The above text explains some physiological and pathological characteristics of MDD from the perspective of microbial metabolites (short-chain fatty acids, bile acids, amino acids, tryptophan derivatives, etc.) signaling pathways and functions.(Click to view)
This article will continue to elaborate on reconstructing the health status of depression patients from multiple aspects, such as nutritional supplementation, daily diet, exercise, sleep, etc.
It is well known that Lactobacillus and Bifidobacterium are the most widely used genera to inhibit harmful bacteria (i.e., excessive growth of Escherichia coli or opportunistic infections of Citrobacter) and enhance intestinal epithelial cells in gastrointestinal diseases.
Some studies have reviewed 'improving mental probiotics' specifically used to neutralize anxiety and depression symptoms: Lactobacillus fermentum NS8 and NS9, Lactobacillus casei Shirota, Lactobacillus gasseri OLL2809, Lactobacillus rhamnosus JB-1, Lactobacillus helveticus Rosell-52, Lactobacillus acidophilus W37, Lactobacillus plantarum W63, Lactococcus lactis W19 and W58, Bifidobacterium longum Rosell-175, Bifidobacterium longum NCC3001, Bifidobacterium longum 1714, Bifidobacterium bifidum W23, Bifidobacterium lactis W52, Lactobacillus plantarum 299v.
According to the International Scientific Association for Probiotics and Prebiotics (ISAPP), prebiotics are substrates selectively utilized by host microorganisms that can influence the growth and/or activity of these microorganisms in the digestive system while providing health benefits. Generally, prebiotics are indigestible carbohydrates (such as oligosaccharides, galacto-oligosaccharides, inulin, etc.).
A recent systematic review and meta-analysis indicated that, in contrast to probiotics, the use of prebiotics alone showed no significant difference in depression or anxiety symptoms compared to placebo. However, this fact does not mean that prebiotics are completely useless for MDD.
The mechanisms by which prebiotics work are as follows:
(1) Enhancing SCFAs in the gut;
(2) Reducing plasma cortisol;
(3) Increasing the activity of serotonin in the prefrontal cortex while reducing the activity of the amygdala in the brain stress circuit.
Short-chain fatty acids and derivatives
Oral administration of SCFAs has been shown to be a potential means of alleviating stress-related issues. In mouse models, a mixture of acetate, propionate, and butyrate can promote anti-anxiety and anti-depressive effects and improve corticosterone levels. One study indicated that changes in SCFAs levels in fecal samples from depressed patients were positively correlated with acetate levels and negatively correlated with butyrate and propionate levels. Therefore, short-chain fatty acids as nutrients seem to be significant in influencing depressive symptoms.
Increasing evidence suggests that the Mediterranean diet, rich in plant-based components (fruits, vegetables, legumes, olive oil, etc.), dietary fiber, and omega-3 polyunsaturated fatty acids, can establish a diverse microbiome and produce sufficient microbial metabolites. A large amount of bioactive compounds (polyphenols, carotenoids, phytosterols, etc.) in food has health benefits for the gut barrier and gut microbiome.
Studies have shown that exercise can enrich the diversity of the microbiome, thereby improving the endocrine function of the microbiome. Beneficial bacteria that produce SCFAs increase with exercise, and the MGB axis is also regulated.
Currently, known studies indicate that the high prevalence of insomnia and major depressive disorder is associated with circadian rhythms, immune function, and nutritional metabolism. In other words, the gut microbiome affects circadian rhythms, thereby influencing the host's metabolic homeostasis.
References:
Miguel A. Ortega.etc.Gut Microbiota Metabolites in Major Depressive Disorder—Deep Insights into Their Pathophysiological Role and Potential Translational Applications.[J]Metabolites:2022,12(1).
(The article is excerpted from popular science literature and does not provide any medical guidance.)
Some images and texts are sourced from the internet; if there is any infringement, please inform us for deletion.
