By Shereen Jegtvig
NEW YORK (Reuters Health) - People who use multivitamins and other nutritional supplements tend to lead healthier lives overall, so taking supplements can be seen as a positive sign, suggests a new review of past research.
More than half of American adults use supplements such as multivitamins, calcium, omega-3 fatty acids, antioxidants and fiber, the researchers say. But the other things users are more likely to do - like exercise and maintaining a normal weight - are often downplayed in discussions of the value of dietary supplements.
"This evidence is based on the fact that dietary supplement users tend to be health seekers in a broader sense, that is they tend to use supplements as part of several things they do to try to improve their health," said Annette Dickinson, the study's lead author.
Dickinson is a consultant for the Council for Responsible Nutrition, a supplement industry trade group, and an adjunct professor in food science and nutrition at the University of Minnesota.
She said published articles that are critical of supplement use often add statements saying that people shouldn't use supplements as a substitute for a better diet and shouldn't think they can compensate for bad habits by using supplements.
"Those are true statements, but it implies that those are the kind of people supplement users are," Dickinson said. "We just wanted to highlight the fact that the evidence shows that that's not primarily the way they use supplements - they use them as part of an overall approach to wellness."
Several recent studies have shown no benefit from dietary supplements in preventing major illnesses like cancer and heart disease. This week, the U.S. Preventive Services Task Force, a government-backed advisory panel, said that barring known deficiencies, there's no evidence to support taking supplements and there is evidence against taking certain vitamins (see Reuters Health article of February 24, 2014, here: http://reut.rs/1fCKqCP).
In their review, Dickinson and her co-author Douglas McKay, a vice president with the Council for Responsible Nutrition, rounded up past surveys of supplement users and analyzed their traits and behaviors compared to non-users.
Women are a bit more likely than men to take supplements, the researchers report in Nutrition Journal, and supplement use increases with age for both sexes.
Supplement use has also grown over time, from 23 percent of U.S. adults using supplements in the early 1970s to 49 percent in 2007 - 2010.
In general, the researchers found that supplement users tend to be better educated: 61 percent of people with more than a high school education used them in 2006, for example, compared to 37 percent of people with less than a high school education.
Supplement users were more likely to get regular exercise, and to try to eat healthier diets, while obese people and smokers were less likely to use supplements.
Dickinson said that virtually all supplement users start with a multivitamin.
"When they get interested in supplements as a general issue, the first thing they do is take a multivitamin and then they go on taking it sometimes for a very long time - for years, decades," she said.
"But then as they learn more, they may decide to add additional things like omega-3s or calcium or vitamin D depending on their own personal risk factors and what they do or don't do in terms of their diet, and where they think improvement might be beneficial," Dickinson added.
"As has been reported previously, supplement users are more likely to report very good or excellent health, have health insurance, use alcohol moderately, not smoke cigarettes, and exercise more frequently," Paul Coates told Reuters Health in an email.
"They tend to be more health conscious and take better care of themselves," he said.
Coates is director of the Office of Dietary Supplements, which is part of the National Institutes of Health. He was not involved in the new review.
Coates said that multivitamin supplements are by far the most commonly consumed dietary supplements.
"Industry sales figures reported in the Nutrition Business Journal in 2012, showed that multivitamin/mineral supplements accounted for $5.4 billion of the total $32.5 billion in sales for all dietary supplements, or almost 17 percent of the total," he said.
Coates also said the use of a multivitamin-mineral supplement helps many people to achieve recommended intakes of a variety of nutrients they don't get from foods alone.
"But overall there are no unequivocal health benefits from taking a multivitamin-mineral supplement, either in improving health or decreasing the risk of chronic disease," he added.
Coates cautions that larger doses are often not valuable for nutritional purposes, and are not always safe.
"Except on the advice of a healthcare provider, consumers generally should not take more than recommended levels of ingredients in dietary supplements," he said.
"Remember, 'natural' doesn't always mean safe," Coates said.
Coates said people should talk to their healthcare providers about any dietary supplements they take and discuss the use of these products with them.
"Some supplements, for example, might interact adversely with medications you take or could affect a medical condition," he said.
SOURCE: http://bit.ly/1lEPuvg Nutrition Journal, online February 6, 2014.