How Effective Are Multi-Vitamins?

Those "one-a-day" pills might not be worth the money. A new study suggests that popular multi-vitamins may not actually improve your health.

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MADELEINE BRAND, host:

This is Day to Day from NPR News. I'm Madeleine Brand. A new study finds that popping a multivitamin pill everyday will not prevent cancer or heart disease. NPR's Allison Aubrey joins me now to explain the study. And Allison, this was a long-term research project involving lots and lots of people. What did the scientists do?

ALLISON AUBREY: Well, they looked at information collected from, as you say, lots and lots of people; that, in this case, was 160,000 women. These were women enrolled in something called the Women's Health Initiative. These are large clinical trials that went on for 15 years. Women, when they entered the study, were between the ages of 50 and 79, and about 40 percent of them used multivitamins during the study. So, what researchers have done now is they've looked back, and they have looked at rates of everything from breast cancer to stomach cancer, ovarian, kidney cancers, as well as heart disease, things that include, you know, heart attacks and strokes, and they have found that women taking the multivitamins were no more or less likely to develop these cancers or heart disease compared to those not taking a multivitamin.

BRAND: And is this a shocking finding, or is this something that other scientists have already discovered?

AUBREY: Well, I actually interviewed the lead researcher yesterday afternoon, and it turns out that she wasn't very surprised, just because there been other studies done on multivitamins and you don't see big changes in terms of these outcomes, these health outcomes. If there are things that these vitamins do in terms of health that aren't measurable, we don't know about them. But in terms of preventing disease or promoting disease, it seems there is - they don't do either.

BRAND: Well, I imagine a lot of Americans do take a multivitamin every day or some kind of supplement. So, should they keep doing it, or should they just stop? Could there be benefits to taking it still?

AUBREY: Yeah, well, about a third of American adults take some kind of multivitamin on a regular basis. And I mean, I think that this is where it gets really tricky and experts just don't agree. It depends on who you ask. So, one thing that we can say is that certain vitamins included in a multivitamin are known to bring certain benefits. For instance, folic acid for women of childbearing age is known to prevent birth defects. Calcium for bones and, increasingly, vitamin D is recommended for everyone from children to old adults. So, if you break it down, there are some specific vitamins with some known benefits. It's just that when we look at a multi, we don't see any clear benefit or, I should point out, risk.

BRAND: Well, what about just basically eating your fruits and vegetables and eating a balanced diet? Is that a better way to go?

AUBREY: That is the conclusion of some of the researchers involved in this project, that for women, particularly in this age group - and we should be specific here that we can't necessarily generalize the outcome of the study to the entire population. I should repeat that these were women between 50 and 79, older women, postmenopausal women, when the study began. And for them, there is no clear risk or benefit - difference in risk or benefit for developing these diseases down the line. But I would say that most experts come down on, if you have a healthy diet, you probably are getting all of the nutrients you need.

BRAND: NPR's Allison Aubrey, talking about a new study published in the Archives of Internal Medicine that says multivitamins do not ward off cancer or heart disease. Allison, thank you.

AUBREY: Thank you, Madeleine.

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