For the past few years the “battle against cancer” includes taking lots of fruits and vegetables-five servings a day-and ingesting vitamins, especially vitamin E and beta carotene, and the mineral selenium. But other measures that are often assumed — and marketed — as ways to prevent cancer are either wrong-headed or nonsensical according to researchers.
The evidence about fruits and vegetables is vague, “far from definitive,” and therefore unproven. Fiber, found in fruits, vegetables and grains, has been touted to prevent colon cancer, even though two large studies found no effect. As for low-fat diets, long advertised to prevent breast cancer, a large federal study randomizing women to a low-fat or normal diet and looking for an effect in breast cancer found nothing.
Then there’s exercise and weight loss, always a good bet to achieve longevity and glowing health. Studies have associated strenuous exercise with less cancer. But that is the same sort of evidence that misled scientists about aspects of diet. “I think it’s wishful thinking,” said Dr. Susan Love, a breast surgeon. “We would like things to be more in our control. I think that’s part of it. And in the absence of anything else, what do we tell women about how to prevent breast cancer? We tell them to exercise and eat a good diet.”
Another study proposed would have been the largest cancer prevention clinical trial ever attempted, involving 35,000 men 50 and older. This time the idea was that vitamin E and selenium might prevent prostate cancer.
The selenium and vitamin E study ended early. Once again, there was no protection from cancer, and there were hints the supplements might be causing cancer. The great hope, after more millions spent on scientific imaginings, again turned into profound disappointment.
Other measures that are often assumed — and marketed — as ways to prevent cancer may not make much difference, researchers say. The key word is “marketed,” or is it “junk science”?