Terra Sigillata

Dan Hurley on Medscape video

The author of Natural Causes: Death, Lies and Politics in America’s Vitamin and Herbal Supplement Industry, Dan Hurley, has a three-minute video editorial at Medscape today.

I must admit to being a little ambivalent about his message that, “Evidence-based medicine is the rallying cry of a generation of physicians. So why do so many physicians ignore the evidence when it comes to dietary supplements?”

My issue is that Hurley lumps multivitamins together with herbal supplements. Certainly, many herbal supplements have been failures in double-blind clinical trials (as I reposted earlier today) and some, like St. John’s wort, are the cause of many herb-drug interactions. But Hurley seems to cherry-pick some recent studies that suggest multivitamin supplements may do more harm than good.

Certainly, high doses of antioxidants might be useless or potentially increase mortality. But I’m not so sure that recommending a multivitamin with 100% of the recommended daily value of each constituent flies in the face of evidence-based medicine.

Hurley adequately critiques the herbal supplement industry and has received some critical acclaim for doing so, much to the chagrin of those he targets. Even Business Week, who gave his book 3.5 of 5 stars, noted that, “The book’s irate tone, however justified, grows tiresome.”

I have to admit to still having not gotten around to reading his book but I’m curious as to why he lumps simple multivitamins together with herbal supplements. The former are most often manufactured under high quality standards while the latter are more uneven in their quality control.

I welcome your comments before or after viewing his editorial.

Hat tip: anjou

Comments

  1. #1 Bill
    July 31, 2007

    Some years ago, a friend who’d worked for one told me that companies which manufacture vitamins routinely apply chemical quality control but almost never bioassay. Her reason for never taking vitamins was that a preparation of inert material is not going to do you any good no matter how pure it is.

    Do you have a sense of which vitamins that holds true for? For instance, I should imagine that for a relatively simple compound like ascorbate, chemical purity would be a fair guide to biological activity. A sterol family like “vitamin D”, on the other hand…

  2. #2 Bill
    July 31, 2007

    Oh, and hey, before I forget (again!): some time ago I made a snarky remark about Peter Duesberg’s HIV “theories” and you asked me for some facts to go with. I never did get around to it, but fortunately veteran science journalist Jon Cohen has done a very thorough job, here.

  3. #3 Abel Pharmboy
    July 31, 2007

    Very true, Bill. Standards for Vitamin A are similarly kind of dodgy now that new dietary reference intakes (DRIs) are counting “retinol activity equivalents” where 1 mcg retinol = 12 mcg β-carotene = 24 mcg α-carotene = 24 mcg β-cryptoxanthin.

    I don’t know the source right now but I’ve read somewhere that the estimated bioavailability of each constituent of most multivitamins is around 15%.

  4. #4 Jack Coupal
    August 6, 2007

    Herbal supplements and drugs are used widely outside the United States.

    In Germany, for example, St. John’s Wort is used for treating mild depression. When a study showed that it was NOT effective for major depression, some American commenters said: “See, it’s not effective for depression!”

    Taking one study result and generalizing it to the entire range of the disease spectrum is “junk science”.

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