Long-term multivitamin use has no impact on the risk of common cancers, cardiovascular disease or overall mortality in postmenopausal women, a new study finds.
The message is simple and echoes the advice of most researchers who have looked into the effects of diet: Eat real food.
Several other studies have shown vitamin supplements to be next to worthless and in some cases harmful.
"Get nutrients from food," said study leader Marian L. Neuhouser of the Public Health Sciences Division at the Hutchinson Center. "Whole foods are better than dietary supplements. Getting a wide variety of fruits, vegetables and whole grains is particularly important."
Multivitamins because they are the most commonly used supplement in the United States, used by more than half of residents, who spend more than $20 billion on these products each year, Neuhouser said.
"To our surprise, we found that multivitamins did not lower the risk of the most common cancers and also had no impact on heart disease," she said.
The results were published in the Feb. 9 issue of the Archives of Internal Medicine.
The study was big. It assessed multivitamin use among nearly 162,000 women enrolled in the Women's Health Initiative, one of the largest U.S. prevention studies of its kind designed to address the most common causes of death, disability and impaired quality of life in postmenopausal women. The women were followed for about eight years.
Of the participants, 41.5 percent reported using multivitamins on a regular basis. Multivitamin users were more likely to be white, live in the western United States, have a lower body-mass index, be more physically active and have a college degree or higher as compared to non-users. Multivitamin users also were more likely to drink alcohol and less likely to smoke than non-users, and they reported eating more fruits and vegetables and consuming less fat than non-users.
During the eight-year study period, 9,619 cases of breast, colorectal, endometrial, renal, bladder, stomach, lung or ovarian cancer were reported, as well as 8,751 cardiovascular events and 9,865 deaths. The data showed no significant differences in risk of cancer, heart disease or death between the multivitamin users and non-users.
These findings are consistent with most previously published results regarding the lack of health benefits of multivitamins, Neuhouser said. But this study provides definitive evidence.
"The Women's Health Initiative is one of the largest studies ever done on diet and health," she said. "Because we have such a large and diverse sample size, including women from 40 sites across the nation, our results can be generalized to a healthy population."
Since the study did not include men, Neuhouser cautions that the results may not apply to them.