The brain influences nearly every major physiological process in the body. Of no less significance is the body’s gastrointestinal tract, also sometimes called the “second brain”. Healthy “cross-talk” between these two systems is crucial for overall mind and body wellness with fibers offering a simple and effective way of maintaining healthy gut-brain communication. Therefore, many experts recommend adding sufficient amounts of dietary fiber to help support cognition, mental and brain well-being, gut balance, and better overall health.
In the body, no symbiotic relationship is of greater significance than the one residing in the intestinal microbiome. Within this dynamic biological ecosystem, the bacterial microbiota interacts with, and utilizes, an assortment of dietary fibers — including prebiotics. These synergistic microbe-substrate interactions result in the formation of active metabolites — signaling molecules that drive local and systemic feedback in the body.
Such an intricate process of regulation requires a complex, interconnected system of “bionodes” — the microbiota-gut-brain axis. This dynamic, multi-directional network consists of key cellular and molecular interactions that help maintain homeostasis in the body — ultimately promoting optimal digestion, metabolism, immunity, cognition, and brain health.
Over the past decade, the microbiota-gut-brain axis has garnered much public and academic interest. Perhaps of equal intrigue is the search for interventional strategies able to positively modulate this key “bioaxis”.
As more clinical and scientific evidence emerges, it is becoming undeniably clear that dietary fibers, prebiotics, and the microbiota-gut-brain axis all play a significant role in brain wellness throughout life. However, despite this discovery, the exact mechanisms by which each supports cognitive function and brain health are only beginning to be fully understood.
This deep dive will first cover general information about dietary fiber and prebiotics — along with how the enteric microbiota utilize these unique carbohydrates. Next, the microbiota-gut-brain axis, its components, as well as known direct and indirect mechanisms will be covered in detail. Finally, the present body of applicable clinical and scientific literature will be discussed — specifically examining the impact of dietary fiber/prebiotics on cognition, anxiety, depression, and brain health.
The official definition of what constitutes a dietary fiber has changed over the years. Today, dietary fibers are described as complex, whole carbohydrates that have three key characteristics:
Certain sub-types have additional attributes, but the above mentioned are consistent across all dietary fibers [R, R].
Overall dietary fiber classification is complex — however, generally speaking, two main categories exist — water soluble and insoluble. Both fiber types are found in a wide range of fruits, vegetables, grains, and legumes (beans, nuts, peas, and lentils) in different respective amounts [R, R, R].
Supplemental or added/functional fiber is included under the umbrella of dietary fiber and contributes to total dietary fiber intake. However, natural dietary fiber is still considered a healthier option due to the additional macro- and micronutrients found in foods with higher fiber content [R, R].
The recommended daily intake for total dietary fiber varies based on age and gender, with 15 grams per 1,000 calories being considered optimal. Simplifying this equates to approximately 20 to 25 grams for adult women and 30 to 40 grams for adult men per day [R, R].
Soluble dietary fiber undergoes moderate metabolism in the gastrointestinal (GI) tract, forming a suspension- or gel-like solution. This characteristic slows digestion, prolongs nutrient absorption, provides a more pronounced sense of fullness or satiety, and can help to prevent or relieve diarrhea [R, R, R].
Insoluble dietary fiber passes through the GI tract mostly undigested. With the ability to absorb water, it acts as a natural bulking and stool softening agent — preventing constipation and promoting intestinal regularity [R, R].
The classification of dietary fibers has changed over time and is a subject of continued debate in the scientific community. It has been proposed that simply dividing dietary fibers into soluble or insoluble is sub-optimal. Instead, experts argue that dietary fibers should also be categorized based on characteristics such as viscosity and fermentability [R, R].
This controversy has led to some disagreement on how dietary fibers should be categorized. Although various methods have been proposed, and utilized, no concise classification system has yet to be agreed upon in the scientific literature.
Regardless of how different dietary fibers are grouped, the consensus among experts is to maintain a balanced diet that includes a variety of dietary fibers. They also contend that consuming a diversity of dietary fibers, with complimentary and/or synergistic mechanisms, provides the most overall health benefits [R].
