Fruits as a preventative strategy: exploring their role in neurodegenerative disease management

ABSTRACT

Fruits’ popularity has grown due to their ability to protect against neurodegenerative illnesses and to be an important dietary component for good brain activity. This review focuses on fruits’ potential for preventing such, taking into account their bioactive compounds and mode of action. It emphasizes the abundance of flavonoids, polyphenols, vitamins, and minerals found in berries, citrus, and other tropical fruits, which have been shown to reduce oxidative damage, prevent neuroinflammation, and improve synaptic plasticity. There is an extensive literature on the neuroprotective actions of compounds such as resveratrol, quercetin, and anthocyanins in neurogenesis and mitochondrial process functions. The review also mentions emerging literature with the gut-brain axis, where it underscores the way in which fruit-derived prebiotics and dietary fibers regulate gut microbiota, which in turn affects brain health. This study analyzes gaps by adopting a comprehensive approach to studying fruits’ preventive power in the treatment of neurodegenerative illness. This study combines molecular biology, clinical trial, and dietary science findings to highlight the use of fruits in ordinary diets as a sustainable, natural way of promoting neuroprotection and slowing the course of NDs.

Graphical abstract

1. Introduction

Alzheimer’s, Parkinson’s, and Huntington’s disease neurodegenerative diseases (NDs) are major causes of disability and dependency among the aged around the world [1,2]. They are progressive neurological illnesses characterized by cognitive dysfunction, movement disability, and permanent neuron loss. Despite significant progress in understanding their origin, therapeutic choices remain restricted. As the chronic infections increases in an alarming rate, there is a need for the cost effective methods. Fruits, being the most promising therapeutic alteration for natural foods. Fruits comprises variety of biologically active compounds with anti inflammatory, and neuroprotective ability which highly associated with increased cognitive function and the avoidance of chronic illnesses [3,4]. Recent scientific advancement has paved the way for the study of fruits as a prevention and therapy method for NDs, showing a novel and noninvasive approach to combating the destruction caused by these limiting conditions. The neurodegenerative pathways are complicated, with several causes including oxidative stress, chronic neuroinflammation, mitochondrial failure, and protein misfolding [5]. These pathogenic traits disturb brain homeostasis, resulting in synapse loss and neuronal death. Flavonoids, vitamins, minerals and polyphenols are found in fruits which provides effective protection against degenerative processes [6]. Flavonoids like quercetin and anthocyanins exhibit free radical scavenging activities, as well as neuronal membrane protection and modulation of cellular signaling pathways required for neurogenesis and synaptic plasticity [7]. Resveratrol and other polyphenols have neuroprotective properties because they improve mitochondrial function, reduce amyloid-beta, and modulate inflammation-related signaling pathways [8]. More recent study has shed light on how fruits affect the gut-brain axis, a two-way communication network connecting the gastrointestinal tract and the central nervous system. Fruits’ dietary fiber and prebiotics have been shown to modify gut microbiota composition, increasing the generation of short-chain fatty acids and other metabolites that improve brain function [9]. This interaction also demonstrates the ability of fruits to not only heal neurodegeneration at the molecular level, but also to improve cognitive resilience overall via modifying gut microbiota composition. Some fruits, including berries, citrus, and tropical fruits, have been identified as promising candidates in neuroprotection research due to their high bioactive component concentration [10]. Blueberries and strawberries, which contain anthocyanin-related chemicals, have demonstrated encouraging outcomes in preclinical and clinical cognition enhancement investigations [11]. Citrus fruits strong in vitamin C and flavonoids (hesperidin) may also act as anti-inflammatory drugs, providing significant neuroprotective activity by inhibiting neuroinflammation. Mangoes and guavas are examples of tropical fruits that contain carotenoids, a common dietary antioxidant that improves neuronal integrity [12]. Fruits’ neuroprotective effect is not restricted to laboratory research; clinical trials are now being conducted to evaluate their effectiveness in everyday settings. Dietary therapy based on fruits have been shown to improve cognitive function, lower oxidative stress biomarkers, and increase brain connections in older persons [13]. However, limitations exists in composition variation, bioactive components bioavailability, and heterogeneity of metabolic activities among individuals. The use of fruits in personalized dietary regimens provides a cost-effective and long-term approach to neuroprotection [14,15]. This is accomplished by combining dietary science with molecular biology techniques, which have the ability to bridge substantial knowledge and research gaps in the prevention and management of NDs. Furthermore, research on fruit-derived bioactive compounds as natural therapy proves effective for improving and optimizing the efficacy of current treatments while reducing the risk of side effects [16]. Finally, the use of fruits as a preventive agent in the treatment of neurodegenerative illnesses is an interesting area to investigate and implement. In conclusion, this review emphasizes the importance of incorporating fruits into daily diets as a general intervention to improve brain health and reduce the burden of neurodegenerative disorders by combining molecular biology techniques, clinical findings, and diet science.

