Interaction of vitamin E and ascorbic acid (review).

Ascorbic acid appears to have two opposite roles in animal tissues: to act as an antioxidant or to act as a prooxidant. The effects of ascorbic acid supplementation on the tissue antioxidant status seem to be dependent on the dose of ascorbic acid and the vitamin E status. Adequate doses of ascorbic acid supplementation to vitamin E-deficient subjects or animals help to partially maintain vitamin E levels, probably through sparing the degradative metabolism of vitamin E, and thus increase the antioxidant effectiveness. The sparing effect of ascorbic acid on vitamin E metabolism is also shown in the partial reversal of the manifestation of vitamin E deficiency. On the other hand, when the animals are marginally adequate in vitamin E status, ascorbic acid supplementation in large doses appears to promote lipid peroxidation and significantly decreases the antioxidant potential of animals. An increase of the level of vitamin E supplementation overcomes the prooxidant effect of large doses of ascorbic acid. This observation suggests that vitamin E requirement may be increased with a large dose of ascorbic acid supplementation.