Luckily for consumers, many foods high in dietary fiber contain more than one type of fiber, and most have up to 3 or 4 [R].
As was the case with general dietary fiber categorization, the definition of what constitutes a prebiotic has changed over the years [R].
The verbiage was modified in 2017 to include soluble dietary fibers that were previously excluded (pectins and gums). Prebiotics are now defined as, “substrates that are selectively utilized by host microorganisms conferring a health benefit” [R].
All prebiotics are considered soluble dietary fibers, however, not all soluble dietary fibers are classified as prebiotics.
The most common exception is psyllium or psyllium husks — a bulking agent found in supplemental fiber products such as Metamucil [R, R].
In addition to psyllium, there is another non-prebiotic soluble dietary fiber, gellan gum or E418. This gum undergoes very low levels of fermentation and is used as a food additive or drug delivery medium [R, R].
Approximately 95% of the body’s microorganisms are located in the colon. Collectively known as the gut microbiota, this assembly of diverse microbes is responsible for maintaining the “functional output” of the intestinal microbiome — an all encompassing term used to describe a biological ecosystem and the interactions that take place within it. In the case of the gastrointestinal (GI) microbiome, it contains bacteria, fungi, viruses, and archaea — along with their genetic material and biochemical mediators [R, R, R, R, R].
By far the most important component of the gut microbiota is the assortment of host bacteria residing in the intestines. Each species is uniquely impacted by different combinations of intrinsic and extrinsic factors including [R, R, R, R]:
Soluble and insoluble dietary fibers both interact positively with the gut microbiota, albeit in different ways.
Soluble dietary fibers, specifically prebiotics, are used directly by the gut microbiota, serving as “food” for the healthy bacteria of the gut through a process called fermentation. The byproducts of this biochemical process then go on to stimulate colony expansion, promote flora homeostasis, and serve as biochemical messengers throughout the body [R, R, R, R].
Insoluble dietary fibers (i.e. cellulose and lignin) play a more indirect role in the intestines by creating a more hospitable environment for the local microbiota, all while promoting overall microbiome balance in the gut [R].
Although beyond the scope of this article, the gut microbiota also utilizes a host of other macro- and micronutrients including [R, R, R, R, R]:
The recognized importance of dietary fiber and prebiotics in general health and wellness has increased dramatically over the last decade.
To reiterate, dietary fibers/prebiotics simply act as substrates for the bacterial microbiota of the gut — supporting a robust, diverse microbial ecosystem [R, R, R, R, R, R, R, R].
Without sufficient dietary fiber/prebiotic intake, the intestinal microbiome can enter a state of dysbiosis, which simply means microbiota imbalance. If left unchecked, this can contribute to the development of a collection of pathologies including neurological and metabolic diseases, gastrointestinal disorders, obesity, and even colorectal cancer [R, R, R].
The connection between microbiota abnormalities, impaired cognition, and diminished brain health is primarily due to the dysfunction of an integral, homeostatic network in the body known as the microbiota-gut-brain (MGB) axis.
In recent years, the communal nomenclature has been expanded to include the microbiota as a separate component of the gut-brain axis, emphasizing the importance of the intestines’ healthy bacteria in this complex biological system. Therefore, the gut-brain axis is now referred to as the microbiota-gut-brain (MGB) or brain-gut-microbiota (BGM) axis.
The MGB can be most accurately described as a multidirectional network consisting of three cyclical oriented “bionodes” [R, R, R, R, R]:
The MGB axis involves a diverse range of cell types such as neurons (afferent vagal neurons), glia (microglia and astrocytes), enterocytes, enteroendocrine cells, and non-CNS immune cells [R, R, R, R].
In addition, a host of different biochemical messengers mediate cell to cell interactions and signaling throughout the network including [R, R, R, R, R, R, R, R, R, R, R]:
Individual nodes of the MGB axis, including each component’s respective cell types and signaling molecules, create a system where dynamic, continuous communication and feedback takes place — both within isolated nodes and between nodes [R, R].
The gut microbiota, via the MGB axis, influences many important biochemical, biological, and physiological processes in the body — ultimately driving optimal mind and body wellness.
