Anxiety, depression, and cognitive deficits are among the mental health conditions that greatly increase the worldwide burden of disease. More than 264 million people worldwide suffer from depression alone, according to the World Health Organization (2021), and mental health issues are predicted to increase as a result of sedentary lifestyles, chronic stress, and nutritional imbalances.

The importance of the gut microbiota in determining brain health has come to light in recent years. The human gut's trillions of bacteria affect immunological, neuroendocrine, and metabolic functions; dysbiosis, or imbalances, has been connected to mental health disorders (Cryan et al., 2019). The gut–brain axis (GBA) is the term for this communication between the gut and the brain, which is mediated by immunological signaling molecules, neurotransmitters, microbial metabolites, and neuronal circuits, particularly the vagus nerve (Foster & McVey Neufeld, 2013).

The gut microbiota is significantly impacted by diet. Prebiotics, which are substrates that host bacteria preferentially use to provide health advantages (Gibson et al., 2017), have become potential agents for microbial balance restoration. Inulin, fructo-oligosaccharides, galacto-oligosaccharides, and, more recently, fibers derived from cereals like arabinoxylan are examples of common prebiotics.

Whole grains are rich in arabinoxylan, which has special structural and functional qualities. It ferments in the colon to form SCFAs like butyrate, which have neuroprotective properties and can pass through the blood–brain barrier (Dalile et al., 2019). Arabinoxylan may be used as a dietary intervention to enhance mental health by affecting immunological regulation, neurotransmitter pathways, and microbial diversity.

The potential of arabinoxylan as a prebiotic in relation to mental health is summarized in this review, with a focus on its function within the framework of the gut-brain axis.

1. Research Objective

The primary objectives of this review are to:

1. To Study the biochemical composition and prebiotic properties of arabinoxylan.
2. To cevaluate how arabinoxylan modulates gut microbiota and SCFA production.
3. To explore the mechanisms of the gut-brain axis in mental health regulation.
4. To analyze recent evidence linking arabinoxylan supplementation with improved cognitive function reduced anxiety, and depression.

LITERATURE REVIEW

According to Rajanala, Kumar, and Chamallamudi (2021), trillions of microorganisms from different species and genera are entrenched in the human digestive system. These organisms live in symbiosis with the host and fulfill a variety of functions in the human body. Their primary function is to aid in the breakdown and transformation of food into a variety of beneficial substrates for the human body. In addition to this, the gut bacteria keeps the brain and other body organs in good communication. The gut-brain axis (GBA) refers to the relationship between gut microbiota and the brain, which is mediated via immunological, endocrine, and neurological pathways. They therefore play a role in the neurophysiology and neuropathology of a number of illnesses, including autism, depression, Parkinson's disease (PD), and Alzheimer's disease (AD). Numerous dietary supplements, including probiotics and prebiotics, can alter the makeup of the gut microbiota. The gut microbiota's role in depression and the benefits of probiotics and other supplements for treating depression are reviewed in this article.

According to Marcel et al. (2017), the gut is home to a vast array of microorganisms that are critical to maintaining homeostasis in both health and illness. The idea that this microbiome influences host appetite and food consumption is becoming more and more supported by data. The presence of other bacterial species and the nutrients that are available to them exert selective pressure on individual species within the gut microbiota. Through the specific fermentation of dietary nutrients and the secretion of metabolites, each species of bacteria in the gut seeks to improve its own fitness, habitat, and survival. Many of these metabolites have the ability to directly impact nutrient sensing, appetite, and satiety-regulating systems, thereby influencing host appetite and eating behavior. These include short-chain fatty acids and neuroactives generated by the microbiome. Furthermore, the gut microbiota can affect host antigen production, modify the immune system, interact with bile acid metabolism, and alter intestinal barrier integrity, all of which have an indirect impact on eating habits. An increasing amount of data suggests that the microbiota plays a critical role in controlling various facets of eating-related behavior as well as the behavioral comorbidities of metabolic and eating disorders. Obesity, anorexia nervosa, and severe acute malnutrition have all been linked to the composition of the gut microbiota. Novel biotherapeutic approaches will result from a better understanding of the ways in which the gut microbiota can affect host appetite and metabolism. This understanding will help address illnesses like obesity and other metabolic or eating disorders where hunger is dysregulated.

