Vitamins 'do not cut cancer risk'

Both trials were set up following some evidence that taking supplements might have a positive effect.

But one study of 35,533 men, and a second of 15,000 doctors, found no evidence that cancer rates were any lower in those taking supplements.

Both studies feature in the Journal of the American Medical Association.

Supplements don't substitute for a healthy diet and some studies have shown that they may actually increase the risk of cancer
Dr Jodie Moffat
Cancer Research UK

A number of trials had suggested that taking vitamins could cut the risk of certain cancers by boosting levels of beneficial antioxidants which work to minimise damage in the tissues, but the results were mixed.

The latest studies set out to come up with more definitive results, by involving large numbers of volunteers.

In the first study, researchers from University of Texas and the Cleveland Clinic Lerner College of Medicine gave healthy men either the trace mineral selenium, vitamin E, both or a dummy pill.

The team intended to monitor all the participants for at least seven years but the trial was stopped early because the results were so disappointing.

The researchers found there were no statistically significant differences in the numbers of men who developed prostate cancer in the four groups.

In all cases the proportion of men diagnosed with prostate cancer over a five-year period was 4% to 5%.

In the second study, researchers at Boston's Brigham and Women's Hospital tested the impact of regular vitamin E and C supplements on cancer rates among 14, 641 male doctors.

Over eight years, taking vitamin E had no impact at all on rates of either prostate cancer, or cancer in general. Vitamin C had no significant effect.