Ay have a different composition in those with depression vs. healthy controls [147,148]. There are multiple pathways by which microbiota may influence brain development, stress physiology, mood, cognition, and behavior. These include, but are not limited to, direct communication with the brain via the vagus nerve, immune-mediated pathways (for example, cytokine production), limitation of oxidative stress, enhancement of purchase AZD-8835 nutrient bioavailability and neurotransmitter precursors (for example, tryptophan), and proper maintenance of the gastrointestinal barrier (that is, preventing intestinal permeability and a subsequent cascade of low-grade inflammation) [149]. Although most of the research concerning intestinal microbiota and mental health rests upon rodent studies, a few human studies have provided preliminary evidence that orally administered probiotics or fermented foods may support good mental health [150-156]. The reader is referred to expert reviews for more detail [157,158]. The research concerning microbiota and mental health is highly attractive because it represents a potential link between dietary patterns and environmental considerations. For example, in an experimental study, the transplantation of fecal microbiota from high-fat-diet-fed donor mice into lean mice (raised on standard chow) resulted in altered neurologic function. Interestingly, there were changes in behavior suggestive of anxiety, increased stereotypical behavior, and decreased memory in leanmice upon fecal transfer [159]. Also, the idea that fermented foods may provide enhanced mental health benefit by both direct microbial influence within the intestinal tract and indirect mechanisms through transformation of food chemicals (for example, enhancing nutrient absorption) has been proposed [160]. The lessons learned over the last several decades concerning the hygiene hypothesis – that which suggests the global rise in allergic disease could be related to diminished opportunity for early life exposure to pathogenic microbe exposure via increased hygiene, antibiotics, smaller family sizes, and altered dietary patterns [161,162] suggest that its overarching theme may also extend to PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26080418 neurocognitive and mental health [163,164]. For example, it was recently reported that higher consumption of fermented foods is associated with lower rates of allergy in children [165], a finding that could be related to mental health as described above [160]. Although intestinal microbes are strongly influenced by dietary factors, they are also a product of environmental bacteria [166-168]. Remarkably, the level of green space and biodiversity of vegetation surrounding one’s residence has been linked with both diversity of select bacteria on the skin, and lower odds of an allergic IgE reaction to common allergens [169,170]. Keeping in mind that environmental biodiversity (for example, variety of plants and birds in a local setting) has been linked to psychological well-being [171-174], it may very well be the case that `access’ to microbial diversity may emerge as a matter of environmental justice.Grey space and the environmental pushThe preponderance of existing research would suggest that the tripod of healthy dietary habits, diversity of microbiota, and access to quality natural environments are in the best interest of positive mental health. The research also suggests that these are overlapping conversations. For example, closer residential proximity to urban green space and greate.
