Inhibition
Vegan and vegetarian diets appear to select against gut flora that metabolize carnitine (in favor of other gut flora more coordinated with their food supply). This apparent difference in their microbiome is associated with substantially reduced gut bacteria capable of converting carnitine to trimethylamine, which is later metabolized in the liver to TMAO.[10]
3,3-Dimethyl-1-butanol (DMB), a structural analog of choline, inhibits microbial TMA formation in mice and in human feces, thereby reducing plasma TMAO levels after choline or carnitine supplementation.[8] It is found in some balsamic vinegars, red wines, and some cold-pressed extra virgin olive oils and grape seed oils.[8]