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Multivitamins Have No Effect On Cancer, Heart Disease

Posted on: Tuesday, 10 February 2009, 06:50 CST

Long-term multivitamin use has no impact on the risk of common cancers, cardiovascular disease, or overall mortality in postmenopausal women, according to a new study led by researchers at Fred Hutchinson Cancer Research Center.

The study results were published in the latest issue of the Archives of Internal Medicine.

Researchers narrowed their focus on the effects of multivitamins because they are the most commonly used supplement.

"Dietary supplements are used by more than half of all Americans, who spend more than $20 billion on these products each year. However, scientific data are lacking on the long-term health benefits of supplements," said lead author Marian L. Neuhouser, Ph.D.

Neuhouser is an associate member of the Public Health Sciences Division at the Hutchinson Center.

"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.

Researchers studied 162,000 women for eight years, who were enrolled in the Women's Health Initiative.

The WHI is 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.

Nearly half of the study participants reported using multivitamins on a regular basis. Many 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.

Researchers discovered 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 study found no significant differences in risk of cancer, heart disease or death between the multivitamin users and non-users.

"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 wrote.

Co-author Dr. JoAnn Manson said despite the disappointing results, the research doesn't mean multivitamins are useless for people.

She notes that the data are observational, not the most rigorous kind of scientific research. Also, it's not clear if taking vitamins might help prevent cancers that take many years to develop, said Manson, chief of preventive medicine at Harvard's Brigham & Women's Hospital.

She said multivitamins may still be useful "as a form of insurance" for people with poor eating habits.

So what does the study mean for women who want to make sure they're getting optimal nutrition?

"Get nutrients from food," Neuhouser said. "Whole foods are better than dietary supplements. Getting a wide variety of fruits, vegetables and whole grains is particularly important."

The WHI study authors acknowledge the potential limitations of their study, and caution against extrapolating their results to the general public.

For example, the women participating in the study were well-educated and had better health habits. Approximately 40 percent had a college degree or higher, and at least 80 percent finished high school.

"What this paper shows is that multivitamin use just doesn't seem to make that much of a difference in this population," says Dr. Wassertheil-Smoller. "It confers no additional benefit but it also does no harm."

Yet, Alice Lichtenstein, a Tufts University nutrition professor who was not involved in the research, said the study is important because it involved so many women.

"All the evidence keeps pointing in the same direction," Lichtenstein said.

Eric Jacobs, an American Cancer Society epidemiologist, said while his group doesn't advise vitamins to prevent cancer, it does recommend maintaining a healthy weight and eating at least five servings of fruits and vegetables daily while limiting red meat.

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On the Net:

• Fred Hutchinson Cancer Research Center
• Archives of Internal Medicine
• Women's Health Initiative
• Brigham & Women's Hospital

Source: redOrbit Staff & Wire Reports

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