In people without nutritional deficiencies, vitamin and mineral supplements do not reduce the risk of heart disease or cancer

Fortmann SP, Burda BU, Senger CA, et al. Vitamin and mineral supplements in the primary prevention of cardiovascular disease and cancer: An updated systematic evidence review for the U.S. Preventive Services Task Force. Ann Intern Med. 2013;159:824-34.

Review question

In people who do not have nutritional deficiencies, does taking vitamin and mineral supplements reduce the risk of heart disease and cancer?

Background

People often take vitamin and mineral supplements to prevent diseases such as cancer and heart disease. However, it is unclear whether vitamin and mineral supplements are helpful or harmful in generally healthy people with no nutritional deficiencies.

How the review was done

The researchers did a systematic review, searching for studies that were published up to January 2013.

They found 26 studies (24 randomized controlled trials), including 337,967 people (average age 22 to 77 years).

The key features of the studies were:

• people did not have nutritional deficiencies and had no heart disease or cancer at the beginning of the studies;
• vitamins that were assessed included multivitamins, beta-carotene, vitamin E, selenium, vitamin A, vitamin C, folic acid, vitamin D, calcium, and vitamin D plus calcium; and
• outcomes were measured after less than 10 years in most studies (range 6 months to 18 years).

What the researchers found

Men who took multivitamins for more than 10 years may be less likely to develop cancer. The same benefit was not seen in women. Researchers do not understand why there is a difference according to gender and warn that these results may not be accurate.

In people at high risk for lung cancer (smokers and people exposed to asbestos), beta-carotene increases risk of lung cancer.

Other vitamins and minerals were not found to affect death, heart disease, or cancer.

Conclusion

In people who do not have nutritional deficiencies or a history of heart disease or cancer, there is little evidence of benefits from taking vitamin and mineral supplements.