Just a few years ago, many cardiologist, myself included, were encouraging you to take daily vitamin E supplements. The reasoning went like this: There are dangerous waste products called oxidants that build up inside our bodies, and these oxidants seem to play important roles in the development of heart disease and cancer. Vitamin E is a potent antioxidant, and, in epidemiological studies, people who had higher vitamin E intake either from food or supplements had lower rates of heart disease and cancer.
The case for vitamin E was convincing enough that an awful lot of doctors out there were taking vitamin E themselves. Some of them probably still are, but that is because they are clinging to old notions. For the last few years, a series of trials in which patients were given either vitamin E or a placebo have yielded discouraging results.
Still, many clung to hope because these trials tended to observe patients for relatively brief periods (for example, three to five years). A study published a couple of years ago dashed the hope that vitamin E supplements could lower risk of heart disease and cancer. The March 16, 2005 issue of Journal of the American Medical Association featured the longest trial comparing vitamin E versus a placebo to date — a seven-year study. There was no evidence of benefit. In fact, the data offered some reason for concern.
The study was called the Heart Outcomes Prevention Evaluation — The Ongoing Outcomes (HOPE-TOO) trial. The study included more than 9,000 patients at least 55 years old with vascular disease or diabetes. The subjects took either 400 IU (international units) of vitamin E or a matching placebo each day. Over the seven-year follow-up period, there was no evidence of a reduction in cancer or heart disease in the patients who took vitamin E. In fact, there was a 21% higher risk of hospitalization for heart failure.
The authors concluded that patients with vascular disease or diabetes should not take vitamin E. Their data probably ended interest in vitamin E supplements for virtually everyone else, too.
An accompanying editorial said that "this report effectively closes the door on the prospect of a major protective effect of long-term exposure to this supplement, taken in moderately high dosage, against complications of atherosclerosis and overall cancer incidence."
Now, this does not mean that the antioxidant theories of the 1990s were wrong. The data just imply that treating relatively healthy people with vitamin E as an antioxidant doesn't seem to be useful. Recent lab research suggests that vitamin E may be a good antioxidant, but it actually doesn't seem very effective at blocking the "oxidation" of LDL cholesterol, which is considered an important step in the development of atherosclerosis.
There are quite possibly some subgroups of patients and some conditions for which antioxidant therapy is useful, even with vitamin E. For example, patients with severe cases of an eye problem called macular degeneration seem to benefit from a cocktail of antioxidants including vitamin E. But patients with milder conditions apparently do not.
Perhaps other antioxidants will come along that do prove useful for preventing heart disease. But one enduring lesson from the vitamin E story is the same lesson learned from the postmenopausal hormone-replacement story. Epidemiological studies can generate theories about what might be beneficial, but we need the time, patience, and resources to perform major trials in which therapies are tested against placebos before we draw conclusions about what pills we should swallow every day.
Thomas H. Lee, M.D. is the chief executive officer for Partners Community HealthCare Inc. He is a professor of medicine at Harvard Medical School. He is an internist and cardiologist at Brigham and Women's Hospital. Dr. Lee is the chairman of the Cardiovascular Measurement Assessment Panel of the National Committee for Quality Assurance.