A mutualistic relationship is a relationship in which both organisms benefit. Research in the field of microbiome-host interaction shows more and more that it is not just a matter of humans (i.e. the host) giving the commensal bacteria a space to live and thrive, but also that gut bacteria provide the host with health benefits. One of the ways in which they do this, is by producing small molecules (or metabolites), with a strong influence on our health.
Short Chain Fatty Acids (SCFAs)
Some of the best described metabolites produced by gut bacteria are the short chain fatty acids acetate, propionate and butyrate. Especially butyrate has often been linked to gut health. Butyrate is the main energy source for colonocytes (i.e. epithelial cells of the colon), and is thus associated with maintenance of the epithelium. Moreover, butyrate is in high interest because of its various beneficial mechanisms in human health, related to allergy, inflammation, satiety (for weight management concern), oxidative stress, glucose and fat metabolism.
Butyrate is only produced by commensals, in two ways:
1. Indirect via cross-feeding by other bacteria, or
2. Direct production by commensal bacteria such as F. prausnitzii, E. halii, E. rectale, and Roseburia spp
Fibers are food for commensals
In the next Newsletter we dive deeper into the substrates (i.e. food) commensals need to produce health promoting metabolites, specifically butyrate. It turns out that what you eat is not only your food but also food for your commensals. Depending on what you eat, you give them fuel to produce specific metabolites. Research shows that fibers, or prebiotics, are the right food for your commensals.