A healthy MGB axis supports better gut motility and integrity, improved immune system function, and proper metabolism [R, R, R, R, R, R, R, R].
In respect to the brain, a properly functioning MGB axis helps to boost cognition, improve mood (limit anxiety and depression), and support brain health [R, R, R, R, R, R, R, R].
Exactly how the MGB axis impacts the brain is not fully understood, however, it is clear that communication within the MGB axis occurs by two main routes. First is directly along the vagus nerve (“one-step”) or via the ENS AND vagus nerve (“two-step”). The second route of transmission is indirectly through the systemic circulation [R, R].
The vagus nerve represents a collection of neuronal projections (axons) essential for normal ANS and peripheral nervous system (PNS) functionality. This integral family of nerves contains a fiber ratio of approximately 10 to 20% efferent (outgoing) to 80 to 90% afferent (incoming) [R, R, R, R.
Vagal nerves innervate both the intestines and ENS. This distinct organization is what allows for MGB axis bidirectional communication between the brain and GI tract using either a one- or two-step process respectively [R, R, R, R].
Each single or multi-step direct signaling pathway is mediated by microbiota independent and dependent mechanisms.
Both the vagus nerve and the ENS have the ability to sense the localized environment of the gut and relay feedback to the brain [R, R, R, R].
As discussed previously, microbiota-dietary fiber/prebiotic interactions in the intestines result in the formation of important active metabolites. The vagus nerve and the ENS are both able to then translate input from these molecules and relay various information to the brain. [R, R, R, R, R, R, R, R, R].
Interestingly, bacterial microbiota of the gut also have innate ability to synthesize and respond to several different types of neurotransmitters, independent of host diet [R, R, R, R, R, R].
This second major route of MGB axis communication involves active metabolites accessing the bloodstream by two distinct routes — migration through the gastrointestinal lining or entrance via hepatic veins following metabolic processing in the liver [R].
After accessing the systemic circulation, these molecules go on to target a variety of locations throughout the body. In addition to the brain and liver, they can also affect the heart, kidneys, and bone marrow [R, R].
Despite knowledge gaps existing in the understanding of blood driven MGB axis signaling, one thing is clear — most of these routes of communication exhibit some degree of “cross-talk” with one another [R, R, R, R, R, R, R, R, R].
MGB axis metabolic pathways are impacted by a host of internal and external factors, ultimately resulting in the release of microbiota-created active metabolites. These molecules, which can be both “positive” (i.e. SCFAs) or “negative” (i.e. trimethylamine-n-oxide or TMAO), are then able to directly or indirectly influence multiple neurologic, immune, and endocrine signaling cascades [R, R, R, R, R, R, R, R, R, R, R].
For instance, SCFAs can directly enter the systemic circulation to act on distal endocrine or non-endocrine cells in the brain. Alternatively, indirect communication involves SCFAs exerting effects locally in the gut — stimulating the release of hormones such as GLP-1 and PYY from enteroendocrine cells. These neuropeptides are also able to enter the systemic circulation and carry out a host of feedback related functions along the MGB axis [R].
Serotonin is involved in the regulation of mood, sleep, learning, and memory. Abnormalities in serotonergic signaling have also been linked to mood related disorders such as anxiety and depression [R, R, R, R].
Although typically thought of as a CNS exclusive neurotransmitter, serotonin also serves as a hormone in the PNS and gut. It can enter the bloodstream, be taken up by platelets, and transported throughout the body to participate in various physiological processes such as [R, R, R, R]:
In the intestines, serotonin helps regulate appetite, satiety, digestion, metabolism, motility, and nutrient absorption [R, R, R, R].
The cell type responsible for the release of serotonin in the gastrointestinal tract are enterochromaffin cells. This subclass of enteroendocrine cells are found in the gut lining, and store up to 90% of the body’s serotonin — releasing it in response to electrophysiological or biochemical stimuli. It should be noted that there is some conflicting data regarding this phenomenon. Therefore, additional research needs to be conducted to reproduce this scientific finding [R, R, R, R].
