BALTIMORE, MARYLAND. There is ample evidence that lipid peroxidation (oxidation of fats) is an important contributor to atherosclerosis, particularly in the early stages. The extent of lipid peroxidation can be determined by measuring the amount of F2-isoprostanes in the urine. F2-isoprostanes are formed in the body by free radical catalyzed peroxidation of arachidonic acid.
A team of American and Australian researchers reports that both vitamin C and vitamin E markedly reduce
the formation of isoprostanes. Their study involved 184 non-smoking men and women who were
randomized to receive either 500 mg/day of vitamin C (ascorbate), 400 IU/day of synthetic vitamin E (alpha-
tocopheryl-acetate), 500 mg/day of vitamin C + 400 IU of vitamin E or a placebo for a two-month period.
The researchers observed a marked reduction in urinary isoprostanes in the groups taking vitamin C,
vitamin E or vitamin C + vitamin E. The reduction in the vitamin C + vitamin E group was, however, no
greater than the reduction observed in the groups taking vitamins C and E separately. This would indicate
that the two vitamins do not act synergistically in reducing lipid peroxidation. The researchers also observed
that vitamin C, but not vitamin E, significantly increased the blood serum's capacity to resist oxidative
damage (ORAC value). They conclude that both vitamins C and E markedly reduce lipid peroxidation, an
important precursor of atherosclerosis.