GLOSSARY

Microbial Metabolite is a microbial product or intermediate, with effects dependent on molecule, site, amount and host handling.

For sports use, do not jump from a mechanism to a definite performance effect; evaluate food, training, tolerance and actual goal-related change together rather than ending assessment at one marker.

Microbial metabolites are products or intermediates of microbial activity, sometimes further modified by the host. Not all are uniquely microbial: hosts also produce lactate and succinate. Location, amount and pathway determine interpretation. A metabolome describes measured chemicals rather than the living community. Detecting a compound without suitable methods does not establish its exact origin or a definite beneficial or harmful effect on the athlete.

Composition identifies detected groups; functional potential concerns genetic capacity, while activity concerns what is actually expressed or produced. Different communities can share functions. A gene's presence does not guarantee a particular metabolite output. Organism names alone therefore establish neither extra usable energy nor improved absorption, strength or recovery. Distinguish taxonomic detection, measured activity and meaningful human outcomes when assessing a microbiome claim.

One microbe's product can feed another; some use lactate or acetate within networks producing other metabolites. Cross-feeding makes community effects more complex than adding individual abundances. Lactate and succinate are not merely useless waste. However, identifying a laboratory pathway does not itself show that supplementing its intermediate or manipulating the community improves athletes. Net output depends on production, consumption and the organisms actually present in context.