Reemphasizing the crosstalk between indirect mechanisms of the MGB axis, other types of intestinal enteroendocrine cells also secrete hormones, including GLP-1 and PYY, in response to microbiota released active metabolites (SCFAs) [R, R, R].
Serotonin produced and released in the intestines does not influence levels in the brain — it is rapidly metabolized in the systemic circulation and can not pass through the blood brain barrier (BBB) [R, R, R, R].
On the other hand, serotonin’s precursor, tryptophan, is able to reach the brain and readily cross the BBB, despite the majority of it being oxidized/inactivated in the liver through the kynurenine pathway. Tryptophan is not a direct precursor to serotonin, it must first be converted to 5-hydroxytryptophan (5-HTP), but is still capable of raising serotonin levels in the brain [R].
The hypothalamic-pituitary-adrenal (HPA) axis is a neuroendocrine signaling mechanism primarily involved in cortisol release and the body’s flight or flight response. It is activated by a wide range of biological, physiological, and biochemical stimuli resulting from exposure to various physical and psychological stressors [R].
Two important mediators of this stress response are the gut microbiota and the immune system. Generally speaking, this unique branch of the MGB axis is designed to protect the brain and body from harmful stressors, allowing for rapid and efficient communication between the brain and the rest of the body [R].
However, under pathophysiological conditions the immune system can be overstimulated either directly by cytokines (small inflammatory molecules), or indirectly through negatively-associated, microbiota-created active metabolites (i.e. trimethylamine N-oxide/TMAO and secondary bile acids such as deoxycholic acid) during states of dysbiosis or microbial translocation (movement of microbes into the bloodstream) [R, R].
Acute and chronic stress is one physiological state that has been shown to alter gut microbiota composition. At times dysbiosis can develop, which under the right conditions, can lead to the production of negative feedback along the MGB axis. The end result of this dysfunction is deleterious amounts of cortisol being released through the HPA axis (from the adrenal gland). Ultimately, this dysregulation can result in the development of metabolic, auto-immune, and neurodegenerative disorders [R, R].
The MGB and HPA axes also play a role in mood regulation and motivation, as well as cognition, affecting processes like memory and attention [R].
Therefore, it is unsurprising that MGB and HPA axis dysregulation is thought to play a role in the development of psychiatric disorders such as anxiety and depression [R, R].
The clinical literature contains a collection of broad dietary fiber studies, as well as prebiotic specific ones. The two terms (dietary fibers and prebiotics) are often used synonymously, however researchers often conduct studies on one or the other — therefore, we’ll discuss each individually, then summarize the overall findings.
A number of short- and long-term clinical studies, across a variety of age ranges (majority were in adults over the age of 60), have investigated the impact of higher dietary fiber intake on global cognitive performance as well as specific aspects of cognition including: attention, memory, learning, executive function, and mood [R].
The results from these studies have been somewhat mixed, however the majority observed a positive correlation between increased dietary fiber intake and improvement in at least one component of cognitive function.
In a study published 2022, researchers analyzed the impact of dietary and total (dietary and supplements) fiber intake on acute cognitive function in a cohort of individuals over the age of 60. After adjusting for confounders, they observed better overall cognition — combined measurements of learning, executive function, attention, and memory — in participants with higher total fiber intake. When looking at individual domains of cognition, they found a trending, but not significant, difference in either the dietary or total fiber groups [R].
A second independent group of researchers in the same year analyzed a similar data set and found that those with higher dietary fiber intake scored better on acute cognitive tests measuring sustained attention, processing speed, and working memory [R].
Additional long-term studies have demonstrated that higher fiber intake is associated with lower rates of cognitive decline and a higher incidence of “successful aging” as defined by, “absence of disability, depressive symptoms, cognitive impairment, respiratory symptoms, and chronic diseases” [R, R].
With respect to prebiotics, and their ability to positively impact the brain, a smaller body of clinical literature exists when compared to overall dietary fiber. The majority of studies investigated the long-term effects of prebiotic supplementation on various cognitive domains across a variety of age ranges [R, R, R].
