Bioavailability is the proportion of an ingested dose that reaches systemic circulation in an active form. It explains why two products with the same label dose can differ in effect: a poorly absorbed form (or one degraded in the gut) delivers less than a smaller, better-absorbed or formulated version. It is a key reason to compare forms, not just milligrams.
Related terms
- Third-party tested
- Independent lab verification that a supplement matches its label and is free of meaningful contaminants.