Multivitamin Use and Risk of Cancer and Cardiovascular Disease

In a recent study on vitamin and supplement use, Marian L. Neuhouser, Ph.D., of the Fred Hutchinson Cancer Research Center, Seattle, and other WHI colleagues analyzed data collected from all 161,808 participants in the Women’s Health Initiative, including those in the Hormone Trials, Dietary Study, and Observational Study. Their findings are reported in the Feb 9, 2009 issue of Archives of Internal Medicine.

About half of Americans use dietary supplements, spending more than $20 billion per year on these products, according to the article. “The motivations for supplement use vary, but common reasons include the belief that these preparations will prevent chronic diseases, such as cancer and cardiovascular disease,” the authors write. “These views are often fueled by product health claims, consumer testimonials and an industry that is largely unregulated owing to the 1994 Dietary Supplement and Health Education Act.” Scientific data supporting the benefits of supplements—including multivitamins, the most commonly used supplements—are lacking.

This lack of scientific data led Neuhouser and her colleagues to study this issue using data collected from WHI participants. In the WHI, a total of 41.5 percent of the participants reported using multivitamins. By the end of the main study in 2005, 9,619 cases of breast, colorectal, endometrial, renal, bladder, stomach, lung or ovarian cancer had been reported by participants. In addition, 8,751 cardiovascular events, such as heart attack and stroke, occurred; and 9,865 deaths were reported.

Scientists did not find any significant links between multivitamin use and the likelihood of developing cancer or cardiovascular disease, or of dying. In other words, postmenopausal women who take multivitamins appear to have the same risk of most common cancers, cardiovascular disease, or dying as women who do not take multivitamin supplements.