A recent 12 week study in subjects over the age of 60 found that a combination prebiotic containing inulin and fructo-oligosaccharides (FOS) improved overall cognitive function and spatial working memory, but not executive function or other measurements of memory [R].
Another recent 12 week study in men and women between the ages of 50 and 80, observed improvements in overall cognitive function, as well as measurements of attention, executive function, and mind flexibility in subjects given a prebiotic-probiotic supplement (inulin and Bifidobacterium animalis subsp. lactis GCL2505) [R].
A third month-long study in 18 to 40 year old females discovered that a polydextrose (PDX) prebiotic improved cognitive flexibility and sustained attention [R].
Finally, an acute 2015 study found that subjects taking inulin performed better on tests of episodic memory (“free recall and recognition”) and subjective happiness, but found no improvement with respect to anxiety, psychomotor activity, or attention [R].
Despite the positive outcomes of these small scale clinical studies, a 2020 meta-analysis found no significant improvement following prebiotic intake for global cognition or any specific cognitive domain [R].
A more recent 2024 publication, analyzed clinical studies containing a probiotic, prebiotic, or symbiotic intervention ranging from 4 weeks to 6 months. The authors concluded that all three strategies had a positive impact on cognition in i) healthy elderly subjects, ii) subjects with mild cognitive impairment over the age of 60, and iii) subjects diagnosed with Alzheimer’s over the age of 60 [R].
However, a significant caveat to this study is that it did not contain a meta-analysis of pooled data from the included clinical trials. Therefore, the analysis provided no additional supporting evidence regarding the positive impact of prebiotics on cognition, and was simply a summary of published studies [R].
Collectively, a sufficient amount of evidence exists demonstrating the brain-related benefits of dietary fiber — with the most common being improved attention and memory.
Specific prebiotics may help with certain areas of cognition, however more clinical research needs to be conducted before any definitive conclusions can be drawn.
First, it is important to keep in mind that mental health can mean different things to different people. In addition, an official definition is not widely agreed upon — and what constitutes good mental health has changed over the years [R, R, R, R, R].
The most comprehensive description of mental health is put forth by the American Psychological Association. They define it as, “a state of mind characterized by emotional well-being, good behavioral adjustment, relative freedom from anxiety and disabling symptoms, and a capacity to establish constructive relationships and cope with the ordinary demands and stresses of life” [R, R, R].
A second commonly quoted definition of mental health is from The World Health Organization (WHO). They define it as, “A state of well-being in which the individual realizes his or her own abilities, can cope with the normal stresses of life, can work productively and fruitfully and is able to contribute to his or her community” [R, R, R].
Although neither definition includes the word mood, they do mention associated words including emotion, anxiety, stress management, and well-being. Both definitions also do not contain the word depression. Even though this is the case, it could be argued that those at a lower risk or incidence of developing depression would also exhibit improved mood and mental health.
The MGB axis not only influences cognitive function, it also affects anxiety and depression — two factors that play a significant role in mood and mental health [R, R, R, R, R].
Again, the clinical literature contains studies investigating both total dietary fiber intake or prebiotic consumption. Therefore, like with cognition, we’ll discuss the impact of each on anxiety and depression.
A 2024 meta-analysis found a small, but significant improvement for anxiety outcomes in subjects with higher total dietary fiber intake. They also discovered a small, but significant improvement for depression outcomes in those with higher total dietary fiber intake [R].
Interestingly, when looking at fiber interventional studies — the same meta-analysis revealed no significant improvement for anxiety or depression outcomes in individuals taking fiber supplements [R].
In a second recent meta-analysis, investigators discovered a dose-dependent reduction for the odds of developing depression in adults with a higher dietary fiber intake. Dietary fibers’ impact on anxiety was, “not included in the analysis, due to insufficient eligible studies” [R].
A third meta-analysis, looking specifically at the relationship between dietary fiber intake and the risk of developing depression. The authors concluded that higher dietary fiber intake was associated with a lower odds of individuals exhibiting clinical depression [R].
In a fourth published clinical study, higher dietary fiber intake was positively associated with better scores on a test assessing periodic perceived mental health. The test monitored levels of anxiety and depression in women, aged 55 to 69, over a 17 year period [R].
