Carboxylic acids are food for the bacteria and host cells and also have a regulatory effect on them. First of all, they act upon the own microbiota cells. Carboxylic acids and other metabolites, depending on their concentration and composition, have a stimulatory effect on the growth and activity of some microorganisms and inhibit the development of others. Generally, the effect is directed at optimizing the functions of all microbiota.
Acetate (acetic acid salt), and lactate (lactic acid salt) adjust the pH level, motion and secretory activity of the intestine, have laxative and antimicrobial effects.
Some of amino acids (glutamic acid, methionine, lysine, leucine, etc.) have a pronounced stimulating effect in relation to normal flora and the probiotic bacteria. Glycine regulates the amount of bacteria cells.