2. Antioxidants and neuroprotective mechanisms in fruits

Fruits are rich in antioxidants such as flavonoids, carotenoids, and polyphenols, which protect neurons from oxidative stress and inflammation [17]. Oxidative stress is caused by an imbalance between reactive oxygen species (ROS) and the body’s ability to neutralize them [18]. Such an imbalance is strongly related with the analysis of neurodegenerative disorders such as Alzheimer’s and Parkinson’s. Fruits are rich in antioxidants, which neutralize ROS, limit lipid peroxidation, and so maintain cellular integrity [19]. Flavonoids have been isolated from berries, citrus fruits, and apples. Indeed, products show encouraging results in terms of synaptic plasticity and neurogenesis [20]. Quercetin and anthocyanins, for example, influence signal transduction in brain cells by activating mitogen-activated protein kinase (MAPK) and phosphoinosytol‐3 phosphate/Akt (PI3K-Akt) during the survival and repair processes. Carotenoids present in fruits like mango and papaya, such as beta-carotene and lutein, are also extremely useful since they may be able to cross the blood–brain barrier and decrease oxidative and neurological damage [21]. Fruit-derived compounds have more than only antioxidant properties. Indeed, these compounds have strong anti-inflammatory properties, which are critical for neuroprotection. Neuroinflammation, which is often produced by prolonged oxidative stress, accelerates neuronal death in NDs [22]. Resveratrol, a polyphenol found in grapes and berries, can block pro-inflammatory cytokines including tumor necrosis factor -α (TNF-α) and Interleukin 6 via (IL-6) modulating Nuclear Factor-kappa B (NF-κB) pathways. Other citrus fruits strong in vitamin C and hesperidin prevent microglial activation, hence reducing inflammation produced by neuronal injury [23]. These bioactive compounds not only protect against oxidative and inflammatory damage, but they also improve mitochondrial function and neurotransmitter balance, which are critical for cognitive health.

2.1. Antioxidants: flavonoids, carotenoids, and polyphenols

Antioxidants serve an important function in reducing oxidative stress, which has been linked to the pathogenesis and etiology of neurodegenerative disorders [24]. Fruits include bioactive substances such as flavonoids, carotenoids, and polyphenols, which have strong antioxidant properties and reduce oxidative damage in neural cells. Flavonoids are a large class of polyphenolic substances found in fruits like berries, citrus fruits, and apples [25]. It contains subclasses such as flavanols, flavones, and anthocyanins, which enhance neuroprotection by scavenging ROS and boosting the endogenous antioxidant defense system [26]. Flavonoids also help neurons survive by regulating neurogenesis-related signaling pathways. Quercetin and kaempferol, among other flavonoids, have been linked to decreased cognitive decline and improved synaptic plasticity [27]. Carotenoids, found in fruits like oranges, papayas, and mangoes due to their vibrant colors, have greater neuroprotective properties. The most prominent carotenoids are lutein and zeaxanthin, which accumulate in brain regions and have been demonstrated to reduce lipid peroxidation of neuronal membranes [28]. Their antioxidant activity is complemented by anti-inflammatory activity, making them essential for brain function. Resveratrol, curcumin, and catechin are the three most common polyphenols found in fruits including grapes, apples, and pomegranates [29]. These exhibit bimodal neuroprotective effects, reducing oxidative stress while modifying mitochondrial activity. Resveratrol has also been demonstrated to influence mitochondrial biogenesis, energy metabolism, and apoptosis, all of which play critical roles in brain integrity. Furthermore, there is growing evidence that these antioxidants work synergistically in fruits, strengthening their neuroprotective efficacy [30]. For example, an anthocyanin-catechin combination has been demonstrated to reduce amyloid-beta aggregation, a fundamental pathogenic process in Alzheimer’s disease, while also increasing antioxidant enzyme activity in brain tissues [31]. Although promising, these compounds have challenges such as bioavailability and metabolism. The potential of fruit for neurodegenerative disease through natural, renewable pathways: healthy brain aging, is being explored through advances in improving delivery and efficacy, new formulations like nanoencapsulation, and innovative dietary supplementation approaches. Table 1 outlines the neurodegenerative disorders, the specific flavonoids used and the models employed in studies.