The results from these four publications demonstrate that higher dietary fiber intake is associated with a lower incidence of anxiety and depression — two important factors in mental health. However, they do not delineate whether the results are due to non-prebiotic or prebiotic dietary fibers, nor do they show a positive correlation between fiber supplementation and a decreased risk for developing anxiety or depression.
Therefore, it is important to also look at interventional studies that focus on supplemental prebiotics. This additional due diligence sheds light on what specific fiber types are responsible for the significant impact that higher dietary fiber intake has on rates of anxiety and depression.
A limited number of studies have looked at the ability of prebiotics to improve anxiety and depression with mixed results. Study design wise, the literature contains a mix of diet and supplement based interventions.
A recently published 2023 study, found that subjects adhering to a prebiotic-rich diet (consuming at least 5 grams of quality prebiotics per day) had less total mood disturbances (TMDs) at 8 weeks. Researchers also tracked secondary outcomes, including anxiety, stress, sleep, wellbeing/depression, and fatigue. They observed a significant improvement in anxiety, stress, and sleep in the prebiotic diet group, but no difference in wellbeing/depression and fatigue, also at 8 weeks [R].
Upon follow-up at 20 weeks, subjects in the prebiotic diet group no longer displayed a lower number of TMDs. The study’s authors attributed this to there being no significant difference in total dietary prebiotic intake between the prebiotic diet and placebo groups. It was unclear as to why the investigators thought subjects in this specific group did not adhere to study protocols [R].
Several older studies investigated the impact of prebiotic supplements on mood or mood related parameters including anxiety, depression, and perceived stress.
The first study was an acute investigation of the effect of inulin on mood and anxiety. The authors found no significant difference for either in the inulin group [R].
A second interventional study administered two different prebiotics, Bimuno®-galactooligosaccharides (B-GOS) and fructooligosaccharides (FOS) to healthy subjects for 3 weeks. At the conclusion of the 21 days, only members of the B-GOS group had lower cortisol levels, and exhibited a significant improvement in mental well-being as measured by an increased response to positive stimuli and a decreased response to negative stimuli. The researchers found no other differences between groups for reaction time, attention, anxiety, or stress [R].
The third analysis was a 12 week study that looked at anxiety, depression, and perceived stress after polydextrose (PDX) intake. They also found no statistically significant difference between the PDX and placebo groups for any of the three mood related outcomes [R].
The MGB axis is not the only way that dietary fibers and prebiotics are thought to influence anxiety and depression. Inflammation is also thought to be a key mediator for the development of psychiatric disorders in general.
The main issue that surrounds this hypothesis is the chicken or the egg argument, with the jury still out as to which comes first. The answer to this question is likely both — chronic inflammation in the body and brain can lead to the development of psychiatric disorders and vice versa.
To complicate this discussion further is the fact that additional biological processes influence body and brain inflammation including the MGB axis itself, as well as neuroendocrine regulation, and metabolism [R].
Two common metrics of mental health status are general anxiety and depression. Therefore, strategies to limit or alleviate one or both of these factors is beneficial for mental health.
A relatively large amount of evidence exists that demonstrates the efficacy of dietary fiber and its impact on anxiety and depression. Although this is not a direct link to mood and mental health, the majority of analytical methods used to measure both of these parameters include anxiety and depression.
More studies need to be conducted to determine if specific or combinations of 2 or more prebiotics improve anxiety, depression, mood, or mental.
The main issue that surrounds this hypothesis is the chicken or the egg argument, with the jury still out as to which comes first. The answer to this question is likely both — chronic inflammation in the body and brain can lead to the development of psychiatric disorders and vice versa.
To complicate this discussion further is the fact that additional biological processes influence body and brain inflammation including the MGB axis itself, as well as neuroendocrine regulation, and metabolism [R].
Brain health is a very broad term that has two fairly distinct descriptions. The first defines brain health as a function of cognition. Although this viewpoint is not incorrect, it only provides one piece of the puzzle.
From a neuroscience perspective, brain health isn’t simply how well a brain functions — it is also a representation of the overall molecular, cellular, and structural integrity of the brain.
