Respectful Insolence

Damn if PZ didn’t beat me to this one:

A federal panel concluded yesterday that there is not enough evidence to recommend for or against use of multivitamins and minerals — the popular dietary supplements taken by more than half of American adults in the hope of preventing heart disease, cancer and other chronic illnesses.

Americans spend an estimated $23 billion annually on various multivitamins and multi-mineral supplements, the 13-member panel found. One of the latest federally funded national surveys showed that 52 percent of adults reported taking multivitamins. Slightly more than a third of those surveyed said that they take these products regularly.

Several studies suggest that consumers believe that taking a multivitamin promotes health and can prevent some common diseases, but the evidence for both is “quite thin,” said the panel’s chairman, J. Michael McGinnis, senior scholar at the National Academy of Sciences’ Institute of Medicine.

That’s no big surprise, as the evidence that supplementing one’s diet with additional vitamins will do any good at all if you’re already eating a balanced diet has been shaky at best for a long time.

Indeed, the panel only found three situations the evidence indicates a clear benefit from vitamin supplementation: prevention of birth defects of the brain and spine by giving women of child-bearing age folic acid; reduction of macular degeneration by supplementation with vitamins C and E, beta carotene and the minerals zinc and copper; and lowering the risk of bone fractures in post-menopausal women through calcium and Vitamin D supplements.

In addition:

But the panel also found that multivitamins “are virtually unregulated” by the federal government. It advised Congress to expand the Food and Drug Administration’s authority and resources to require manufacturers to disclose adverse events, ensure quality production

What was most amusing was the response of the vitamin industry:

The dietary supplement industry criticized the panel for not considering less scientifically rigorous studies that point to multiple benefits from multivitamin and mineral use.

“They have done exactly what they set out to do, which is a review based solely on randomized controlled trial data, which results in a misleading picture,” said Annette Dickinson, past president of the Council for Responsible Nutrition, an industry trade association.

Damn those scientists for insisting on rigorously designed, adequately powered randomized clinical trials to answer medical questions! How dare they? What do they think this is, science? (Hmmm. I wonder why the vitamin industry would say such a thing.)

“There’s huge evidence that these products are safe,” Dickinson said.

Mrs. Dickinson, Mr. Strawman. Mr. Strawman, Mrs. Dickinson. That’s not what the panel said. The panel said that the evidence for the value of vitamin supplementation is very thin, except in a few situations. They also expressed a reasonable concern that the industry is essentially unregulated and that people may be getting more vitamins than they need, some of which can cause problems when taken in excess. Their conclusion was that, except in the cases above, there’s inadequate data to support or reject the use of vitamin supplementations.

Note also that the industry isn’t exactly disputing the actual conclusions of the panel; it’s only complaining that the panel didn’t look at less rigorous scientific studies. Sorry, Annette, but when there are decent randomized blinded clinical trials available addressing a medical question, they almost always trump less rigorous trials. The only exception is when a flaw in the RCT exists that invalidates its results. Indeed, physicians should only make decisions based on lower levels of evidence than RCTs when no good RCTs addressing a clinical question exist. If well-designed, well-powered clinical trials show a result for a question, it would have been irresponsible of the panel to put much stock in less rigorous studies that are prone to more biases and problems that RCTs.

Yep, all that sciency-ness can be frustrating.

Comments

  1. #1 sharon
    May 19, 2006

    “the evidence that supplementing one’s diet with additional vitamins will do any good at all if you’re already eating a balanced diet has been shaky at best for a long time”

    But what if you’re not eating a balanced diet? Do they help then? I mean, it’s all very well to tell people to get rid of the pills and start eating more fruit and veg, but if they won’t/can’t/don’t know how to cook (whatever their excuses are), do supplements at least help to make them slightly less unhealthy? (Before anyone asks, I don’t take any supplements – though I use to take iron sometimes during my period because I’d get anaemic from time to time – and I do eat a pretty good balanced diet with plenty of fresh veg. But I know plenty of people don’t.)

    And I’m curious about the economics of this, too. Is it more expensive to pop a couple of the pills a day or go and buy the fresh food? Does anyone know?

  2. #2 Ron
    May 19, 2006

    To answer your last question, sharon, just take a peek at the produce section in a poor-neighborhood grocery store–if they have one. Then try pricing a ‘balanced diet’ in Whole Foods. The problem is, of course, poor people can’t afford supplements either.