Table 1.

Fruits, specific flavonoids, and their neuroprotective effects.

Fruit	Flavonoid	Mechanism of action	Impact on neurodegeneration	Bioavailability	References
Blueberries	Anthocyanins	Reduces oxidative stress and increases antioxidant enzyme activity.	Decreases amyloid-beta aggregation in Alzheimer	Moderate to High	[32]
Apples	Quercetin	Modulates NF-κB signaling, reduces inflammation	Protects hippocampus neurons and inhibits motor deterioration.	Moderate	[33]
Grapes	Resveratrol	Enhances mitochondrial biogenesis, decreases IL-6 levels	Improves cognitive flexibility, reduces oxidative stress	High	[34]
Strawberries	Vitamin C	Scavenges ROS, neutralizes reactive species	Protects neuronal membranes, reduces TNF-alpha	Moderate to High	[35]
Mangoes	Zeaxanthin	Inhibits neurodegeneration pathways, protects brain cells	Enhances learning skills, reduces amyloid plaques	Moderate	[36]
Papayas	Lutein	Protects brain cells, reduces oxidative burden	Improves synaptic function, decreases IL-10	Moderate	[37]
Pomegranates	Ellagic Acid	Prevents oxidative bursts, enhances DNA repair	Reduces cytokine storms, protects neuronal integrity	Moderate	[38]

2.2. Effects on inflammation and oxidative stress

Alzheimer’s, Parkinson’s, and Huntington’s disease are all associated with persistent oxidative stress and inflammation, which contribute to neuronal death and cognitive impairment [39]. Fruits include bioactive compounds such as flavonoids, polyphenols, carotenoids, and vitamins, which play important roles in disease processes [40]. Oxidative stress is induced by an imbalance in the formation of reactive oxygen species and antioxidant defense systems, which leads to neuronal lipid peroxidation, protein denaturation, and DNA damage [41]. Fruit polyphenols, such as quercetin, anthocyanins, and catechins, inhibit the production of ROS. Blueberries and blackberries, for example, contain anthocyanins, which scavenge free radicals and boost the activity of natural antioxidant enzymes like superoxide dismutase (SOD) and catalase [42]. These chemicals also improve mitochondrial function, preventing energy deficit and neuronal death. Neurodegeneration is also characterized by inflammation in the brain, such as activated astrocytes and microglia. Chronic neuroinflammation impairs synaptic plasticity, slows neurogenesis, and increases oxidative damage. Citrus fruits include hesperidin and naringenin, which regulate NF-κB and MAPK pathways, resulting in decreased production of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 [43]. Resveratrol, a grape polyphenol, controls microglial activation, switching from pro-inflammatory (M1) to anti-inflammatory (M2) phenotypes and providing neuroprotection [44]. Current study highlights the synergistic effects of many bioactive compounds in fruits. Citrus fruits include vitamin C, which directly scavenges free radicals and recycles oxidized vitamin E, thereby increasing antioxidant capacity. Other polyphenols in green tea, such as epigallocatechin gallate, have synergistic effects that improve antioxidant defense and anti-inflammatory activity [45]. Clinical trials have also shown that fruit-based therapies can be therapeutically effective. A Mediterranean diet high in fruits has been linked to lower levels of oxidative stress and systemic inflammation, as well as lower rates of cognitive loss in sensitive individuals [46]. However, various issues concerning the bioavailability and metabolism of these bioactive chemicals are discussed, implying that new, more effective delivery techniques, such as nanoformulations, must be created in order to produce a greater therapeutic impact. Fruits are particularly important dietary ingredients in avoiding neurodegenerative diseases due to their antioxidant and anti-inflammatory properties [47]. Understanding their bioavailability and molecular processes will allow them to be employed in tailored nutritional strategies for neuroprotection. Figure 1 illustrates the progression of inflammation in neurodegenerative disorders.

Figure 1.

Mechanisms and effects on inflammation in neurodegenerative diseases.

Legend: Figure 1 illustrates the progression of inflammation in neurodegenerative disorders. Alterations in homeostasis may exacerbate neurodegenerative disorders. Immune signaling system dysregulation may exacerbate oxidative stress and inflammation in disorders such as multiple sclerosis, Parkinson’s disease, and Alzheimer’s disease, compromising brain survival and function. Dysregulation of these pathways may contribute to neurodegenerative illnesses, including metabolic abnormalities, neuronal damage, and persistent neuroinflammation.

