How diet shapes gut microbiota and affects brain function

Study: Feeding gut microbes to feed the brain: unraveling the diet-microbiota-gut-brain axis. Image credits: Ellen Eryomenko / Shutterstock.com

The increase in brain disorders is linked to poor nutrition, while healthy eating supports brain health. This review highlights the gut-brain axis, where diet influences brain function via the gut microbiota, and discusses its potential for the treatment of neuropsychiatric disorders.

A recent one Nature metabolism study discusses the diet-microbiota-gut-brain axis, which describes the role of both diet and gut microbiota composition on cognitive and emotional health.

Diet and the gut microbiota

Diets rich in carbohydrates increase significantly Bifidobacterium levels in the gut microbiome, while leading to lower levels Bacteroides levels. Undigested carbohydrates in prebiotics promote the growth of a healthy gut microbiota, benefiting the gastrointestinal (GI) tract.

Protein is the main source of amino acids, which are essential for brain health. Consuming plant-based protein increases levels of short-chain fatty acids (SCFA) and branched-chain amino acids (BCAA), both of which promote overall health. In comparison, long-term consumption of animal proteins can negatively impact the intestinal microbiota.

Increased consumption of saturated fats has been associated with cognitive impairment, while a reverse effect has been observed with the intake of unsaturated fatty acids. The amount and saturation of fat determines the exact effects on the intestinal microbiota.

Minerals, vitamins and trace elements are necessary for the survival and growth of various intestinal bacteria. Micronutrient deficiencies can thus lead to poor cognitive performance and emotional disturbances.

Previous studies have also shown the link between mood disorders and the consumption of ultra-processed foods (UPF), with the gut microbiome playing a key role in this relationship.

The gut-brain axis and neuropsychiatric disorders

The gut microbiota regulates anorexia nervosa (AN), which causes underweight due to compensatory behavior and/or chronic food restriction. The risk of schizophrenia may also be partially mediated by the gut microbiota due to inflammation caused by maternal malnutrition or postnatal nutrition due to over- or undernutrition.

The ketogenic diet increases the abundance of certain genera, such as Bifidobacterium And Akkermansia. Increasing ketone production through this nutritional approach inhibits apoptosis and reduces oxidative stress, which has been therapeutically effective in treating certain forms of epilepsy.

Dietary patterns, especially those involving increased consumption of high-fat dairy products, meat, butter, eggs and refined sugar, are associated with an increased risk of dementia or Alzheimer’s disease (AD).

Children with attention deficit hyperactivity disorder (ADHD) show lower serum concentrations of chromium, magnesium and zinc. ADHD has also been linked to increased abundance Eggerthella And Faecalibacterium.

Intestinal metabolites and their therapeutic potential

Several molecular pathways are involved in the bidirectional communication of the diet-microbiota-gut-brain axis, which coordinates cognition and emotion in healthy and disease states. Bacterial metabolites involved in digestion similarly influence communication between the gut microbiota and the brain.

SCFAs, such as propionate, acetate, and butyrate, produced by microbial fermentation of host-indigestible dietary fiber or microbial protein degradation, are associated with blood pressure regulation, GI function, neuroimmune function, and circadian rhythm regulation. Several studies have shown that the changes in fecal SCFA levels are associated with obesity, Parkinson’s disease (PD), ASD, and chronic psychosocial stress, demonstrating the robust role of SCFAs in microbiota-gut-brain axis-related disorders .

A reduction in SCFA-producing bacteria in the intestines increases the risk of Parkinson’s. This has led researchers to investigate the efficacy of propionate treatment, which has been shown to increase the survival rate of dopaminergic cells in a PD mouse model.

Taurine is another microbial metabolite involved in host digestion. In addition to its role in digestive processes, taurine is associated with anticonvulsant, neuroprotective and cognitive enhancing properties through its activity as an agonist of glycine, gamma-aminobutyric acid type A (GABAA) and gamma-aminobutyric acid type B (GABAB). ) receptors in the brain. Taurine supplementation has potential therapeutic value in epilepsy, AD, PD, anxiety and depression.

Important gut-associated microbial taxa, such as Bifidobacterium, LactobacillusAnd Bacteroidetesexpress bile salt hydrolase enzymes that deconjugate bile acids from taurine and glycine. Changes in the composition of the gut microbiota due to an unbalanced diet can induce neuroinflammation and reduce synaptic plasticity due to reduced TGR5 signaling and changes in bile acid synthesis.

Commensal bacterial metabolites such as choline, bacteriocins, neuromodulators, bile acids, and SCFAs function as signaling molecules and can modulate microbe-host interactions. These metabolites influence neural signaling and communicate with the brain.

Future perspective

Additional research is needed to evaluate how chronic food intake affects the microbiota-gut-brain axis. Longitudinal and multimodal study designs can be used to understand the role of the diet-microbiota-gut-brain axis in the pathogenesis of neuropsychiatric disorders and/or in the severity of symptoms. Additionally, randomized controlled trials can be conducted to determine whether diet-induced changes in the gut microbiota affect clinical populations.

The #diet #microbiota The gut-brain axis represents an uncharted frontier for diagnostics and therapies for brain health across the lifespan. #Aging New from @jfcryan @NatMetabolisme Feeding the microbes #microbiota https://t.co/c1ZjiNBHgf

— Daniel J Drucker (@DanielJDrucker) August 22, 2024