According to research by Appleton (2018), the gut-brain axis is a network of two-way communication that connects the central nervous system and the gastrointestinal system. This network encompasses not just anatomical pathways but also humoral, immunological, metabolic, and endocrine pathways. The gut can affect mood, cognition, and mental health, while the brain can affect intestinal activities, including the activity of functional immune effector cells, thanks to the autonomic nervous system, the hypothalamic-pituitary-adrenal (HPA) axis, and nerves in the gastrointestinal tract.

Probiotics and prebiotics have been shown to alter the gut-brain axis, which supports central nervous systems and reduces or manages the prevalence of mental illnesses such depression, anxiety, autism, schizophrenia, and Alzheimer's disease (Ansari et al., 2023). Complex interactions between the gut, brain, and microbiota have been covered in this review, along with new research on the effects and potential mechanisms of action of probiotics and prebiotics on mental illnesses. According to the results, probiotics and prebiotics can enhance central nervous system function and are useful in the prevention and treatment of certain brain disorders. However, more research is required, particularly in the form of human studies and clinical trials, to substantiate these effects definitively and to use these substances in a supportive and therapeutic manner.

According to Berding et al. (2021), the gut microbiota has become increasingly important in controlling behavior and brain functions throughout the last ten years. One of the main elements influencing the composition of the gut microbiota during life is diet. However, research is just now starting to look at if and how nutrition can impact the brain through its effects on the microbiota. There are a number of known gut-to-brain communication channels, such as immunological, neuronal, metabolic, and microbial metabolites, some of which may be susceptible to dietary modification. Our knowledge of the role of diet in this reciprocal communication has advanced as a result of animal studies examining the effects of dietary treatments on the microbiota–gut–brain axis. In this review, we examine possible underlying mechanisms and provide an overview of the present status of the literature that triangulates host behavior/brain processes, microbiome, and nutrition. Evidence supporting the microbiome as an underlying modulator of the impact of nutrition on brain health is also presented, along with factors that influence response to dietary interventions. We also highlight the need for more evidence from clinical populations and the understudied application of whole-dietary techniques in this attempt. Although encouraging findings have been published, more information— particularly from clinical cohorts—is needed to support evidence-based suggestions for the creation of whole-dietary, microbiota-targeted interventions to enhance mental and cognitive health.

ARABINOXYLAN: STRUCTURE AND SOURCES

Structural Composition

Hemicellulosic polysaccharides called arabinoxylans are mostly found in wheat grain cell walls. At positions 2 and/or 3, arabinofuranosyl residues are substituted for the β-(1→4)-linked xylopyranosyl residues that make up their backbone (Izydorczyk & Biliaderis, 1995). In certain instances, arabinoxylans are cross-linked by ferulic acid residues via ester linkages, which affects their solubility and fermentability.

The physiological characteristics of arabinoxylans are strongly influenced by the degree of substitution and the ratio of arabinose to xylose (A/X ratio). While insoluble fractions are frequently associated with the bulking effect of dietary fiber, a high A/X ratio improves solubility. The profile of metabolites produced and the pace of fermentation in the colon are determined by these anatomical differences.

Dietary Sources

Arabinoxylan is present in the bran and endosperm of cereal grains. Wheat bran is the richest source, containing 20–30% arabinoxylan by weight (Courtin & Delcour, 2002). Other sources include:

• Rye – contains both soluble and insoluble arabinoxylan.
• Barley – lower content but important due to soluble fractions.
• Corn fiber – used industrially for AXOS production.

Whole-grain products, particularly wheat bran supplements, are therefore practical dietary sources of arabinoxylan.

