Slate's Medical Examiner: Doubts on Supplements

New research casts doubts on the effectiveness of popular dietary supplements used to treat arthritis pain and prostate enlargement. Madeleine Brand discusses the findings with Slate contributor and Yale Medical School professor Dr. Sydney Spiesel.

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MADELEINE BRAND, host:

From NPR News, it's DAY TO DAY. The dietary supplement market is huge. People take them for all sorts of reasons: to ease pain, lose weight, even to get in a better mood. Physician and Yale Medical School Professor Dr. Sydney Spiesel writes about medical research for the online magazine Slate and he joins us this week to talk about just how safe and useful some of these supplements are. And welcome back to the program, Syd.

Dr. SYDNEY SPIESEL (Yale Medical School): Thank you.

BRAND: Now Syd, a couple of popular supplements have been tested recently. One of them is saw palmetto and that is used by some men to stop prostate enlargement, which I understand happens as men get older, their prostate enlarges and it becomes quite uncomfortable and difficult to urinate. Tell us what exactly is saw palmetto and how's it supposed to help people with prostate enlargement?

Dr. SPIESEL: Saw palmetto are the fruits of a rather beautiful plant that grows in the south in the United States. We don't know how it works, but it's used very extensively. There's a lot of sort of folklore that it's effective at decreasing symptoms of prostatic enlargement, but we really don't know how.

BRAND: And it was studied, it underwent rigorous scientific scrutiny and what were the findings?

Dr. SPIESEL: It didn't stand up very well, sadly. There might have been some very slight effect, but it really seems that it doesn't treat this condition in any very significant way.

BRAND: The other supplement that has been tested recently is a treatment for arthritis. And tell us about that supplement and how that is supposed to work.

Dr. SPIESEL: Well, that supplement is a mixture of two things, one is called glucosamine, one is called chondroitin sulphate. Both of these are somehow involved in or at least are thought to be somehow involved in cartilage and production of new cartilage. And a study that was done at the Utah School of Medicine compared these medications with giving people a placebo which had no effectiveness and giving people one of the standard treatments for osteoarthritis. This is the arthritis of wear and tear, looking at pain in the knees as an endpoint.

BRAND: And?

Dr. SPIESEL: Well, for most patients it really didn't seem to do, for people who have had mild pain it really was not much of an improvement, if any, over placebo. Interestingly, for the subset of people who had moderate to severe pain it really did seem to decrease the pain in those people. And I should say that one of my wife's doctors has a cat and she says that this cat cannot get up in the morning without a little dose of glucosamine and chondroitin sulphate.

BRAND: Are there any supplements out there that do work, that have undergone scientific scrutiny and have proved effective?

Dr. SPIESEL: Yes, and some of them to the dismay of the manufacturers were taken off the market because they proved to be effective. For example, there was something called red rice yeast that's been used as a dietary supplement in Asia for a long time. It turned out that it was actually quite effective at lowering cholesterol and the reason it was effective at lowering cholesterol is that it was the same, it produced the same active ingredient as one of the drugs that a major manufacturer of pharmaceuticals used. And so once that was shown to be true, it was said, well, this isn't a nutritional supplement anymore, this is a drug. So it was taken off the market.

BRAND: Well, that is indeed a cruel irony, that if the supplements actually do work, then they're taken away.

Dr. SPIESEL: The manufacturer's would just as soon not have them tested because if they're tested, two possibilities. It might turn out to be ineffective or it might turn out to be effective and something like red rice yeast will happen.

BRAND: Dr. Sydney Spiesel of the Yale Medical School and of slate.com, thank you very much.

Dr. SPIESEL: Thank you.

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