3. Fruits and their role in reducing neuroinflammation

Neuroinflammation seems to play a significant role in the pathophysiology of neurodegenerative disorders such as Alzheimer’s, Parkinson’s, and Huntington’s. Brain inflammation typically causes neuronal damage, cognitive impairment, and worsening of these disabling disorders [48]. Fruits, with their unique bioactive compounds, have emerged as a new natural source of anti-inflammatory activity and brain health improvement. Fruits also include anti-inflammatory chemicals such flavonoids, polyphenols, and carotenoids, which directly affect inflammatory pathways [49]. Flavonoids like quercetin and kaempferol can prevent the activation of pro-inflammatory cytokines like TNF-α and IL-1β. Polyphenolic chemicals present in berries, like as anthocyanins, control microglial activation with minimal damage while maintaining immune surveillance function [50]. These pathways point to the possibility of fruits as nutritional therapies in the treatment of chronic brain inflammation. New research suggests that fruit metabolites can decrease the NF-κB pathway, a key regulator of inflammation. Suppressing NF-κB signaling reduces the generation of inflammatory mediators, protecting neurons and enhancing synaptic function [51]. It also takes into account individual fruits like blueberries, strawberries, and citrus fruits, as well as their bioactive compounds and mechanistic anti-inflammatory properties.

3.1. Modulating neuroinflammation

Fruit compounds modulate neuroinflammation via numerous routes. It would involve immune cell regulation, reduction of pro-inflammatory indicators, and enhanced antioxidant defense systems [52]. In neurodegenerative illnesses, active microglia produce pro-inflammatory cytokines and ROS, which contribute to oxidative stress and neuronal damage. Pomegranate and grapes, which are high in antioxidants, can assist to interrupt this vicious cycle [53]. Pomegranate ellagitannins are converted in the gut to urolithins, which have anti-inflammatory and cyclooxygenase inhibitory properties that reduce oxidative damage [54]. Resveratrol-rich grape skin and seeds alter sirtuin-1‘s inflammatory activity and lessen the impact of oxidative stress. Recent research has shown that fruit bioactives have the capacity to target specific brain regions damaged by NDs. Citrus flavonoid hesperidin reduces neuroinflammatory markers IL-6 and TNF-α, providing protection for the hippocampus [55]. Furthermore, curcuminoids from turmeric, when added to fruit-based smoothies or blends, have been shown to suppress amyloid plaque formation and microglial activation, both of which are important in Alzheimer’s pathology [56]. The gut-brain axis expands the scope of fruit-mediated control of neuroinflammation. Prebiotics and dietary fibers found in bananas, apples, and kiwis increase the generation of SCFAs by gut microbiota, which reduce systemic inflammation and protect the blood–brain barrier [57]. This indirect mechanism demonstrates the systemic effect of fruits on brain health [58]. Figure 2 depicts fruits and their involvement in decreasing neuroinflammation.

Figure 2.

Fruits and their role in reducing neuroinflammation.

Legend: Figure 2 depicts fruits and their involvement in decreasing neuroinflammation. Fruits are high in antioxidants, vitamins, and polyphenols, which neutralize reactive oxygen species and inflammation in the brain, making them essential for neuroinflammation reduction. Including fruits in diets will help avoid neurodegenerative illnesses caused by chronic neuroinflammation and improve brain health.