Arabinoxylan-Oligosaccharides (AXOS)

Arabinoxylan can be enzymatically hydrolyzed into arabinoxylan-oligosaccharides (AXOS), which are shorter, more soluble chains with enhanced prebiotic potential. AXOS are more readily fermented by Bifidobacteria and Lactobacilli, compared to native arabinoxylan, making them ideal for functional foods and dietary supplements (Swennen et al., 2006).

PREBIOTIC ROLE OF ARABINOXYLAN

Mechanistic Basis of Prebiotic Action

To qualify as a prebiotic, a compound must resist digestion in the upper gastrointestinal tract, reach the colon intact, and be selectively fermented by beneficial microbes. Arabinoxylan fulfills these criteria. Upon reaching the colon, it undergoes fermentation by bacteria that release SCFAs, influencing both gut and systemic health.

Microbiota Modulation

Numerous studies show that arabinoxylan and AXOS selectively enhance the growth of beneficial bacteria. Neyrinck et al. (2011) demonstrated that wheat-derived AXOS increased Bifidobacteria while reducing pathogenic species such as Clostridium perfringens. Walton et al. (2012) confirmed similar bifidogenic effects in human trials.

Metabolite Production

Arabinoxylan fermentation leads to SCFA production:

• Acetate – influences cholesterol metabolism.
• Propionate – involved in gluconeogenesis.
• Butyrate – enhances gut barrier integrity, exerts anti-inflammatory effects, and acts as a signaling molecule for brain function (Dalile et al., 2019).

Together, these SCFAs modulate metabolic health while directly impacting brain processes.

GUT–BRAIN AXIS: A BIDIRECTIONAL COMMUNICATION SYSTEM

Overview of the Gut–Brain Axis

The GBA integrates communication between the central nervous system (CNS) and the enteric nervous system. The primary mechanisms include:

• Neural pathways: Microbial signals are transmitted via the vagus nerve.
• Immune pathways: Cytokines produced in the gut influence neuroinflammation.
• Endocrine pathways: Gut microbes modulate stress hormones through the hypothalamic–pituitary–adrenal (HPA) axis.
• Metabolic pathways: Microbial metabolites, particularly SCFAs, cross into circulation and affect brain activity.

Dysbiosis and Mental Health

Dysbiosis disrupts these communication channels, leading to psychiatric outcomes. For example, patients with major depressive disorder often exhibit reduced microbial diversity and lower abundance of butyrate-producing bacteria (Jiang et al., 2015). Restoring microbial balance with prebiotics such as arabinoxylan may normalize these pathways, improving mood and cognition.

MECHANISMS LINKING ARABINOXYLAN TO MENTAL HEALTH

Microbiota Modulation and Behavior

AXOS supplementation not only increases beneficial bacteria but also correlates with behavioral improvements. Liu et al. (2020) reported that mice receiving AXOS showed reduced anxiety-like behavior and improved spatial memory.

SCFA-Mediated Neuroprotection

Butyrate is particularly relevant for mental health. It serves as a histone deacetylase inhibitor, enhancing expression of brain-derived neurotrophic factor (BDNF), a protein critical for neuroplasticity and resilience to stress (Dalile et al., 2019).

Neurotransmitter Regulation

Gut microbes affected by arabinoxylan can produce or influence the availability of neurotransmitters:

• Serotonin (5-HT): About 90% is produced in the gut. Modulation of serotonin precursors impacts mood regulation.
• Dopamine: Influences motivation and reward pathways.
• GABA: Plays a role in reducing neuronal excitability, linked to anxiolytic effects (Strandwitz, 2018).

EXPERIMENTAL AND CLINICAL EVIDENCE

Animal Studies

• Liu et al. (2020) found that AXOS supplementation improved gut microbiota composition, reduced anxiety-like behavior, and increased hippocampal plasticity in mice.
• Other rodent studies have demonstrated enhanced SCFA levels and improved learning behaviors, linking AXOS to neurodevelopmental benefits.

Human Studies

Walton et al. (2012) conducted a randomized, crossover human trial where arabinoxylan supplementation significantly increased bifidobacteria populations, elevated SCFA levels, and improved gastrointestinal comfort. While mental health parameters were not primary outcomes, participants reported improved well-being and reduced stress symptoms.

