November 29, 2004
Many people with Alzheimer's or at risk for the disease take vitamin E to protect the brain from damage. But, a new study shows, taking the popular vitamin supplement may do more harm than good. High doses of the vitamin, a new research initiative reveals, appear to actually increase the overall risk of dying.
Researchers at the Johns Hopkins Medical Institutes analyzed data from 14 studies involving more than 136,000 people. They concluded that taking vitamin E supplements at high doses, over 200 IU (International Units) a day, can increase the risk of having a heart attack and, in their opinion, should be avoided. The more vitamin E someone took, the greater his or her overall risk of death. Although the risk was small, it was worrisome. Someone taking 400 IU of vitamin E a day for five years, for example, faced a 5 percent higher risk of dying, the investigators found.
Many people who take vitamin E take doses of 400 to 800 IU a day or higher. It's important to note, though, that many of these people take the vitamin because they suffer from heart disease or cancer or are at high risk for these ailments and have been advised to take vitamin E by their physicians. Such people have a higher risk of dying in general, primarily because they have or are at high risk for these serious ailments. The authors of the current study concede that they are not sure how much of the increased risk of dying is due specifically to vitamin E and how much is due to the general health status of the study participants.
"A lot of people take vitamins because they believe it will benefit their health in the long term and prolong life," said Edgar R. Miller III, an associate professor of medicine at the Johns Hopkins University School of Medicine, who led the research. "But our study shows that use of high-dose vitamin E supplements certainly did not prolong life but was associated with a higher risk of death."
Other groups, such as the Council for Responsible Nutrition (CRN), which supports the vitamin industry, issued statements saying the findings were overstated. "There is a small statistical effect here that they have found, but we don't believe it's necessarily an important biological effect," said CRN president Annette Dickinson. "We think they've overstated the importance of the findings." They point out that most of the people studied were already ill with heart disease, cancer, Alzheimer's, and other grave ailments. Therefore, they argue, the findings may not apply to the healthy population in general. Indeed, many studies have concluded that vitamin E is very safe.
More Is Not Better
The findings raise new concerns, however, and add to evidence that taking high amounts of single vitamins and other nutrients may be hazardous to your health. Researchers are not sure why high doses of vitamin E may be dangerous, although some studies suggest they may have unhealthful effects on blood clotting. Some doctors are concerned that patients taking several medications may be particularly at risk if they also take very large doses of vitamin E. That's because the liver both breaks down medications and also stores vitamin E. Very large doses of fat soluble vitamins, like E, might slow the liver's ability to process and get rid of spent medications.
Doses of vitamin E of 200 IU a day or less, however, did not pose any risk of increased harm. In fact, these lower doses may offer some benefits, the researchers found. More research is needed on the effects of low doses of vitamin E, as well as taking vitamin E along with other nutrients, such as vitamin C. In addition, vitamin E comes in various forms, both natural and synthetic, and some forms may be more beneficial than others.
Individual vitamin E pills are commonly sold in strengths of 400 IU or 1,000 IU. A multivitamin pill contains much less vitamin E, typically 30 to 60 IU. Foods, such as corn, nuts, seeds, spinach and leafy greens, olives, and asparagus, typically supply about 10 IU per day. Many doctors themselves take vitamin E to protect against heart disease, cancer, Alzheimer's, and other ills. Although the "best" dose is unknown, many recommend 400 IU once or twice a day.
Vitamin E supplements are commonly recommended as a treatment for Alzheimer's disease. They are also often recommended to help protect against heart disease, cataracts, cancer, and other ills. The vitamin acts as an antioxidant, sopping up excess "free radicals" that can damage cells throughout the body, including in the brain. Free radicals are highly reactive oxygen compounds formed during the normal course of cell activity, and an excess of them can damage the membranes that surround healthy cells. One of vitamin E's primary functions is to protect cell membranes and mop up free radicals.
A number of studies have been conducted on the effects of vitamin E and other antioxidants on Alzheimer's disease. A large population study in 2002, for example, suggested that getting plenty of vitamin E from foods or vitamin pills may protect against mental decline. Other studies have found that a combination of antioxidants, including vitamins E and C and coenzyme Q10, may offer benefits. However, there is no strong evidence to date that vitamin E or other antioxidants indeed protects against the development of Alzheimer's or slows progression of disease. Additional studies are under way.
Regardless of what the outcome of these studies reveals, experts advise eating a heart-healthy, vitamin- and mineral-rich diet containing plenty of fresh fruits, vegetables, and whole grains. If you take vitamin E or have questions about the vitamin:
- Check with your doctor about whether you should be taking vitamin E.
- Always let your doctor know if you are taking vitamin E or other nutritional supplements. Vitamin E, for example, can interfere with "blood thinners" and other medications and can interfere with surgery.
- Check our site regularly for more updates on vitamin E and Alzheimer's. More research needs to be done to confirm if the vitamin has any benefits for the brain and whether benefits outweigh potential risks.
Click here for more on how foods, vitamins, and your diet can affect Alzheimer's disease.
American Heart Association, Annual Meeting, New Orleans, November 2004. Edgar R. Miller III, MD, PhD, Roberto Pastor-Barriuso Ph.D.; Darshan Dalal M.D., M.P.H.; et al: "Meta-Analysis: High-dosage Vitamin E Supplementation May Increase All-Cause Mortality." Annals of Internal Medicine, Volume 145, Issue 1, 4 January 2005.