    I don’t defend the vitamin companies but I would defend popular wisdom that leads people to want to supplement. There is pretty good evidence that much food, including fruits and vegetables, produced in the industrial food system is deficient in key micronutrients. The supplement industry is not science-based because mainstream nutritional science is clueless on issues such as missing trace minerals and food quality.

  3. #3 Laura
    May 19, 2006

    From my understanding supplementing is better than nothing but it is always better to get the vitamins from real food because there are other nutrients in the food. I also believe that you should only take a regular multi not one from a health food store because they contain way more than you need and what your body can even absorb so its really a waste. Some of them are also high in the heavy metals and fat soluble vitamins which can be dangerous. Such as iron and vitamin A. I cannot take vitamins with iron because my levels are high enough and have been told only people who are truely anemic should take them because it is stored in the liver. I have also seen vitamins that are advertised for good skin have really high levels of Vitamin A but I have read that can be bad for your liver as well.

    I think it is probably more expensive to get the vitamins from food however the cost is worth it because of the fiber an phytonutrients you get from real fruits and veggies.

  4. #4 epador
    May 19, 2006

    Horrible Confession:

    I take generic one a day chewables cause I need SOMETHING as a placebo. Plus I like the taste. [Well I could have worse perversions…]

  5. #5 Dan R.
    May 20, 2006

    If you are going to take (or are prescribed) a supplement — make sure that its got a USP label on which indicates third party testing for truth in labeling, consistancy, and bioavailability.

    http://www.usp.org/USPVerified/

  6. #6 Nathan Myers
    May 20, 2006

    A fetish for double-blind controlled trials is no better than any other fetish.

    Controlled studies can easily be as invalid as any less expensive variety, and where a badly-constructed fully-controlled study contradicts a single-blind but well-conducted test, we’re all worse off, particularly when a federal panel ignores the latter. How do studies go wrong? Subcritical dosage, incorrect delivery, dilution of indicators, selection of subject population: the list of ways to sabotage a study — even through negligence — is endless.

    Enough money is riding on both sides of the issue to make it hard to trust any of the work without extreme scrutiny. I would be nice to know that my multi actually has in it what the label says, but I trust Twinlab to ensure that more than I do the feds. There’s enormous potential value in well-designed controlled studies of nutrient supplementation, but they don’t seem to be done much.

  7. #7 Yogi
    May 20, 2006

    I’m sorry, Nathan, I don’t see that the FDA has ANY money riding on the outcome. And, since the study is right there for people to look at, tell me what’s wrong with it. (Unless you believe that they are lying about how the study was constructed, in which case, please post your reasoning.)

    Please post the link to the “sigle-blin but well-constructed study” I think you’ll find that it wasn’t randomized, as well, which makes it very unreliable.

  8. #8 Orac
    May 20, 2006

    A fetish for double-blind controlled trials is no better than any other fetish.

    Fetish? It would seem that I gored someone’s ox.

    Controlled studies can easily be as invalid as any less expensive variety, and where a badly-constructed fully-controlled study contradicts a single-blind but well-conducted test, we’re all worse off, particularly when a federal panel ignores the latter.

    Straw man argument.

    I did not say that we should “ignore” single-blind trials, or any other trials. I simply pointed out levels of evidence and that double-blind randomized controlled studies are usually the gold standard and will trump less rigorous trials. Also note that I always mentioned well-designed trials (“rigorously designed, adequately powered randomized clinical trials” was what I said, in fact). I didn’t even really make a distinction in my piece above between single- and double-blind studies, although perhaps I should have. After all, all things being equal, a well-designed double-blind study will usually trump a similar single-blind study.

    I’m rather surprised you (or anyone) trust “big vitamin” more than you trust “big pharma” or the FDA. I trust none of them that much (but “big vitamin” and “big supplement” least of all). For one thing, more and more it’s the same companies making supplements as making pharmaceuticals. Pharmaceutical companies have discovered just how profitable selling supplements can be, better yet, without all the pesky federal regulations that govern drug sales.

  9. #9 Big Al
    May 20, 2006

    There are exceptions to that. I am taking massive amounts of V B12, as I do not absorb enough from a balanced diet, or anyother kind of diet.

  10. #10 TheProbe
    May 20, 2006

    I always get a good chuckle over those who trust Big Vitamin over Big Pharma and BigFARMa when it comes to nutrition. The chief leader of the DSHEA promotors is Orrin Hatch, who flip-flops like a flounder on the deck of a boat. While pushing DSHEA in congress, he owned stock in supplement companies, and, since 1994, according to the Center for Responsive Politics, he has received $137,000 in campaign contributions from dietary supplement producers. Supplement manufacturing is a major Utah industry.

