Influence of diets on the composition of intestinal microflora and on immune processes in the human

Diets, via the formation of a dominant microbial core, influence metabolic processes in the body, which determine changes in the individual's immune response. The work studies the influence of the main dietary regimes (vegan and vegetarian, ketogenic, gluten-free, Mediterranean diets, low FODMAP diet, Western diet) on the diversity and composition of the intestinal microflora. Vegans and vegetarians have a greater diversity of species from the Bacteroidetes group, an increase in the number of lactic acid bacteria such as Ruminococcus, E. rectale and Roseburia, and a decrease in the number of Clostridium and Enterococcus. This type of nutrition helps to enhance the protective properties of the intestines by increasing the number of bacteria that activate immune mechanisms. The ketogenic diet increases the number of Bacteroides and Akkermansia muciniphila, with a decrease in the number of Proteobacteria, Bifidobacteria, E. rectale, Dialister. As a result, the ketogenic diet alters the balance of pro- and anti-inflammatory mechanisms in the gut. A gluten-free diet causes a decrease in Bifidobacterium, Lactobacillus, Clostridium lituseburense, Faecalibacterium prausnitzii, Veillonellacea, Ruminicoccus bromii, Roseburia and an increase in the proportion of Enterobacteriacea (including Escherichia coli), Victivallaceae, Clostridiaceae and Coriobacteriaceae. This type of diet promotes the overgrowth of opportunistic microorganisms and weakens the host's defenses against infections and chronic inflammation. A diet low in short-chain carbohydrates (FODMAP) can lead to a decrease in the number of bifidobacteria, propionibacteria, F. prausnitzii, Akkermansia, Ruminococcus and an increase in the population of Clostridiaceae (Peptostreptococcus spp.) and, as a result, reduces the activity of immune mechanisms. The Western type of diet leads to a decrease in Bifidobacteria, Roseburia, Eubacterium, Ruminococcus, Lactobacillus, Prevotella and an increase in the number of Enterobacteria, Alistipes, Bacteroides. The Western type of diet, due to changes in the composition of normal microflora, increases the tendency towards obesity and weakening of protective properties. The Mediterranean diet leads to an increase in the concentration of F. prausnitzii, Bifidobacterium, Lactobacillus, Ruminococcus, Bacteroides and a decrease in the number of Clostridium, E. coli. This type of nutrition leads to a decrease in the number of opportunistic microorganisms and to the activation of immune mechanisms.