Will taking multivitamins protect you from dying of cancer or heart disease? The answer is no, according to new research.
In a study of more than 180,000 people, scientists saw the same number of deaths from cancer and heart disease among multivitamin-takers and those who did not take the supplements.
"People need to understand that just taking these multivitamins is not sufficient to prevent disease," said Jennifer Hsiang-Ling Lin, assistant professor of medicine at Brigham and Women's Hospital in Boston, who did not work on the study.
Multiple past studies have shown no link between multivitamins and reduced risk of cancer or heart disease. Other recent research couldn't prove that multivitamins protect against diabetes, either.
Some small studies in the past have shown that specific vitamins, not multivitamins, may be protective against heart disease or cancer later in life. However these studies looked at undernourished people, not generally healthy adults like the U.S. population, said co-author Song-Yi Park, assistant professor of epidemiology at University of Hawaii Cancer Center in Honolulu.
On its website, the U.S. National Institutes of Health advise that doctors should prescribe multivitamins only "for patients who need extra vitamins, who cannot eat enough food to obtain the required vitamins, or who cannot receive the full benefit of the vitamins contained in the food they eat."
But more than half of U.S. adults choose to take multivitamins, according to Lin.
Many do because they think it will prevent chronic disease, said Ross Prentice, director of the Fred Hutchinson Cancer Research Center at the University of Washington in Seattle, who also did not work on the new study.
Altogether, Park's team looked at the vitamin-popping habits of more than 82,000 men and nearly 100,000 women, who were an average of 60 years old. Then they tracked how many died, and the causes, over the next 11 years.
Overall, about six in 100 multivitamin users and non-users died from heart disease. Cancer claimed about five in 100 from both groups, and four in 100 died from other causes. In total, almost 29,000 people died in the 11 years of follow-up.
The multivitamins didn't seem to protect users from cancer in general, or from cancers of the lung, colon, rectum, prostate, or breast.
Each year in the U.S. about 616,000 people die from heart disease and about 560,000 die from cancer, according to the American Cancer Society.
The researchers did not find that taking multivitamins hurts anyone, Lin noted.
However, they can be expensive. According to Consumer Reports, Americans spent almost $4.7 billion on multivitamins in 2008. Depending on the type, supplements range from $3 to $16 a month.
This study could not prove that multivitamins do or don't affect people's risks for heart disease and cancer. A large clinical trial — one that can show cause and effect, if it exists — is underway but the results aren't available yet.
Past studies have mostly involved Caucasians, Lin said. The current one, published in the American Journal of Epidemiology, included large numbers of Latino and Japanese-American people. This shows that the lack of association held up for different racial groups as well, she said.
The best way to reduce the risk of cancer and heart disease, according to Lin? Exercise and eat a healthy diet.