Oct 11 Women taking multivitamins don't live
longer than those who get their nutrients from food alone,
according to a U.S. study that found they in fact appear to have
slightly higher death rates.
About half of adult U.S. residents take dietary supplements,
and the industry now boasts of annual sales as high as $20
billion. Yet research suggests that some of the largely
unregulated substances, such as vitamins A and E, could be
harmful in high doses, according to an editorial published with
the study in the Archives of Internal Medicine.
"There is very little evidence showing that common dietary
supplements would be beneficial in prevention of major chronic
diseases," said Jaakko Mursu of the University of Minnesota in
Minneapolis, who worked on the study.
"Unless you are deficient, there is hardly any reason to
take them," he told Reuters Health.
Mursu and his colleagues used data from nearly 39,000 older
women who participated in the Iowa Women's Health Study and
filled out questionnaires starting in 1986.
The survey asked about use of multivitamins, vitamins A, C,
D and E as well as beta-carotene, B vitamins and minerals such
as calcium, copper, magnesium, selenium and zinc.
During the study, supplements became increasingly popular.
Between 1986 and 2004, the proportion of women who said they
took one or more jumped from 63 percent to 85 percent.
Only calcium supplements were linked to a lower risk of
death over 19 years of follow-up, with 37 percent of users dying
compared to 43 percent of non users. That link held up even
after considering that women taking supplements had a healthier
lifestyle than the rest.
By contrast, women taking other supplements did not live
longer. For instance, 41 percent of multivitamin users died
versus 40 percent of non-users -- and the gap became even wider
when adjusting the numbers based on health problems like
diabetes, high blood pressure and overweight in the two groups.
Mursu said he expects that his findings will be true for men
as well, adding that they jib with earlier research hinting that
dietary supplements do little good in Western countries where
vitamin deficiency is not common.
One possible exception is vitamin D, which one recent study
suggests may help women live a little longer.
Mursu also cautioned that his study doesn't prove
supplements cause harm.
"I would rather conclude that there is no evidence for
benefits," he said.
The 2010 U.S. dietary guidelines recommend getting nutrients
from food, not supplements. However, women of reproductive age
are advised to get extra folic acid and those who are pregnant
may want to take iron supplements if their doctor suggests it.
The guidelines also urge people 50 and older to get extra
vitamin B12 from fortified foods or supplements.
Duffy MacKay of the Council for Responsible Nutrition, a
trade association representing manufacturers and ingredient
suppliers of dietary supplements, disagreed with the
researchers' conclusion that doctors should only recommend
supplements to people with deficiencies.
He added that in the case of iron, women on high doses may
have underlying conditions that could explain their higher death
While Mursu acknowledged that shortcoming, he said it is
unlikely to be relevant for multivitamins, which usually aren't
prescribed by a doctor.
Short of getting sick, he added that it's hard to know if
you are getting enough vitamins and minerals, and that screening
everybody would be prohibitively expensive.
"Include as many vegetables and as much fruit as you can,"
he said, by way of advice. "There is hardly any reason to limit
those, and they contain a whole lot of vitamins and minerals."
(Reporting from New York by Frederik Joelving at Reuters
Health, editing by Elaine Lies)