The Council for Responsible Nutrition (CRN) believes that as long as the benefits of antioxidants are considered to be ripe topics for research, they will continue to be of legitimate interest to consumers and health care practitioners who want to be proactive in improving health, despite the efforts of the American Heart Association (AHA) to shut the door on antioxidant supplementation even while research continues.
Although there are some positive studies on antioxidants and heart disease, the Nutrition Committee of the AHA has concluded that antioxidant supplements should no longer be recommended for either primary or secondary prevention of heart disease, even while recognizing that more research is needed. According to the AHA Science Advisory appearing in the August 3 issue of Circulation, the epidemiological evidence strongly supports a beneficial effect of diets rich in a variety of antioxidants, and laboratory studies have established that antioxidant effects have a role in affecting the course of atherosclerosis. These findings led to the initiation of clinical trials with antioxidant nutrients, primarily vitamin E, vitamin C, and beta-carotene. Some of these trials have demonstrated benefits from antioxidant supplements, but most have not. Almost all of the studies have been conducted in people with heart disease or in high-risk populations, not in the general population.
The AHA Science Advisory notes: “The failure of these particular trials does not necessarily rule out a role for oxidative mechanisms in the pathogenesis of human atherosclerosis.” There are many different antioxidants, and we need more information about their specific effects in order to choose the best ones for further research. “Moreover, antioxidant treatment may need to begin earlier in life to be effective.” The epidemiological evidence is based on differences in disease risk in people who have had a lifetime exposure to diets rich in antioxidants, and the impact of such a diet may not be duplicated when researchers expose subjects to a single antioxidant or a limited antioxidant cocktail for a period of 5 years or so. “Clearly, further research is needed,” says the AHA Nutrition Committee.
“CRN agrees that further research is needed, and in the meanwhile people whose dietary patterns include the regular use of antioxidant supplements have no reason to change those habits,” said Annette Dickinson, Ph.D., president of CRN. “Antioxidants have been shown in some studies to enhance overall immune function, protect the eyes from cataracts and macular degeneration, slow the progression of Alzheimer’s disease, and reduce the risk of some cancers. In addition, while many of the studies on vitamin E and heart disease have been disappointing, some have been positive. The AHA seems to be trying to prematurely close the door on supplement use, even while more studies continue.”