By Andrew M. Seaman
NEW YORK (Reuters Health) - There is not enough evidence to recommend that people take multivitamins or single or paired nutrients to prevent cancer or heart disease, according to a government-backed panel.
But there is enough evidence to recommend that people do not take beta-carotene or vitamin E to prevent those conditions, the U.S. Preventive Services Task Force (USPSTF) said.
The final recommendations, published in the Annals of Internal Medicine, largely mirror draft guidelines that were released by the USPSTF in November (see Reuters Health story of November 11, 2013 here: http://reut.rs/1e1ilDe.) They do not apply to people with known vitamin deficiencies or chronic illnesses.
"Because so much money is spent and so many people think they're doing themselves good by taking multivitamins, we really do need research to find out if that is the case," Dr. Virginia Moyer, who chairs the USPSTF, told Reuters Health.
Moyer is also the vice president for maintenance of certification and quality at the American Board of Pediatrics in Chapel Hill, North Carolina.
While generally calling for more research on vitamins, the USPSTF concluded there is enough evidence that beta-carotene increases the risk of lung cancer among those who are already more likely to develop it, such as smokers.
After reviewing six trials, researchers who compiled a summary of available evidence for the panel found there were few or no harms linked to taking vitamin E, but it also did not reduce the risk of heart disease or cancer.
Duffy MacKay agreed that the new recommendations are a call for additional research - especially research that takes into account the nuances of nutrition.
He is senior vice president for scientific and regulatory affairs at the Council for Responsible Nutrition, a trade association in Washington, D.C. that represents dietary supplement manufacturers and ingredient suppliers.
For example, MacKay pointed out that it's difficult to compare the effectiveness of multivitamins or nutrients in trials similar to those that evaluate traditional drugs, because all people usually get some of the vitamins or nutrients through their diet.
But he said his organization has compiled research that shows there are meaningful nutrient gaps in the general population.
"A significant portion of Americans are falling short in essential nutrients," MacKay told Reuters Health. "Most Americans will benefit from a multivitamin as an insurance policy."
He said it's important for people to talk with their health care practitioner about the products that are right for them.
Moyer said the USPSTF reevaluates recommendations about every five years, but there are some exceptions if a topic is prioritized.
In general, she said people should be getting the vitamins and nutrients they need from their diet.
"It's probably not the individual vitamins or minerals or anything else," she said. "It's what you get from the whole of a balanced diet."
SOURCE: http://bit.ly/SQRXAa Annals of Internal Medicine, online February 24, 2014.