MICRONUTRIENTS AND BREAST-CANCER

A large part of the epidemiological debate on diet and breast cancer h as been dominated by the issue of whether fat, particularly animal fat , increases risk. Lately, the possible protective effect of various di etary constituents has received more attention. Vitamins C and E, and beta-carotene have antioxidant activity and may thus provide a cellula r defence against reactive oxygen species that damage DNA. Dietary fib re may influence oestrogen metabolism. A large case-control study (2,5 69 breast cancer and 2,588 hospital controls) conducted in six Italian areas between 1991 and 1994 suggested that a diet rich in several mic ronutrients was associated with significantly lowered risk. After allo wance for non-dietary risk correlates, energy intake and the mutual co nfounding effect of the various micronutrients, beta-carotene, vitamin E and calcium were associated with odds ratios in the highest intake quintile compared to the lowest one of 0.84, 0.75 and 0.81, respective ly. Among different types of fibre, only cellulose intake showed a mod erate inverse association. Evidence from other studies suggests that a favourable role of some micronutrients is possible, albeit probably l ess important than for cancers of the stomach and colon-rectum. Indeed , the relationship between fruit and vegetable intake is also less mar ked/consistent for breast cancer than for other sites. Among agents th at have only recently been investigated, isoflavones, which are weak o estrogens, are of particular interest.