DOCTOR'S VIEW ARCHIVE
Carolyn Janet Crandall, MD, MS, FACP
Medical Editor: William C. Shiel, Jr, MD, FACP, FACR
Should women take antioxidant supplements?
The idea of antioxidants for heart protection sounds great. This is because in the research laboratory oxidation plays a big role in formation of atherosclerotic plaque (the cholesterol-formed substance that can eventually rupture to cause a heart attack).
If oxidation is bad, shouldn't antioxidant supplements be helpful for the
In the last several years, the long-awaited reliable scientific studies (large, controlled clinical studies) were finally performed to test whether antioxidant supplements really protect the heart. Heart protective effects of antioxidant supplements have been tested on more than 100,000 people in recent well-designed trials. To date, trials have been completed for vitamin E (5 large trials), beta-carotene (3 large trials), and antioxidant mixtures (2 large trials). Each of these trials showed no effect of antioxidant supplements on cardiovascular disease occurrence. Only a few controlled clinical studies showed beneficial effect for vitamin E (with or without vitamin C), and those studies were performed in people who already had heart disease, or were at high risk of heart disease. As a result, the American Heart Association released a "Science Advisory" regarding antioxidant vitamin supplements and cardiovascular disease. The statement concluded that scientific data does not justify the use of antioxidant vitamin supplements for reducing cardiovascular risk.
Similarly, the U.S. Preventive Services Task Force (USPSTF), which constructs guidelines that doctors use in clinical practice based on strict scientific review of clinical research, reviewed all the clinical research regarding the role of antioxidants in cancer and heart disease. The USPSTF concluded that there is insufficient evidence to recommend either for or against the use of supplements of vitamins A, C, E, or antioxidant combinations for the prevention of cancer or cardiovascular disease. Furthermore, because some studies actually proved harm resulting from particular antioxidant supplements, USPSTF specifically recommends against the use of beta-carotene supplements, either alone or in combination for prevention of cancer or cardiovascular disease. Not only did beta-carotene not protect against cancer or cardiovascular disease, but it actually increased the risk of lung cancer and the chance of dying in studies of smokers. (Of course, these recommendations are not meant to apply to people who have diagnosed vitamin deficiencies that require treatment.)
We've learned some lessons along the way...
Antioxidant compounds cannot just be lumped together, as they each have distinct effects. Starting antioxidant supplements earlier in life may be required for heart protection. Moreover, it may be difficult to find heart disease benefits of antioxidant supplements in studies that in general, were under 5 years in duration, compared to a life-long diet rich in antioxidants. Obviously we have much to learn about the details of the oxidization-antioxidation balance.
The bottom line is that for better or worse, a diet high in antioxidants from food sources, just doesn't translate to taking antioxidants as supplements for heart protection. Vitamin supplements don't take the place of a healthy diet.