Nutritional lipid and antioxidant supplements: risks versus benefits

Two of the dietary tenets of the free radical theory of cancer, put forth by Denham Harman in 1962, require, in deference to newly accrued knowledge, refinement. The first was a recommendation for dietary reduction of vulnerable free radical targets, for example, polyunsaturated lipids. The second was the addition of one or more antioxidants to the diet. With respect to the first, it is now known that the equivalent levels of dietary ω-6, -3 polyunsaturated fatty acids (PUFA) have opposite effects upon photocarcinogenesis. Increasing levels of ω-6 PUFA exacerbate photocarcinogenesis, with regard to decreased tumor latent period and tumor multiplicity. Dietary ω-3 PUFA inhibits photocarcinogenesis, increasing tumor latent period and reducing tumor multiplicity. Yet the degree of unsaturation in both types of fats is almost equal. It is almost certain that the action of these two types of PUFA rests with the intermediates that each generates through the lipoxygenase and cyclooxygenase pathways. The general ...