Mechanisms of Action
Bioavailability
The proportion of a supplement that is absorbed and available for use by the body.
Bioavailability refers to the fraction of an ingested supplement that reaches systemic circulation in its active form and is available at the site of action. Factors affecting bioavailability include the chemical form of the nutrient, food matrix interactions, gut pH, intestinal permeability, first-pass liver metabolism, and individual genetic variations in metabolizing enzymes. For example, curcumin has less than 1% bioavailability in its natural form but 20-185x enhancement with specialized delivery systems. Understanding bioavailability is essential for interpreting supplement research and choosing effective forms.