Antioxidants Fail to Slow Cancer, Study Finds

Antioxidant vitamins, often touted as a way to ward off cancer, fail to prevent the development of precancerous growths in the colon, a study shows.

The research is the latest to cast doubt on the popular but largely unproven notion that extra doses of these nutrients provide a shortcut to good health.

Beta carotene and Vitamins C and E were tested on 864 men and women who had already been treated for colorectal adenomas, polyps that precede cancer. Among the 751 who completed follow-up tests, researchers found no signs that the vitamins had stopped them from getting more colon growths.

“A great deal of money is being spent to market the concept that taking additional vitamins will stop cancer. This particular study does not suggest that,” said one researcher, Dr. John A. Coller of the Lahey Clinic in Burlington, Mass.

The study was published in Thursday’s issue of the New England Journal of Medicine.

In April, the journal carried a study showing that Vitamin E and beta carotene, which is the vegetable form of Vitamin A, failed to protect smokers from lung cancer. In fact, that study reached the surprising conclusion that beta carotene was associated with an increased risk of cancer.

Those vitamins had seemed to be an especially promising way to attack colon cancer, although earlier, smaller studies produced conflicting results.

People who eat lots of fruits and vegetables are less likely to get colon cancer. Many assumed that the key was the relatively large amount of antioxidant vitamins in fruits and vegetables. Antioxidants soak up hazardous oxygen molecules called free radicals.

In the latest study, volunteers were randomly assigned to take dummy pills or daily vitamin supplements. Of that group, 751 underwent colon exams after one year and four years later to check for new adenomas.

The doctors found that the vitamins made no difference in the risk of precancerous growths.

Of the 113 patients who did not complete the study, 44 died, 32 no longer wished to participate, 19 were too ill or had moved and 18 dropped out for unknown reasons.

Patients who received the vitamins took 25 milligrams of beta carotene, one gram of Vitamin C, 400 milligrams of Vitamin E or a combination of the three.