Comparative Studies

Compared to inulin and galacto-oligosaccharides, arabinoxylan offers unique antioxidant and immune-regulatory properties. This makes it particularly promising as a dietary intervention for long-term brain health (Broekaert et al., 2011).

Clinical Evidence and Human Trials

Table 1: Summary of Key Studies on Arabinoxylan, Gut Microbiota, and Mental Health

Immune Modulation

Chronic systemic inflammation is a key feature of depression and anxiety. Arabinoxylan reduces inflammatory markers such as IL-6 and TNF-α, thereby lowering neuroinflammation (Neyrinck et al., 2011).

Stress Response and HPA Axis

By improving microbial diversity and reducing systemic stress responses, arabinoxylan indirectly regulates cortisol levels via the HPA axis (Cryan et al., 2019). This stabilizes emotional responses and enhances stress resilience.

FUTURE PERSPECTIVES AND CHALLENGES

Need for Clinical Validation

Most evidence linking arabinoxylan to mental health benefits comes from preclinical and pilot studies. Larger, longer human trials are needed to establish causal effects.

Personalized Nutrition

Individual responses to prebiotics depend on baseline microbiota composition. Personalized dietary interventions may be more effective than generalized recommendations.

Dosage and Delivery Optimization

Further research is needed to determine optimal daily intake of arabinoxylan and whether whole grains or purified AXOS supplements are more effective.

Integration into Psychiatry

Arabinoxylan-based interventions could complement existing treatments for depression and anxiety, potentially reducing drug dependence. However, interdisciplinary collaboration is necessary to integrate such dietary strategies into clinical practice.

CONCLUSION

According to the reviewed research, arabinoxylan is a promising prebiotic that can alter the gut-brain axis to enhance mental health. Arabinoxylan targets several pathways linked to mental illnesses by boosting the creation of SCFA, improving the good bacteria in the stomach, controlling immunological responses, and promoting the synthesis of neurotransmitters. More thorough clinical research is needed to convert findings into useful dietary recommendations, even if existing animal and early human studies corroborate these advantages. In the context of a comprehensive nutritional psychiatry approach, meals or supplements high in arabinoxylan may offer a secure, affordable, and long-lasting means of promoting mental health.

Conflicts of interests: The authors declare no conflicts of interest.

Author contribution: All authors have contributed in the manuscript.

Author funding: Nill

REFERENCES

1. Broekaert, W. F., Courtin, C. M., Verbeke, K., Van de Wiele, T., Verstraete, W., & Delcour, J. A. (2011). Prebiotic and other health-related effects of cereal-derived arabinoxylans, arabinoxylan-oligosaccharides, and xylooligosaccharides. Critical
2. Reviews in Food Science and Nutrition, 51(2), 178–194. https://doi.org/10.1080/10408390903044768
3. Carabotti, M., Scirocco, A., Maselli, M. A., & Severi, C. (2015). The gut–brain axis: Interactions between enteric microbiota, central and enteric nervous systems. Annals of Gastroenterology, 28(2), 203–209.
4. Courtin, C. M., & Delcour, J. A. (2002). Arabinoxylans and endoxylanases in wheat flour
5. bread-making. Journal of Cereal Science, 35(3), 225–243. https://doi.org/10.1006/jcrs.2001.0433
6. Cryan, J. F., O’Riordan, K. J., Cowan, C. S. M., Sandhu, K. V., Bastiaanssen, T. F. S.,
7. Boehme, M., ... & Dinan, T. G. (2019). The microbiota–gut–brain axis. Physiological Reviews, 99(4), 1877–2013. https://doi.org/10.1152/physrev.00018.2018
8. Dalile, B., Van Oudenhove, L., Vervliet, B., & Verbeke, K. (2019). The role of short-chain fatty acids in microbiota–gut–brain communication. Nature Reviews Gastroenterology & Hepatology, 16(8), 461–478. https://doi.org/10.1038/s41575-019-0157-3
9. Delgado, P. L., Moreno, F. A., & Gelenberg, A. J. (2021). Microbiota and mental health: Implications for depression and anxiety. Current Psychiatry Reports, 23(8), 46. https://doi.org/10.1007/s11920-021-01267-8
10. Foster, J. A., & McVey Neufeld, K. A. (2013). Gut–brain axis: How the microbiome influences anxiety and depression. Trends in Neurosciences, 36(5), 305–312. https://doi.org/10.1016/j.tins.2013.01.005
11. Gibson, G. R., Hutkins, R., Sanders, M. E., Prescott, S. L., Reimer, R. A., Salminen, S. J.,
12. ... & Reid, G. (2017). The ISAPP consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology, 14(8), 491–502. https://doi.org/10.1038/nrgastro.2017.75