4. Gut-brain axis: the effect of fruit on improved cognitive health

The gut-brain axis (GBA) is a duplex communication link between the CNS and the gut [58]. This complex connection has significant consequences for cognitive health, mood, and the cause of neurodegenerative illnesses. Current research has identified fruit components as important modulators of this axis; fruits influence gut microbiota and thus brain function. Fruits dispense prebiotic fibers, polyphenols, vitamins, and other bioactive components that enhance gut microbial health and richness [59]. Prebiotics, which include pectin found in apples and citrus fruits, operate as substrates for gut health-promoting bacteria, increasing the proliferation of important microbial species such as Bifidobacterium and Lactobacillus [60]. These microorganisms synthesis short-chain fatty acids (SCFAs) such as butyrate, acetate, and propionate, which are known to strengthen the intestinal barrier, reduce inflammation, and enhance neuroprotection. Butyrate reduces pro-inflammatory cytokines such as IL-6 and TNF-α, which induces neuroinflammation and cognitive dysfunction [61]. Polyphenols found in berries, grapes, and citrus fruits have a dual effect on the GBA, interacting directly with gut bacteria while also plays a vital role in modifying neuronal pathways. Resveratrol, a polyphenol found in grapes and berries, enhances SCFA production and also regulating brain-derived neurotrophic factor (BDNF), a protein vital for neurogenesis and synaptic plasticity. Quercetin and anthocyanins reduce oxidative stress and improve mitochondrial function, which is essential for neurons and their functions [62]. The gut microbiota also communicates with the brain using the vagus nerve and microbial metabolite signaling. Fruit-derived polyphenols have been shown to activate the vagus nerve, which sends anti-inflammatory signals that reverse neuroinflammation [63]. Furthermore, microbial metabolites such as tryptophan metabolites influence serotonin levels in the central nervous system, which affects mood, memory, and cognitive function. Fruits, such as bananas, are rich in tryptophan and vitamin B6, which are implicated in the production of serotonin and hence relate food with mood. The same principle contends that consuming fruits helps to prevent dysbiosis, an imbalance of gut bacteria that has been linked to NDs including Alzheimer’s and Parkinson’s disease [64]. According to study, polyphenol-rich fruit diets, such as blueberries, have the potential to rectify microbial imbalances, prevent amyloid-beta aggregation, and improve cognitive results in preclinical animals [65]. More research is needed on the bioavailability of bioactives from fruits, interindividual variance in microbiota composition, and the long-term cognitive function implications of a fruit diet. Finally, fruits control the GBA, making them a natural, long-term strategy to improve cognitive health [66]. Fruits have significant promise as disease-preventative agents against neurodegenerative disorders because they help balance gut flora and reduce neuroinflammation, thus including them in daily meals is vital. Figure 3 demonstrates how fruit improves cognitive health in the gut-brain axis.

Figure 3.

The effect of fruit on improved cognitive health on the gut-brain axis.

Legend: Figure 3 demonstrates how fruit improves cognitive health in the gut-brain axis. The gut-brain connection circuit responds to dietary changes. Nutrition has the ability to influence gut-brain communication via hormonal, immunological, metabolic, neuronal, and microbial metabolites. Fermented foods, fiber, and polyphenols can be combined to create a balanced diet that supports beneficial microorganisms. These bacteria have the potential to be involved in neurotransmitter production and bioactive chemicals.

5. Neurodegenerative diseases and neuroprotective fruits

Neurodegenerative diseases (NDs) are progressive, chronic disorders that cause the central nervous system’s structure and function to deteriorate over time. The dysfuctional physiology of the disorders includes neuroinflammation, oxidative stress, and mitochondrial dysfunction, which induces neuronal damage and cell death [67]. As a result, intensive research on developing new effective treatments capable of slowing disease progression by reducing these mechanisms. The most promising therapeutic leads are fruits, particularly antioxidant rich fruits, which have been shown to have neuroprotective properties. Common neurodegenerative conditions results from neuronal death and loss of cognition due to amyloid-beta plaque formation and tau tangles [68]. Berries, specifically blueberries and strawberries, are high in antioxidants. Berries contain flavonoids such anthocyanins, which have been proven to reduce amyloid-beta aggregation, enhance neurogenesis. Intensive research have demonstrated that daily consumption of blueberries increases hippocampal function, lowers oxidative stress, and reduces neuronal cell death linked with Alzheimer’s disease pathogenesis [69]. The loss of dopaminergic neurons in the substantia nigra results in Parkinson's disease, therefore leading to movement dysfunction. Apples and grapes are among high-polyphenolic category, which have shown to protect dopaminergic neurons [70]. These fruits include chemicals with neuro protective effects like as quercetin and resveratrol, which have been proven to lower oxidative stress, limit neuroinflammation, and inhibit ROS production. Moreover, resveratrol found in grapes, has been shown to activate sirtuins, enzymes that controls cellular stress responses and mitochondrial function, both of which are crucial in the prevention of neurodegeneration [71].

