One of the greatest crusaders for vitamins died last month of cancer. Linus Pauling, Ph.D., the son of a pharmacist, was 93. Pauling, who valued his Nobel Prize for peace over his Nobel Prize for chemistry, took 18,000 milligrams of vitamin C a day. Pauling maintained the vitamin C delayed the onset of his cancer for 20 years.
For now, many researchers are less certain than Pauling was about the impact of vitamins on cancer and other diseases in light of some recent mixed results.
A four-year study published in the July 31 issue of the New England Journal of Medicine involved 864 people who already had developed one benign polyp of the colon. The researchers found that taking supplemental vitamins C, E and/or beta carotene failed to reduce the risk of developing additional polyps of the colon. Another widely publicized report concerning 29,000 heavy cigarette smokers in Finland, ages 50 and up, also published in the New England Journal of Medicine (April 14) did not find any reductions in lung cancer risk from taking daily supplements of 20-milligram beta-carotene and 50-milligram vitamin E over the course of five to eight years.
Beta-carotene takers actually had an 18% higher incidence of lung cancer, an unexplained result that the study's own authors say may be due to chance. In an editorial that accompanied the study, Dr. Charles Hennekens, professor of medicine at Brigham and Women's Hospital, Boston, said that when the smokers took the vitamins, it may have been a case of "too little, too late" to protect them.
However, the study also found men who took vitamin E had 34% fewer prostate cancers and 16% fewer colorectal cancers.
Vitamins C, E and beta-carotene, which the body converts to vitamin A, are known as antioxidants because they prevent the chemical reactions that create disease-causing oxygen molecules, called oxygen free radicals.
It has been theorized that antioxidant vitamins are why people who eat large amounts of fruits and vegetables, and avoid meats and animal fats, have lower rates of cancer.
The Council for Responsible Nutrition, a Washington-based trade association of nutritional supplement manufacturers, notes that major clinical and epidemiological studies in the United States, involving more than 140,000 subjects, have revealed no adverse effects of antioxidant nutrients, including beta-carotene.
The group describes the vitamin E doses of 50 milligrams daily used in the Finnish study as "modest," noting that two epidemiological studies conducted by Harvard University researchers showed a protective effect of vitamin E supplements against heart disease risk only in those who took at least 100 IU per day for at least two years.
Another study that has shown beneficial effects of antioxidants was sponsored by the National Cancer Institute and conducted in Linxian, China. That study, published in the Journal of the National Cancer Institute Sept. 15, 1993, found that a combination of beta-carotene, vitamin E and selenium reduced the risk of dying from cancer. A more definitive conclusion about the disease-preventing abilities of the antioxidants may hinge on the outcome of the ongoing Physicians' Health Trial. More than 20,000 U.S. physicians have taken 50 milligrams of beta-carotene every other day for more than 10 years, with no apparent ill effects. Indeed, in a subgroup of physicians with heart disease, beta-carotene was found to reduce the risk of coronary events by more than 40%. Cancer results from this trial are expected to be completed in 1996.
There is actually far less controversy concerning the effect of foods high in antioxidants. The investigators in the Finnish smokers' study said there may be something in foods containing beta-carotene that helps prevent disease that may not be contained in a single supplement of beta-carotene.
