Assessment of vitamin C status

Abstract For centuries, the consumption of citrus fruit has been associated with the prevention of the vitamin C deficiency disease scurvy, but it was not until 1932 that the active compound was isolated (King and Waugh, 1932; Svirbely and Szent-Gyo¨rgyi, 1932). A year later, ascorbic acid was characterized and synthesized. The term “ascorbic acid” is now used to embrace both L-ascorbic acid and dehydroascorbic acid; both have approximately equal vitamin C activity. Ascorbic acid is the enolic form of an α-ketolactone (2,3-didehydro-Lthreo-hexano-1,4-lactone), which in solution is then easily oxidized to the diketo form — dehydro-L-ascorbic acid; their structures are shown in Figure 19.1.