Huntington’s disease is caused by a mutation in the huntingtin gene, which results in the loss of basal ganglia neurons, as well as motor and cognitive dysfunction [72]. Pomegranate, apples and cherries contain polyphenolic substituents demonstrated for their medicinal potential in reducing oxidative stress and neuroinflammation in HD. Ellagic acid and anthocyanins, have been shown to alter antioxidant enzyme expression and inhibit mitochondrial dysfunction, slowing the development of HD by inducing cell death. As amyotrophic lateral sclerosis advances, motor neurons are gradually lost, followed by muscle atrophy and respiratory failure [73]. Although the mechanism is not specific, most of the research suggest that oxidative stress and inflammation play a potential role. Citrus fruits are rich in vitamin C and flavonoids, which have been shown to be neuroprotective by scavenging free radicals, reducing inflammation, and boosting the activity of antioxidant enzymes. This could potentially slow down the progression of amyotrophic lateral sclerosis and improve patients’ life [74]. Recent research has examined that various bioactive chemical-rich fruits have neuroprotective properties and can improve numerous underlying processes that cause dementia. These compounds help prevent oxidative damage by scavenging reactive oxygen species and elevating the body’s natural antioxidant defenses. Anthocyanins found in Berries’ lowers oxidative stress and inflammation, both of which contribute to the progression of neurodegenerative disorders. Apart from antioxidant properties, fruits influence a variety of neuroprotective signaling pathways. Polyphenols in grapes and apples, for example, have been proven to prevent the aggregation of misfolded proteins, which is associated to disorders such as Alzheimer’s [75]. Citrus flavonoids have been shown to decrease neuroinflammation by modulating microglial activation and cytokine production, reducing the inflammatory burden on the brain [76]. Furthermore, consumption of fruits has been related to regulation of neurogenesis and synaptic plasticity, both of which are vital processes for cognition and memory. Fruits may decrease the initiation of neurodegenerative illnesses by stimulating the formation of new neurons and strengthening synaptic connections [77]. Regular intake of these neuroprotective fruits is a promising supplemental therapy for the treatment of chronic diseases and the improvement of overall cognitive function.

The Nrf2 (nuclear factor erythroid 2-related factor 2) signaling pathway is a vital regulator of the cellular response to oxidative stress and contributes significantly in neuroprotection [78]. This promotes the transcription of antioxidant response elements (AREs) in genes that encode vitagenes, which are essential for redox homeostasis and cellular resilience. Vitagenes such as heme oxygenase-1 (HO-1), thioredoxin, and heat shock proteins (HSPs) function as molecular chaperones, shielding cells from oxidative and inflammatory stress [79]. The Nrf2-vitagenes axis is significantly important for the prevention of neurodegeneration illness as it mitigates oxidative stress, suppresses inflammation, and elevates cellular repair mechanisms. Nrf2 activation in neurodegenerative disorders has been demonstrated to reduce neuronal apoptosis, increase mitochondrial metabolism and reverse ROS formation [80]. Fruits activate Nrf2 pathway with bioactive compounds such as polyphenols, flavonoids, and carotenoids, promoting its neuroprotective benefits. Nrf2 nuclear translocation is initiated by resveratrol, a polyphenol found in grapes and berries, which boosts the activity of antioxidant enzymes like as superoxide dismutase (SOD) and glutathione peroxidase. Similarly, quercetin, found in citrus fruits, activates the Nrf2 pathway, which lowers neuroinflammation and oxidative stress. The combined activity of these chemicals increases the Nrf2-related resilience network, providing a molecular mechanism for fruits’ neuroprotective properties. The interaction of vitagenes with the Nrf2 pathway further specifies the potential of fruit bioactives in the protection of neurodegenerative disorders. Bioactives regulates the resilience network, neutralizing not just oxidative stress but also neuronal survival and metabolism, resulting in better cognitive well-being and delayed disease mechanisms. The research studies suggests that incorporating fruits in diets is crucial as a potential natural therapy for improving neuroprotection and resilience to neurodegenerative illnesses. Table 2 provides an exhaustive overview of specific flavonoids derived from various fruits and their impact of NDs.

Table 2.

Neurodegenerative disorders, flavonoids, and study models.

Neurodegenerative disorder	Flavanoids	Source	Mechanism of action	Model used	References
Alzheimer’s Disease	Anthocyanins	Blueberries, Strawberries	Improves synaptic plasticity, boosts neurogenesis, and decreases amyloid-beta aggregation	Animal and pre clinical	[81]
Parkinson’s Disease	Quercetin	Apples	Decreases neuroinflammation, shields dopaminergic neurons, and lowers oxidative stress.	Cohort study	[82]
Huntington’s Disease	Resveratrol	Grapes	Minimizes inflammation, boosts mitochondrial activity, and increases Cognitive flexiblity.	Randomised trial	[83]
Amyotrophic Lateral Sclerosis	Dopamine precursors	Bananas	Delays disease progression, reduces oxidative stress	Longitudinal Study	[84]
Dementia	Ellagic acid	Pomegranates	Prevents oxidative bursts and cytokine storms.	Case control study	[85]
Multiple sclerosis	Vitamin C	Strawberries	Improves neuronal function	Randomised trial	[86]