Someone can possess an otherwise healthy brain that does not function well, and vice versa — a person may exhibit good cognition, but their brain may not be considered healthy from a microscopic point of view.
Therefore, perhaps a more accurate description of brain health would be brain wellness. This more encompassing term, can then be separated into two distinct, but very much interdependent components, cognition AND brain health. Additional top-down “sub-divisions” of these two main components then allows for an interventional strategy that identifies and targets functional, structural, cellular, and molecular neural metrics of greatest significance.
In respect to cognition, specific functional areas of interest would include higher order brain functions such as attention and memory. When referring to brain health, important neurobiologic mechanisms like antioxidation and synaptogenesis would be reinforced.
Ideally, each identified component of optimal cognition and brain health would impact one or more of the above mentioned neural metrics.
For example, myelination — the formation of insulative myelin sheaths around neuronal projections, created by specialized glial cells called oligodendrocytes — is important for the structural, cellular, and molecular integrity of the brain, making it a prime target to help support optimal brain health.
Another important point is that anything that supports brain health will have an indirect, positive impact on specific elements of short- and long-term cognition. The reverse is also true — supporting cognition will have a lasting, positive impact on brain health. This cyclical “reinforcement loop” is what makes comprehensive brain support so powerful and effective.
This systematic intervention strategy is precisely how Nurelto® was formulated. It includes 31 micro-nutrients that target 27 areas of cognition and brain health in 7 categories. No product on the market can match the comprehensive brain support Nurelto® provides.
Shifting back to looking at the brain from a microscopic perspective, there is little direct evidence that dietary fiber or prebiotics improve its overall health [R].
One study in a 60 years of age and older, dementia-free population, analyzed a collection of macro- and micronutrients and their effect on the brain via magnetic resonance imaging (MRI) over a 2 year period. Researchers found a diet rich in fiber and antioxidants (vitamins C and E, β-carotene, and folate) had the most significant positive impact on total brain volume (TBV) and white matter damage [R].
In addition to MRI, a host of other imaging techniques can be used to analyze the structural integrity of the brain including [R, R]:
At a cellular level, individual neurons and glia can be studied using single– or multi-cell analysis, electrophysiology (cell electrical activity), and histology (cell morphology/form). However, these methods are very invasive, dangerous, and rarely done in humans in vivo. Instead, much of the published literature contains cellular, animal, or post-mortem human studies.
On the other hand, the molecular study of brain health can be done on human samples, making it much more practical and less invasive. These techniques include genomics, proteomics, and metabolomics — corresponding to the study of brain-related genes, proteins, and metabolites respectively.
As new techniques emerge for studying the cellular and molecular integrity of the brain, we will gain greater insight into what constitutes optimal brain health and healthy brain aging, as well as learn how to better prevent and treat neurological diseases [R].
Despite the lack of data demonstrating a direct link between dietary fiber, prebiotics and brain health, there is an expanding body of literature that establishes an indirect association via the MGB axis.
Scientific studies have shown that a healthy MGB axis supports many important biological and biochemical processes involved in overall brain health including [R]:
The primary mechanism by which the MGB axis affects brain health is through the actions of postbiotics called small chain fatty acids (SCFAs) such as butyrate, propionate, and acetate [R].
A more encompassing, yet still inclusive, name for brain health would be brain wellness. After separating the two terms, brain health can then be viewed at a structural, cellular, and molecular level.
The most compelling evidence linking brain health, dietary fiber, and prebiotics comes from non-clinical research involving the positive modulation and support of the MGB axis. The primary way in which the MGB exerts its effects on the brain is through probiotics called small chain fatty acids (SCFAs), which include butyrate, propionate, and acetate.
Although the clinical literature is lacking, there are a number of viable methods to analyze the structural integrity of the brain. There are also several techniques that are used to investigate the molecular make-up of the brain where specific brain-related genes, proteins, and metabolites are evaluated.
In the years to come, new techniques will allow for more clinical studies to be conducted looking specifically at the impact of dietary fibers and prebiotics on the structural, cellular, and molecular integrity of the brain.
