as summarized in Table 2, underscores their potential health benefits. Probiotic strains derived from fermented foods have been identified to produce a variety of bioactive compounds, offering a broad spectrum of health benefits, from cholesterol reduction and neuroprotection to antimicrobial activities and immune modulation (Table 2). These naturally occurring probiotic strains generate a variety of bioactive molecules, including enzymes, peptides, and organic acids, which have been shown to support health in various ways. The ongoing identification and characterization of such strains from fermented food sources are essential for leveraging their health-promoting properties and exploring their application in enhancing food preservation and developing functional foods with specific health advantages.

Table 2.

Health-enhancing properties of bioactive compounds by probiotic strains in fermented foods

No	Fermented food	Study types	Strain	Synthesis of vitamins and bioactive compounds	Symptoms improvement	References
1	Kimchi	In-vitro	Levilactobacillus brevis	GABA	Produced GABA and antioxidant activites	Lee et al. (2021)
2	Chinies Pickled	In-vitro	Lactiplantibacillus plantarum, Levilactobacillus brevis, Weissella viridescens	Bile salt deconjugation	Cholesterol assimilation ability	Liu et al. (2021a)
3	Koosh and Gherkins	In-vitro	Lactobacillus crispatus subsp. crispatus GI9, Weisella koreensis FKI21	In vitro inhibitory activity against tested pathogens and able to deconjugate bile salts	Cholesterol reduction	Rodzi and Lee (2021)
4	Kimchi	In-vitro	Lactococcus raffinolactis	Vitamin B3 (niacin) and *surface protein	Antioxidant activities and adhere to the epithelial cell	Jung et al. (2020)
5	Thai pickled weed	In-vitro	Lactiplantibacillus pentosus	GABA and phenolic compounds producing	Antioxidant activites	Kittibunchakul et al. (2021)
6	Kimchi	In-vitro	Pediococcus pentosaceus K23‐2	Class II bacteriocin	Antimicrobial activity against Gram‐positive bacteria, especially Listeria monocytogenes	Shin et al. (2008)
7	Traditional fermented milk	In-vitro	Lentilactobacillus kefiri, Limosilactobacillus fermentum NF4, Lacticaseibacillus rhamnosus	Produced SCFAs and magnesium and calcium	Cholesterol reduction and immunomodulation	Ismael et al. (2022), Kang et al. (2021)

^*Surface protein: include glyceraldehyde-3-phosphate dehydrogenase, triosephosphate isomerase, trehalose, and maltose hydrolases (possible phosphorylases), beta-galactosidase, lipoprotein signal peptidase, and sortase (surface protein transpeptidase)

Summary

This comprehensive review underscores the multifaceted role of LAB derived from a diverse range of fermented foods, revealing their extensive potential in enhancing human health. The beneficial impacts of these probiotics include promoting gastrointestinal well-being, improving the gut microbiome, and exerting significant immunomodulatory and anti-inflammatory effects. LAB from fermented foods like kimchi, pickled vegetables, and dairy products, through the production of bioactive compounds such as SCFAs, GABA, and bacteriocins, contribute not only to the nutritional enrichment of the diet but also to the management of metabolic and gastrointestinal disorders.

Furthermore, the presence of these probiotics in traditional diets aligns with modern health trends that emphasize the importance of natural and functional foods (Marco et al., 2017). In the same vein, the role of probiotics extends to enhancing food safety, serving as natural preservatives within traditional foods by inhibiting the growth of spoilage and pathogenic microorganisms. This not only improves the safety and shelf life of these foods but also maintains their nutritional integrity (Amenu and Bacha, 2023; Parvez et al., 2006b). The exploration of these traditional food systems is paving the way for innovative processing methods and the inclusion of these functional probiotics in new food products that meet modern safety standards. For example, various omics technologies, such as metagenomics, proteomics, and metabolomics, allow for the detailed analysis of microbial community structures in fermented foods. These techniques enable the evaluation of microbial composition and functional potential, supporting the growth of desirable microorganisms during the fermentation process of different Asian fermented foods (Mannaa et al., 2021b). This, in turn, offers the potential to maintain the quality of fermented foods over extended periods, playing a significant role in the field of food science. Additionally, gene-editing technologies like CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9) can be employed to edit genes that pose safety concerns, such as antibiotic resistance genes. Through CRISPR/Cas9-based technologies, it is possible to produce genetically stable strains, thereby improving the starter cultures used in the fermentation of Asian foods (Vilela, 2021). However, these innovative technologies for LAB in fermented foods are often expensive and face practical issues like those associated with GMO (Genetically Modified Organism), thus limiting their research in the field of food science. Nevertheless, as the extensive potential of LAB in enhancing human health continues to be emphasized, future advancements in the efficiency and safety of these technologies are expected to make more significant contributions to the fields of food science and biotechnology.

The information provided by this review highlights the importance of fermented foods as a natural source of health-enhancing probiotics, advocating for their inclusion in the diet as a proactive approach to maintain health and prevent disease. The therapeutic potential of LAB, particularly for the management of immune-related conditions and improvement of digestive health, establishes these microorganisms as crucial contributors to the field of preventive nutrition and therapeutic microbiology.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.