6. Clinical trials on fruit and neurodegenerative diseases

Recent clinical trials have shown that fruits with bioactive components nullify neurological dysfunctions. Polyphenol-rich fruits have been demonstrated in Alzheimer’s disease for their impact on cognitive function and oxidative stress markers. A study found that daily intake with blueberry powder boosted memory and cognitive performance in older people with minimal cognitive impairment [87]. This study reveals that fruits can boost brain health by mitigating oxidative damage and boosting neuroplasticity. Trials with flavonoid-rich citrus fruits, particularly those high in flavanones, showed promise in reducing neuroinflammation associated with neurodegenerative disorders. Consumption of flavonoid-rich fruits has been shown to have a positive effect on delaying the death of dopaminergic neurons, slowing Parkinson’s disease progression [88]. Experiments using other tropical fruits, such as mangoes and papayas, have also shown promise in memory control and oxidative stress reduction. These fruits, particularly those high in vitamin C, were studied for their effects on memory impairment in the elderly and people with neurological illnesses. Preliminary research suggests that consuming antioxidant-rich fruits can be utilized as an adjunctive therapy in the treatment of neurodegenerative illnesses. Large-scale, long-term clinical trials will be necessary to determine the therapeutic benefit and appropriate dose for neuroprotection. Table 3 summarizes the findings of clinical trials on neuro protective effects of fruit-derived bio active compounds.

Table 3.

Clinical trials and role of fruits in neurodegenerative diseases.

Disease	Fruit	Key compound	Study type	Outcome measured	Patient group	Neuroprotective outcome	Reference
Alzheimer’s Disease	Blueberries	Anthocyanins	Clinical Trial	Improved memory retention	Elderly	Reduced beta-amyloid	[89]
Parkinson’s Disease	Apples	Quercetin	Cohort Study	Enhanced motor functions	Middle-aged	Reduced oxidative stress	[86]
Huntington’s Disease	Grapes	Resveratrol	Randomized Trial	Improved cognitive flexibility	Adults	reduced inflammation	[71]
Amyotrophic lateral sclerosis	Bananas	Dopamine Precursors	Longitudinal Study	Delayed disease progression	Mixed Age	Improved motor strength	[90]
Dementia	Pomegranates	Ellagic Acid	Case-Control Study	Enhanced memory recall	Elderly	Decreased cytokines	[91]
Multiple sclerosis	Strawberries	Vitamin C	Randomized Trial	Improved neuronal function	Adults	Reduced TNF-alpha	[92]
Alzheimer’s Disease	Mangoes	Zeaxanthin	Meta-Analysis	Reduced amyloid plaques	Elderly	Enhanced synaptic health	[93]
Dementia	Oranges	Hesperidin	Cohort Study	Improved verbal fluency	Mixed Age	Reduced CRP	[26]
Huntington’s Disease	Papayas	Lutein	Clinical Trial	Enhanced focus	Adults	Improved brain health	[94]

7. Future perspectives

The fruit-based neurological protection has the potential for significant advancement as cellular nutrition, neurobiology, and precision medicine are interwoven. Over the next few years, researchers aim to focus on understanding the challenging chemical interactions between certain fruit bioactives and neurological pathways involved in the genesis and progression of neurodegenerative diseases (NDs). Advances in omics technologies, such as the metabolomics and nutritional genomics, might allow for improved understanding about specific reactions to fruit-derived substances, paving up possibilities for individualized dietary therapies based on one’s genetic and microbial profiles. Furthermore, significant advancements will likely be made to boost the bioavailability and targeted delivery of crucial phytochemicals such as anthocyanins, resveratrol, quercetin, and hesperidin. Nanoformulation and encapsulation techniques have the potential to contribute a revolutionary role in improving the stability, solubility, and blood–brain barrier penetration of these bioactives. Furthermore, long-term, multi-center clinical trials using standardized fruit extracts are required to determine the appropriate dosage, frequency, and duration for the effectiveness of therapy against various NDs. Future research might look into the synergistic benefits of integrating different fruits or incorporating fruit chemicals into current pharmacotherapies to improve neuroprotective outcomes. Furthermore, the increasing importance of the gut-brain axis in cognitive resilience highlights the necessity for long-term studies to investigate how persistent fruit consumption alters gut microbiota, influencing mental health and neurodegeneration. To summarize, fruits are transitioning from simple dietary components to precise nutraceuticals. A multidisciplinary strategy that integrates dietary science, biotechnology, and clinical research will be required to translate fruits’ promising potential into effective, accessible, and long-term solutions for treating neurodegenerative illnesses.

