Men who took vitamin E or vitamin C supplements were no more or less likely to develop cancer than men given a placebo, indicating these antioxidants have no cancer-prevention value, U.S. researchers said on Sunday.
Previous research showed that people who ate diets rich in vitamins E and C had a lower risk of cancer, suggesting that supplements of these vitamins might help ward off cancer, the researchers said.
The new study tracked cancer risk in 14,641 male U.S. doctors who took either 400 IU of vitamin E every other day or a placebo, or 500 milligrams of vitamin C daily or a placebo. Their average age was 64 at the start of the study and they were followed for eight years on average.
Taking the vitamins had no impact on the risk for any type of cancer, Howard Sesso of Harvard Medical School and Brigham and Women's Hospital in Boston and colleagues reported at a meeting of the American Association for Cancer Research.
Vitamins don't prevent heart disease, either
One week ago, Sesso reported in the Journal of the American Medical Association that in the same population of men, taking these vitamins also failed to reduce their risk of cardiovascular disease including heart attack and stroke.
"In our view, there's really no compelling reason to take these individual vitamin E and C supplements," Sesso said in a telephone interview. "Until other evidence comes out otherwise, we would argue that without any clear benefit, why would you take these?"
Vitamin E and vitamin C are antioxidants, thought to protect against damage caused by free radicals, substances that can harm cells, tissues and organs. Fruits and vegetables are rich in both, and it has been shown that people who eat plenty of these foods may have a lower risk of heart disease, cancer and other conditions.
The researchers were particularly interested in whether vitamin E supplementation would reduce the risk of prostate cancer after earlier research suggested it might. It did not.
There has been controversy over vitamin C and cancer for decades. The idea that vitamin C, also known as ascorbic acid, could be used to treat cancer was advanced in the 1970s by American scientist Linus Pauling, who awarded the Nobel Prize in chemistry in 1954.
Sesso said an ongoing element of his research is looking at whether taking a multivitamin combining a number of different vitamins has any effect on the risk for cancer and cardiovascular disease.