A systematic review of published studies into the various benefits of vitamin and mineral supplements found insufficient evidence to prove or disprove that they are effective in preventing cardiovascular disease (CVD), cancer, or mortality from those diseases in healthy adults.
The article published in Annals of Internal Medicine concluded that more research was needed to determine whether or not these benefits are actually obtained.
Two studies included in the review found lower overall cancer incidence in men who took a multivitamin for over 10 years, but those same studies showed no cancer protection benefit for women.
The evidence review was conducted by researchers for the United States Preventive Services Task Force (USPSTF) to update its previous recommendation.
In 2003, this same body found insufficient evidence to recommend for or against the use of vitamins A, C, and E multivitamins with folic acid, or antioxidant combinations for the prevention of CVD or cancer.
At the time, the USPSTF recommended against beta-carotene supplements alone or in combination with other supplements because they had no benefit and actually harmed patients at risk for lung cancer.
The current research review reconfirmed the beta-carotene findings and also found good evidence that Vitamin E does not protect against cancer or cardiovascular disease.