Multivitamins Offer No Protection Against Cancer and Heart Disease

As many as half of American adults take multivitamin and mineral supplements on a regular basis, spending billions of dollars in hopes of improving and maintaining their health. Expert recommendations regarding supplement use as well as the strength of evidence supporting these guidelines vary widely. Multivitamins are intended to supplement human diets with vitamins, dietary minerals and other nutritional elements.

Prior evidence has suggested that vitamin rich diets may protect against cancer and heart disease, prompting keen interest among researchers to find nutritional elements that may prevent these illnesses. The latest study, published in the Archives of Internal Medicine, is also the largest of study of multivitamin use in older women. The eight-year study of 161,808 postmenopausal women revealed that multivitamins did nothing to prevent common cancers or heart disease. The data came from the Women's Health Initiative, a long-term women's health study. These finding coincide with recent vitamin studies among men.

About 42 percent of the women, ages 50 and older, participating in the study reported regular use of multivitamins. After eight years, the number of both vitamin users and non-users who developed common cancers and cardiovascular problems were found to be about equal. Adjusting for factors such as the age, race, body mass index, alcohol use, and smoking had no impact on the results. A total of 9,619 cases of cancer occurred, including breast, lung, ovarian, colorectal and stomach cancers while 8,751 women developed cardiovascular conditions that included heart attacks and strokes. The number of women who died was 9,865.

Marian Neuhouser of the Fred Hutchinson Cancer Research Center in Seattle and the study's lead author advised, “Get nutrients from food. Whole foods are better than dietary supplements. Getting a wide variety of fruits, vegetables, and whole grains is particularly important.”

Dr. JoAnn Manson, chief of preventive medicine at Harvard's Brigham & Women's Hospital and study co-author noted that even though the results were disappointing, the findings to not render multivitamins useless. She also pointed out that the study was only observational, and that it remains unknown if the use of vitamins might help prevent slow developing cancers. In addition, it should be noted that because the study only included postmenopausal women, it is not known if the study findings apply to other groups of people.

In a statement, Andrew Shao, Ph.D., vice president for scientific and regulatory affairs at the Council of Responsible Nutrition, sums it up in stating, “Multivitamins, like all other dietary supplements, are meant to be used as part of an overall healthy lifestyle; they are not intended to be magic bullets that will assure the prevention of chronic diseases, like cancer.” In addition, he noted that for those people who do not get recommended amounts of various essential nutrients from their diets might benefit from consistently taking a multivitamin over the long term to help fill nutrient gaps.