13. Izydorczyk, M. S., & Biliaderis, C. G. (1995). Cereal arabinoxylans: Advances in structure and physicochemical properties. Carbohydrate Polymers, 28(1), 33–48. https://doi.org/10.1016/0144-8617(95)00077-1
14. Jiang, H., Ling, Z., Zhang, Y., Mao, H., Ma, Z., Yin, Y., ... & Ruan, B. (2015). Altered fecal microbiota composition in patients with major depressive disorder. Brain, Behavior, and Immunity, 48, 186–194. https://doi.org/10.1016/j.bbi.2015.03.016
15. Liu, Y., et al. (2020). Prebiotic effects of arabinoxylan oligosaccharides on gut microbiota and anxiety-like behavior in mice. Frontiers in Microbiology, 11, 561983. https://doi.org/10.3389/fmicb.2020.561983
16. Neyrinck, A. M., Van Hee, V. F., Piront, N., De Backer, F., Toussaint, O., Cani, P. D., & Delzenne, N. M. (2011). Wheat-derived AXOS: A prebiotic with impact on metabolic syndrome parameters and gut microbiota in obese mice. Molecular Nutrition & Food Research, 55(2), 295–304. https://doi.org/10.1002/mnfr.201000387
17. Strandwitz, P. (2018). Neurotransmitter modulation by the gut microbiota. Brain Research, 1693(Pt B), 128–133. https://doi.org/10.1016/j.brainres.2018.03.015
18. Walton, G. E., Lu, C., Trogh, I., Arnaut, F., & Gibson, G. R. (2012). A randomised crossover study investigating the prebiotic effects of wheat arabinoxylan on the human
19. gut microbiota. British Journal of Nutrition, 107(4), 608–618. https://doi.org/10.1017/S0007114511003459
20. Berding, K., Vlckova, K., Marx, W., Schellekens, H., Stanton, C., Clarke, G., Jacka, F., Dinan, T. G., & Cryan, J. F. (2021). Diet and the Microbiota-Gut-Brain Axis: Sowing the Seeds of Good Mental Health. Advances in nutrition (Bethesda, Md.), 12(4), 1239–1285. https://doi.org/10.1093/advances/nmaa181
21. Fereshteh Ansari, et al. (2023), The role of probiotics and prebiotics in modulating of the gut-brain axis; Front. Nutr., 26 July 2023 Sec. Nutrition, Psychology and Brain Health Volume 10 - 2023 | https://doi.org/10.3389/fnut.2023.1173660
22. Appleton J. The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health.
23. Integr Med (Encinitas). 2018 Aug;17(4):28-32. PMID: 31043907; PMCID: PMC6469458.
24. Marcel van de Wouw, Harriët Schellekens, Timothy G Dinan, John F Cryan, Microbiota-Gut-Brain Axis: Modulator of Host Metabolism and Appetite, The Journal of Nutrition, Volume 147, Issue 5, 2017, Pages 727-745, ISSN 0022-3166, https://doi.org/10.3945/jn.116.240481.
25. Rajanala K, Kumar N, Chamallamudi MR. Modulation of Gut-Brain Axis by Probiotics: A Promising Anti-depressant Approach. Curr Neuropharmacol. 2021;19(7):990-1006. doi: 10.2174/1570159X19666201215142520. PMID: 33327916; PMCID: PMC8686316.