Cellular functions of ascorbic acid: a means to determine vitamin C requirements.

Optimal ascorbic acid (vitamin C) requirements in humans are unknown. In situ kinetics is a biochemical approach to determine requirements for vitamin C and other vitamins. In situ kinetics requires that cellular functions of ascorbic acid are characterized. Vitamin-C-dependent cellular reactions are directly related to vitamin C concentrations inside and outside cells. By coupling intracellular and extracellular functions of ascorbic acid to vitamin concentration, in situ kinetics provides a novel approach to determining vitamin C requirements.