The intermediate end product of metabolism. The term metabolite is usually restricted to small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory, and inhibitory effects on enzymes, defense, and interactions with other organisms. A primary metabolite is directly involved in normal “growth”, development, and reproduction.

As bacteria carry out the activities they need to sustain themselves (their version of ‘eating’) they take bigger compounds and turn them into smaller compounds called metabolites (or “small molecules”). Metabolites are naturally formed as substances are broken down. Basically, metabolites are a little like bacterial poop: the end product of what they metabolize.

Most molecules are small (obviously) but metabolites are officially called “small molecules” because they have a lower molecular weight than, say, protein molecules. This allows them to enter and interact with other cells. Bacteria in the gut produce various metabolites when they break down non-digestible carbohydrates (i.e. dietary fibers), including short-chain fatty acids like butyrate (which powers your cells), that can benefit your health.