Ascorbic acid bioavailability in foods and supplements.

The bioavailability of ascorbic acid from food has been assumed to be high, but little quantitative information has been available to substantiate this assumption because of the limited precision and low statistical power of previous studies. A recent depletion-repletion study with a more effective experimental design has shown clearly that ascorbic acid bioavailability is equivalent in ascorbic acid tablets (with and without iron), orange juice, whole orange sections, and cooked broccoli. The bioavailability of ascorbic acid in raw broccoli was 20% lower, although this difference would probably have little nutritional significance in typical mixed diets.