8. Conclusion

Fruits are vital for their role in neuroprotection and the prevention of neurodegenerative disorders. Fruits contain antioxidants that modulate inflammatory cytokine inhibition, free radical scavenging, and mitochondrial activity, which provide a natural potential solution to battle against the oxidative stress and inflammation, which are the primary causes of neuronal pathogenesis. Research supports the neuroprotective function of certain fruits, including blueberries, grapes, strawberries, and citrus fruits, which are associated to bioactive components including as anthocyanins, resveratrol, and hesperidin. For example, anthocyanins in blueberries blocks amyloid-beta aggregation and oxidative stress, whereas resveratrol in grapes elevates function of mitochondria and modulates inflammatory pathways. Citrus hesperidin, which reduces neuroinflammation, also boosts cognitive and memory performance. Because these compounds target numerous disease pathways, fruits have the potential to be dietary treatments for neurodegenerative diseases. Emerging research studies also shows that fruits have regulatory effects on the gut-brain axis, a duplex network that connects the gastrointestinal tract to the central neurological system. Fruit-derived prebiotics and fibers impact the composition of gut microbiota, resulting in the formation of short-chain fatty acids that improves brain health. This association between food, gut microbiota, and brain highlights the overall benefits of fruit consumption for cognitive and neurological function. Despite positive outcomes from preclinical and clinical findings, there remain challenges in transcribing these findings into effective dietary recommendations. Furthermore, determining optimal dosage, fruit combinations, and dietary patterns for high impact of neuroprotection is a future study goal. In conclusion, incorporating fruits in regular diets is a natural, potential, and sustainable strategy to reduce the significance of NDs. Using molecular biology, nutritional science, and clinical studies, this study demonstrates the therapeutic potential of fruits in improving brain function, preventing cognitive impairment, and supplementing existing treatment strategies. Future research must overcome current constraints in order to establish fruit-based dietary treatments as a cornerstone in the prevention and treatment of neurodegenerative disorders. This approach is not only consistent with public health goals, but it is also a practical and cost-effective way to reduce the growing worldwide burden of these disabling conditions.

Funding Statement

This paper was not funded.

Article highlights

1. Introduction to Neurodegenerative Disorders

● Neurodegenerative disorders (NDs) such as Alzheimer’s, Parkinson’s, and Huntington’s are major global health concerns with few therapy choices.

2. Fruits as a Nutritional Strategy Against NDs

● Fruits offer a natural, cost-effective strategy to combat NDs, owing to their rich content of bioactive components.

3. Anti-Inflammatory Effects of Fruits

● Fruits modulate inflammatory pathways by decreasing pro-inflammatory cytokines such as TNF-α and IL-6.

● Polyphenols in fruits like grapes and berries control microglial activation, reducing chronic neuroinflammation

4. Gut-Brain Axis Modulation

● Fruits alter gut microbiota by supplying prebiotic fibers and polyphenols, boosting the formation of neuroprotective short-chain fatty acids.

● Gut-brain axis regulation by fruit bioactives improves cognition and lowers neuroinflammation.

5. Antioxidant and Cognitive Benefits

● Specific fruits including blueberries, grapes, and pomegranates include chemicals that prevent oxidative damage and promote cognitive abilities.

● Resveratrol and anthocyanins reduce amyloid-beta aggregation and mitochondrial dysfunction in NDs.

6. Clinical Evidence and Therapeutic Potential

● Clinical research demonstrate significant gains in memory, cognitive flexibility, and lowered biomarkers of oxidative stress with fruit-derived bioactives.

● Evidence supports utilizing fruits as adjunct therapy for NDs, while problems including bioavailability and long-term consequences remain.

Author contributions

Bhavani Sowndharya B – Writing-original draft; Mathan Muthu C M, Bharath S – Writing & editing; Vickram A S, Hitesh Chopra, and Rupesh K. Gautam: Conceptualization, Investigation, Validation.

Disclosure statement

The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Writing disclosure

No writing assistance was utilized in the production of this manuscript.