Mechanisms of Action
Half-Life
The time required for the body to eliminate half of a substance's active amount.
Biological half-life is the time required for the body to reduce the concentration of a substance (supplement, nutrient, or metabolite) to half of its initial value through metabolism and excretion. Half-life determines dosing frequency — substances with short half-lives (e.g., vitamin C at ~2 hours) may benefit from divided daily doses, while fat-soluble vitamins with long half-lives (e.g., vitamin D at ~2-3 weeks) can be taken less frequently. Understanding half-life is crucial for designing supplementation protocols and interpreting washout periods in clinical trials.