Taking dietary supplements? It may be too much

Sat Oct 8, 2011 4:02pm EDT

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(Reuters) - People who take dietary supplements to boost their intake of minerals may actually be getting too much of a good thing -- and even risk serious problems.

According to astudy published in The American Journal of Clinical Nutrition, people who take dietary supplements also tend to get more nutrients from their food than those who don't take supplements -- suggesting that vitamins may be taken by the people who need them least.

In some cases, supplement users may actually be overloading on minerals, such as iron, that can cause potentially serious health problems, researchers said.

"People need to choose supplements to help meet, but not exceed, the recommended daily intake levels," said Regan Bailey, a nutrition research at the National Institutes of Health, who led the study.

Bailey and her colleagues used dietary surveys to assess mineral intake among 8,860 men and women who participated in a major government health survey between 2003 and 2006.

Men and women who reported using dietary supplements containing eight important minerals -- calcium, iron, magnesium, zinc, phosphorus, copper, potassium and selenium -- were much less likely to be getting inadequate amounts of those minerals from the foods they ate than were people who said they didn't take supplements, the study found.

The link was strongest for women, who are more likely than men to take supplements.

Supplement users, in turn, tended to eat better and live healthier lifestyles than non-users, Bailey noted.

The NIH team also found that calcium intake often fell below recommended levels, even among professed supplement users.

Roughly a quarter of supplement users, and 71 percent of nonusers, did not receive the recommended daily amount of calcium -- 800 to 1,000 milligrams a day for men over age 51 and 1,000 to 1,200 mg per day for women of the same age. Calcium is necessary for the healthy formation of bone.

Older people were much more likely to fall short of their daily calcium requirements -- but also to exceed them.

That's because people tend to use more supplements as they age, which helps explain why nearly 16 percent of women between the ages of 51 and 70 reported daily calcium intakes that exceeded the recommended upper limit. Too much supplemental calcium has been linked to kidney stones.

Supplement users were also more likely to boost their intake of magnesium and zinc above recommended upper limits, although the health consequences, if any, of consuming too much of those minerals are unknown.

"We always would hope that the people who are taking dietary supplements are the ones who need it the most, but it doesn't seem to be true," said Cheryl Rock, a nutrition researcher at the University of California, San Diego, adding that the results were not surprising.

When it comes to over consumption, Rock added: "We have been telling people clinically for years that the daily value cut point is not your minimum requirement. Having a dietary assessment is definitely a good idea." Source: bit.ly/nAkGAU

(Reporting from New York by Adam Marcus at Reuters Health; editing by Elaine Lies)

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Comments (3)
TimBickerton wrote:
“Too much supplemental calcium has been linked to kidney stones.”

My experience with kidney stones three years ago kicked off my education into the fascinating world of calcium. What’s the best source of calcium? Milk, cheese and other dairy products, right? At least that’s the message that gets drilled into us in kindergarten and beyond. Thanks, National Dairy Council! But if you listen to what science has to say on the subject of calcium, you will soon be re-thinking that position.

Oct 08, 2011 3:09pm EDT  --  Report as abuse
Raelyn wrote:
Bread, breakfast cereals, almost every food on the market adds vitamins well over the daily requirements, which would be OK except that they do not add all the vitamins, only the most common. I did a lot of research and made myself a list of vitamins and supplements that I thought I needed, had it approved by my doctor, only to find many (of dubious quality) are added to almost every grocery item that I buy. We need to be aware of this overuse of a few done to make a food appear more nutritious while neglecting others that we also need and wouldn’t otherwise get.

Oct 09, 2011 5:42pm EDT  --  Report as abuse
always.pbraun wrote:
I’ve read that supplements are unnecessary in some people and are often taken in excess. Do we really need to be taking more vitamins? I think that the easiest way to learn more about your individual body chemistry is to just get your blood tested. I’ve found that the easiest way to do this is to use Inside Tracker, which can save you a whole lot of money on multivitamins and supplements, and might also spare you from the potentially harmful health effects of supplement overdose. If anyone is interested, here’s a link: http://www.insidetracker.com/

Oct 12, 2011 3:39pm EDT  --  Report as abuse
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