  11. #11 Joseph Hertzlinger
    May 20, 2006

    just take a peek at the produce section in a poor-neighborhood grocery store–if they have one. Then try pricing a ‘balanced diet’ in Whole Foods.

    I don’t shop at Whole Foods, but the produce at Waldbaums is far cheaper than the processed foods.

  12. #12 Nathan Myers
    May 21, 2006

    Big Pharm vs Big Vitamin means the FDA’s role is ambiguous. When it’s Big Corporate vs. the facts, it’s easy to read the bias. Here, there’s Big Corporate vs. the facts, first, and then Big this vs. Big that. Sometimes the facts win, but that’s hard to bet on when two or more Bigs are involved.

    Orac, it’s one thing to insist “on rigorously designed, adequately powered randomized clinical trials to answer medical questions” by demanding that they be conducted. It’s entirely another to neglect to perform such trials, and thereby allow oneself to ignore what the trials’ results would have confirmed. The cheaper trials telegraph the outcome of ironclad trials not conducted, so ignoring them in such cases implements bias. Nothing’s easier than killing funding for a rigorous trial, although sabotaging a trial works almost as well, and sometimes better.

    To pretend that Principle Investigators of well-funded trials are only rarely biased, or that ordinary scrutiny leaves them no way to apply their bias, would be disingenuous. Sometimes there’s nobody more gullible than a professed skeptic.

  13. #13 Abel PharmBoy
    May 21, 2006

    For anyone under the delusion that there are no financial motivations by those in vitamin and supplement industry, just attend one of their trade shows. The marketing strategies, rhetoric, and free stuff puts to shame any Pharma exhibitors I’ve seen at basic or clinical medicine conferences. The tagline on my announcement for this natural foods meeting said, “help your customers realize products they never thought they’d need.” In fact, I’d argue that supplement retailers are as aggressive as some in Pharma marketing, but with far fewer legal restrictions on the claims that can be made.

    Dan R.: One caveat about USP’s otherwise well-intentioned efforts: their definition of “bioavailability” is notnot how much active constituent(s) get(s) into the bloodstream. Clinical bioavailability studies assess the percent of compound(s) getting into the bloodstream after oral administration relative to intravenous administration (concentration-time area under the curve (AUC) from time zero to infinity), with the AUC achieved with intravenous administration defined as 100% bioavailability – much more complicated and expensive than lab dissolution studies in synthetic gastric fluid.

    Finally, neither USP, FDA, or any independent lab confirms that a company citing the USP methodology actually uses it.

  14. #14 Orac
    May 21, 2006

    Orac, it’s one thing to insist “on rigorously designed, adequately powered randomized clinical trials to answer medical questions” by demanding that they be conducted. It’s entirely another to neglect to perform such trials, and thereby allow oneself to ignore what the trials’ results would have confirmed. The cheaper trials telegraph the outcome of ironclad trials not conducted, so ignoring them in such cases implements bias. Nothing’s easier than killing funding for a rigorous trial, although sabotaging a trial works almost as well, and sometimes better.

    To pretend that Principle Investigators of well-funded trials are only rarely biased, or that ordinary scrutiny leaves them no way to apply their bias, would be disingenuous. Sometimes there’s nobody more gullible than a professed skeptic.

    And there’s no one as good as someone who is obviously not a skeptic at constructing straw man arguments. I see not just one but two there: (1) that I said we should “ignore” lesser powered trials (I did not); and (2) that I said that there is no bias in well-funded PI’s (I never even said one thing about that one way or another). Here, let me show you again:

    I did not say that we should “ignore” single-blind trials, or any other trials. I simply pointed out levels of evidence and that double-blind randomized controlled studies are usually the gold standard and will trump less rigorous trials.

    Or, how about from the original post itself:

    …when there are decent randomized blinded clinical trials available addressing a medical question, they almost always trump less rigorous trials. The only exception is when a flaw in the RCT exists that invalidates its results. Indeed, physicians should only make decisions based on lower levels of evidence than RCTs when no good RCTs addressing a clinical question exist. [Emphasis mine]

    How you managed to interpret that as saying that we should “ignore” lesser levels of evidence, I just can’t figure out. (Perhaps it is you rather than I who have a strong bias.) I simply said that they should be given less weight than RCTs and that they shouldn’t be used as primary evidence to justify a decision if good RCTs exist. Obviously, if good RCTs don’t exist for a question, you use the data you have, realizing that it’s much weaker data. But if it’s the best you have, you go with it, knowing that better studies are needed.

