Fruit and vegetable antioxidants could significantly reduce cancer risk

June 25,  2003

Eating sufficient fruit and vegetables to maintain antioxidant vitamin and mineral levels could reduce the risk of cancer and mortality in men, report researchers from the French health and medical institute Inserm.

An eight-year study found a 30 per cent reduction in cancers and 37 per cent reduction in mortality among men who received a daily antioxidant supplement compared to placebo. The researchers claim that the study, called SU.VI.MAX, is the first randomised trial to show that an adequate intake of vitamins and minerals from fruit and vegetables can reduce the risk of cancer.

The double-blind, placebo-controlled study tested the impact of a daily dose of antioxidants on 13000 healthy subjects. The dose included 6mg of beta-carotene, 120mg of vitamin C, 30mg of vitamin E, 100ug of selenium and 20mg of zinc. The 7886 women, aged 35 to 60 years old, and 5141 men, from 45 to 60 years old, were divided into two groups and followed up over an average of 7.5 years.

There was no difference between the two groups concerning heart disease, supporting other studies testing the effects of antioxidants on cardiovascular health, but cancer risk was reduced by 31 per cent among men. This included most cancers, especially digestive, respiratory and skin cancers.

The absence of such effects in women was not due to the different cancers they developed but rather their better state of health at baseline, explained the Inserm researchers.

Again, while risk of death was 37 per cent lower among men receiving the supplements, the same effect was not seen in women. The researchers also found a higher risk of cancer and heart disease among men with the lowest levels of beta-carotene. The lower the level of the nutrient, the higher the risk of disease. The team stressed however that the findings should support a nutritious diet with regular consumption of fruit and vegetables rather than supplements.

Use of antioxidant supplements was necessary to be able to compare to placebo, but they claim that this effect applies equally to nutrients found readily in plant foods. The results back nutrition advice to consume at least five portions of fruit and vegetables daily rather than relying on supplements, claim the researchers.

They add that the observed effect is likely weaker than would be seen from fruit and vegetables, which have additional nutrients not included in the supplement used in the study. Further, they pointed to fears that people taking supplements may eat less fruit and vegetables, calorie sources which often lead to reduction in consumption of fatty and sugary products.