Dietary Fatty Acids Sustain the Growth of the Human Gut Microbiota

Abstract

While a substantial amount of dietary fats escape absorption in the human small intestine and reach the colon, the ability of resident microbiota to utilize these dietary fats for growth has not been investigated in detail. In this study we used an multi-vessel simulator system of the human colon to reveal that human gut microbiota is able to utilize typically consumed dietary fatty acids to sustain growth. Gut microbiota adapted quickly to a macronutrient switch from a balanced Western diet type medium to its variant lacking carbohydrates and proteins. We defined specific genera that increased their abundance on the fats-only medium, including, , and several genera of class Gammaproteobacteria. In contrast, abundances of well-known glycan and protein degraders including, , and were reduced in such conditions. Predicted prevalences of microbial genes coding for fatty acid degradation enzymes and anaerobic respiratory reductases were significantly increased in the fats-only environment, whereas the abundance of glycan degradation genes was diminished. These changes also resulted in lower microbial production of short chain fatty acids and antioxidants. Our findings provide justification for the previously observed alterations in gut microbiota observed in human and animal studies of high-fat diets. Increased intake of fats in many developed countries raised awareness of potentially harmful and beneficial effects of high fat consumption on human health. Some dietary fats escape digestion in the small intestine and reach the colon where they can be metabolized by gut microbiota. We show that human gut microbes are able to maintain a complex community when supplied with dietary fatty acids as the only nutrient and carbon sources. Such fatty acid based growth leads to lower production of short chain fatty acids and antioxidants by community members, which might potentially have negative health consequences on the host.

Dietary Lipids Influence Bioaccessibility of Polyphenols from Black Carrots and Affect Microbial Diversity under Simulated Gastrointestinal Digestion

“…High plasma triglycerides concentrations may be a result of excessive dietary lipid consumption [7]. Although lipids are absorbed in the small intestine, some dietary fats escape absorption and reach the colon, leading to structure shifts in the gut microbiome [8]. Fats in the food matrix increase the bioaccessibility of polyphenols during digestion.…”

Seasonal Variation in Gut Microbiota Composition: Comparative Analysis of Siberian Musk Deer (Moschus moschiferus) and Forest Musk Deer (Moschus berezovskii)

“…For example, the content of animal protein and saturated fatty acids are related to the abundance of Actinomycetes, while the abundance of carbohydrates, monosaccharides (glucose and fructose) and the abundance of Pseudomonas and Prevotella are highly correlated. Bacteroidetes were more abundant in musk deer consuming a high-starch and high-protein diet during the summer; meanwhile, Firmicutes were more abundant in musk deer consuming a high-ber diet during the winter [31,40,41]. Except for various leaves, the food of captive forest musk is mainly carrots and various grains.…”

Diet quality and body mass indices show opposite associations with distal gut microbiota in a low-income cohort

“…Isolated genomic DNA was amplified using conserved degenerate primers targeting 16S rRNA gene V1-V2 and V4 regions as we described previously [13]. Two different regions were used in order to reduce biases in community composition estimates when only a single rRNA gene region is used.…”

“…The cell counts obtained independently for each sample based on the sequencing of V1-V2 and V4 16S rRNA gene regions were merged together into a single taxon abundance estimate via where A is an abundance value for each taxon. PIC-RUSt was used to predict total functional capacity of each subject's distal gut microbiome as we did previously [13]. Sequence dataset has been deposited into the Sequence Read Archive repository (BioProject ID PRJNA563912).…”

“…Whereas end-products of carbohydrate fermentation (various short chain fatty acids) have positive functions in the gut [10], protein fermentation is more detrimental to the host health because it results in the production of harmful hydrogen disulfide, phenolic compounds, and ammonia [11]. Less is known about colonic fermentation of dietary fatty acids, and the available evidence points to several detrimental effects on the host [12,13].…”