    You also have to remember the purpose of big panels like the one I discussed, which is to give the best statement of the current medical consensus that is presently out there. By their very nature they are very conservative, which is as it should be because doctors will be basing treatment decisions on their recommendations for years. They did not say that vitamin supplementation isn’t good for other things. All they said is that there is inadequate evidence to conclude that it is or is not and that more studies are needed.

  15. #15 Bronze Dog
    May 21, 2006

    Classic altie tactic: Put words in the skeptic’s mouth and hope no one notices.

  16. #16 JavaElemental
    May 22, 2006

    What about MSM w/ Glucosamine (sp?)? I started taking that about a year ago, for my arthritic knees, on the advice of some friends, and it really has done wonders. I’ve heard of a study or two that supported using MSM w/ Glucosamine for arthritis and joint health.

  17. #17 wheels
    May 22, 2006

    Damn those scientists for insisting on rigorously designed, adequately powered randomized clinical trials to answer medical questions! How dare they? What do they think this is, science?

    That reminds me of my last trip to Great Britain … I became violently ill a couple hours after arriving in London. The next morning, I got to a doctor who asked about my symptoms, then gave me a prescription and said I had gastroenteritis. When I asked if he would be doing any tests, his response was, “You Americans and your evidence-based medicine!”

  18. #18 Nathan Myers
    May 24, 2006

    “By their very nature they are very conservative”

    Bias is bias. An honest skeptic distrusts speculation wherever he finds it, whether promoted by quacks or by the FDA. Reflexive skepticism shades insensibly into toadyism. Orac, your strawman filter finds strawmen wherever you look. Generally it just leads you to miss the point. You would learn more if you would read more carefully. Not everything posted is meant as a direct answer to what you wrote.

    Nobody here has spoken up in favor of Big Vitamin producers. The original article, though, ridiculed a complaint: “a review based solely on randomized controlled trial data … results in a misleading picture”. Regardless of its source, it is a correct statement. That ridicule really is equivalent, despite your protestations, to arguing that other sound evidence should be ignored — even where no “randomized, controlled trial” exists to contradict it. That was the basis for my original criticism.

    Should people in northern climates get vitamin D supplements in winter? Until definitive trials demonstrate otherwise, obviously yes. Should people eat raw food frequently, even without definitive proof that it’s important? We evolved eating nothing but raw food, and it’s cheap, easy, and tasty (“an apple a day…”), so yes also. Such recommendations aren’t strictly scientific (yet), but they’re sound policy nonetheless. Medicine isn’t science, it’s just a user of science.

  19. #19 Bronze Dog
    May 24, 2006

    “a review based solely on randomized controlled trial data … results in a misleading picture”. Regardless of its source, it is a correct statement.

    There’s so much wrong with that. How could it be misleading? This touches heavily on a certain troll’s ignorance of how science works.

    That ridicule really is equivalent, despite your protestations, to arguing that other sound evidence should be ignored — even where no “randomized, controlled trial” exists to contradict it. That was the basis for my original criticism.

    Pay attention to what Orac types. Don’t put words in his mouth. That’s what your “criticism” seems to be: Putting words in Orac’s mouth and complaining about what you told him he said.

    Should people in northern climates get vitamin D supplements in winter? Until definitive trials demonstrate otherwise, obviously yes. Should people eat raw food frequently, even without definitive proof that it’s important? We evolved eating nothing but raw food, and it’s cheap, easy, and tasty (“an apple a day…”), so yes also. Such recommendations aren’t strictly scientific (yet), but they’re sound policy nonetheless. Medicine isn’t science, it’s just a user of science.

    I question your comment on raw food. Natural isn’t necessarily better. Might want to ask all the people who’ve wound up with trichinosis, or however you spell it.

    If it isn’t scientific, it’s not sound. You might be able to make an argument from cogency if your premises are reasonable, but not soundness.

  20. #20 Nathan Myers
    May 24, 2006

    To ridicule the quote does imply what I criticized, unless he specifically excludes it. His example, however, only indicated the case where a controlled trial actually exists to contradict other evidence; he leaves the remaining cases unaddressed. Most likely he was just being sloppy, but sloppiness and ridicule go together badly. Such sloppiness deserves criticism. An honest skeptic welcomes corrections to sloppiness.

