Expert warns of risks in high doses of supplements

Published on Monday 19 October 2009 01:40

PEOPLE taking high-dose vitamin and mineral supplements may be doing more harm than good, an expert said last night.

Professor Martin Wiseman, medical and scientific adviser for the World Cancer Research Fund (WCRF), said it was difficult to predict the impact vitamin supplements had on the chances of cutting cancer.

While low dose supplements can be a "valuable safety net", high doses could be harmful.

Research over the past few years has suggested some vitamins can actually increase the risk of some cancers. For example, beta carotene can increase the risk of lung cancer in people who already smoke.

Prof Wiseman said: "Although there are some studies that have shown a reduction in cancer risk from high-dose supplements, others have not, and these supplements have normally only been tested on a select group of people.

"This means we simply do not know enough about what the effect will be for the general population to predict confidently the balance of risks and benefits. Some people may be doing themselves more harm than good.

"There are also studies that show high doses of some supplements can increase risk of some cancers."

Prof Wiseman said multivitamins would not contain all the good nutrients found in food, such as fibre.

"The best advice is to have a healthy, plant-based diet with lots of fruits and vegetables, rather than relying on supplements," he said.