Dietary Supplements

Should I take vitamins to prevent heart disease?

After looking at all the research on vitamin and mineral supplements, both the US Preventive Services Task Force and the American Heart Association concluded that they should not be taken for the purposes of preventing or treating heart disease. There is research showing that people who choose to take vitamin supplements (mostly vitamins A, C, E, and beta carotene) are less likely to develop heart disease. However, this is largely because men and women who take supplements tend to be leaner, wealthier, exercise more vigorously, eat healthier, and are less likely to smoke than nonusers.

Do vitamin E pills prevent heart disease?

No. Not long ago, vitamin E was touted as the heart-healthy vitamin of choice and it is the most studied. Among more than 87,000 women in the Nurses’ Health Study, those who happened to take vitamin E supplements for 2 years or more cut their risk of heart disease by 41% compared with nonusers. When researchers randomly assign people to take vitamin pills or dummy pills and follow them over time, you can be more confident that any benefit seen is due to the treatment because both groups are similar in terms of their risk factors for heart disease. The Women’s Health Study was done this way. It included nearly 40,000 healthy women older than 45 years and made half take vitamin E every other day (600 international units [IU]). There was no difference in the risk of cardiovascular problems including heart attack and stroke between women who took vitamin E and those who took dummy pills after nearly 10 years. Similarly, the HOPE trial included nearly 10,000 men and women at high risk for heart disease and found no difference in the risk of heart problems between the vitamin E supplement group (400 IU daily) and people taking placebo pills.

What about other vitamins and multivitamins?

Vitamin C and beta carotene have not been shown to lower the risk of heart problems as individual or combined supplements in either healthy people or people who already have heart disease. In 2 large studies, the B vitamins, including folic acid, did not reduce the risk of heart problems in men and women with heart and vascular disease. Vitamin A does not appear to protect against heart disease either.

Multivitamins usually have much lower doses of individual vitamins than single supplements. Most, but not all, studies show that multivitamins are not effective at reducing the risk of chronic diseases including heart disease. A report from the Women’s Health Initiative including more than 160,000 postmenopausal women found that, over a period of 8 years, women taking multivitamins did not have a reduced risk of developing heart disease, cancer, or of dying early compared to women who did not take multivitamins.

Are vitamin and mineral supplements ever harmful?

There is evidence suggesting that high doses of some vitamins and mineral supplements may be harmful. A study of more than 400 postmenopausal women with heart disease found that those assigned to antioxidants (400 IU vitamin E plus 500 mg of vitamin C twice daily) were more likely to die than women assigned to dummy pills. Another small study of 160 men with heart disease found that antioxidant supplements (vitamins C, E, beta carotene, and selenium) interfered with their cholesterol drugs. Beta carotene supplements appear to increase the risk of lung cancer and heart disease in men who smoke. High doses of vitamin A may reduce bone mineral density or cause liver damage; it is also associated with birth defects in pregnant women.

Can I get too much vitamins and minerals from food?

There is no evidence that eating foods rich in vitamins and minerals is harmful. The amounts of vitamins and minerals found in foods are much lower than in single vitamin supplements. However, pregnant women are advised to avoid getting too much vitamin A from foods (e.g., liver) or supplements because of the risk of birth defects. Vitamin and mineral supplements are not a substitute for a balanced, nutritious diet.

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