    If you want more strawman accusations (which seem ridiculously welcome here), nobody said “natural is necessarily better”. I don’t know who “a certain troll” is, and don’t much care. I know perfectly well how science is supposed to operate, and I’ve seen more than enough badly conducted science. But, again, science isn’t the same as medicine, and to confuse them would be sloppy. I don’t like sloppiness any better than bias.

  21. #21 Nathan Myers
    May 24, 2006

    … but toadyism is worse than either.

  22. #22 Orac
    May 24, 2006

    “By their very nature they are very conservative”

    Bias is bias.

    By “conservative,” I mean that they want lots of data to support what they say, that they won’t put recommendations in their final statement. Are you suggesting that they shouldn’t operate that way? Remember, these panels are designed to present a consensus statement that is based on the soundest evidence that they can find, and their recommendations are used as guidelines by physicians all over the U.S.

    An honest skeptic distrusts speculation wherever he finds it, whether promoted by quacks or by the FDA. Reflexive skepticism shades insensibly into toadyism.

    Don’t presume to lecture me on what an “honest skeptic” does. An “honest skeptic” doesn’t use straw man arguments, as you have, nor does he throw around ad hominem accusations of toadyism. And what the FDA said in this statement was not speculation.

    That ridicule really is equivalent, despite your protestations, to arguing that other sound evidence should be ignored — even where no “randomized, controlled trial” exists to contradict it.

    Bullshit.

    I’m getting really sick of your straw men arguments. I repeat once again: Nowhere did I say that “sound evidence should be ignored” or anything similar. I merely pointed out that the vitamin manufacturers were arguing for the use of evidence of much poorer quality than RCTs because that evidence supports a position that benefits their financial interests, namely that using vitamin supplements is beneficial for things other than the few situations the consensus panel agreed on.

    That’s enough for today. I was up all last night operating and had a particularly bad day afterward–and I get to be on call again through Memorial Day. I’m a bit cranky and not particularly interested in jousting with you right now, particularly after your straw men arguments and accusations of toadyism. They would be enough to annoy me on their own, but combine them with my a lack of sleep, and I really have no more patience for your antics tonight.

  23. #23 Nathan Myers
    May 25, 2006

    Orac, if you can’t be bothered to read carefully, why keep a blog at all? Nobody’s conspiring to assault you with strawman arguments. Anyway, aren’t there any other weak argument forms you’d like to invoke, scattershot?

    You were sloppy in ridiculing a statement that, as stated, didn’t deserve ridicule (even if the people involved did deserve it). Be an adult, admit it, and move on. I forgive you your wild accusations because I recognize you’re not really paying attention. For the record, though, I didn’t accuse you of toadyism; it’s just the most disgusting of the biases that pretend to skepticism.

  24. #24 Orac
    May 25, 2006

    Orac, if you can’t be bothered to read carefully, why keep a blog at all? Nobody’s conspiring to assault you with strawman arguments.

    You may not be “conspiring to assault me with straw men arguments,” but you are using them, as I have pointed out several times.

    Be an adult, admit it, and move on.

    Pot. Kettle. Black.

    There’s nothing for me to admit, and, quite frankly, after your last round of straw men and accusing other commenters in this post of toadyism, as of this morning, I have moved on. Good day.

  25. #25 Kevin T. Keith
    May 25, 2006

    “You Americans and your evidence-based medicine!”

    Funny. But you know, of course, that “evidence-based medicine” is a term of art with a specific meaning. It is the current trend in US medicine for laboratory confirmation of diagnoses whenever possible, and a de-emphasizing of traditional, empirical methods in favor of clinical-trial-based optimized treatment protocols. I presume the doctor simply meant that he felt his keenly-honed clinical judgment was sufficient, rather than demanding a lab workup for an ordinary tummyache.

    I’m not sure I agree, but I don’t think it’s in the same league with the pharma rep’s demand for non-rigorous clinical trials.

  26. #26 Nathan Myers
    May 26, 2006

    I’m sorry, I didn’t realize this was the Rush channel. My mistake.

  27. #27 epador
    May 31, 2006

    NM: tiresome troll not spanked hard enough by Orac.
    Orac: sleep deprived but still can deliver a licking and keep on ticking

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