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.
