Antioxidants seen ineffective against cancers

LONDON -- In another blow to the belief that antioxidant supplements improve health, an authoritative analysis has concluded there is no evidence the vitamins ward off digestive cancers.

Some experts say, however, that the findings do not mean the cancer-fighting potential of antioxidant pills should be written off.

In the report, published this week in The Lancet medical journal, scientists pooled the results of 20 years of research involving more than 170,000 people considered at high risk of developing gastrointestinal cancers. Antioxidant supplements investigated included vitamins A, C and E, as well as selenium, in a total of 14 trials.

"The antioxidant pills -- except selenium -- are useless for prevention of gastrointestinal cancers," said Dr. Goran Bjelakovic, who led the study for the Cochrane Heptao-Billary Group at Copenhagen University Hospital in Denmark. The Cochrane organization is a well-regarded international network of experts that produces systematic reviews of evidence on a variety of health interventions.

Bjelakovic said the group concluded the potential for selenium to combat liver cancer needs a closer look, but that further studies investigating the cancer-fighting effects of vitamins A, C and E would be a waste of time.

The connection between health and antioxidants got much attention after some studies suggested they blocked the heart-damaging effects of oxygen on arteries and the cell damage that might spur some kinds of cancer. Studies examining large populations have also found a link between a diet rich in antioxidant-loaded fruits and vegetables and lower rates of cancer and heart disease.

But when the theory was tested further by giving some people vitamin pills and others fake tablets and following them up for a few years, the supplements generally showed no benefits.