Biologically important bacteria can perform a variety of functions in the gut from the production of short-chain fatty acids (SCFAs) to hormones and neurotransmitters to pro-inflammatory compounds. Gut bacteria feed primarily on non-digestible carbohydrates, but some microorganisms can also utilize amino acids and fatty acids for survival. Fibers and amino acids can reach the gut microbiome by avoiding digestion and absorption. Many fibers are not digestible by the human GI tract and can thus feed the gut microbiome by design, but maldigestion and malabsorption can also allow carbohydrates and proteins to enter the gut microbiome and act as substrates for bacterial fermentation.
Gut microbes can produce some protease enzymes to help promote protein digestion and fermentation in the gut, but amino acid fermentation requires more interconversion and expends more energy than carbohydrate fermentation, so amino acids are not generally considered to be as efficient of an energy source for the human gut microbiome. When it comes to nutrients that bypass digestion and absorption in the digestive tract, gut bacteria preferentially choose carbohydrates over protein and protein over fat. Balance is key with any diet, but nondigestible fibers are crucial for an efficient, highly functioning gut microbiome. Furthermore, salt intake appears to have a negative effect on SCFA production. In fact, a recent study found that adults who reduced their sodium intake to the recommended 2300 mg/day experienced a sharp increase in all forms of SCFAs. These effects were noted in both men and women, but the results were significantly more significant in women.
This simple at-home test shows practitioners the abundance of 10 important keystone species, 34+ pathogens plus virulence factors, microbial cross-feeding relationships, and an analysis of 20+ functions of the microbiome.