Skepticism

Episode 2 of Curiosity Aroused: Vitamins

As ever, the show can be found at curiosityaroused.com, via RSS, or on iTunes in the culture section.

Show notes after the jump!

Show Notes courtesy Amanda Leinbaugh

Vitamin supplements are so popular that last year in the US there were $23 billion of sales. This number is only growing as more and more people look to vitamins as a relatively cheap way to improve their health and prevent disease. They are supposed to offer a wealth of health benefits- from cancer prevention to healthier hair. The CDC even recommends that *all* women who can become pregnant take folic acid (which is a B vitamin) supplements in order to lower the risk of fetal developmental problems

CDC report – http://cdc.confex.com/cdc/pcs2007/techprogram/P13424.HTM

If we take vitamins in pill form, will we actually get the purported benefits? Will they just be a waste that we pee out? Or could they even possibly harm us?

-Harriet Hall’s “Should I Take a Multivitamin?” article http://www.sciencebasedmedicine.org/?p=160

FDA regulation of supplements

“Under the Dietary Supplement Health and Education Act of 1994 (DSHEA), the dietary supplement manufacturer is responsible for ensuring that a dietary supplement is safe before it is marketed. FDA is responsible for taking action against any unsafe dietary supplement product after it reaches the market. Generally, manufacturers do not need to register their products with FDA nor get FDA approval before producing or selling dietary supplements.”

FDA supplement site: http://www.fda.gov/food/DietarySupplements/default.htm

There are two types of vitamins: water soluble and fat soluble. The B vitamins and vitamin C are water soluble, meaning we can rid ourselves of any excess by peeing them out. Vitamins A, D, E, and K are all fat soluble which means we can store them in our bodies for later use and can accumulate excessive amounts if our intake is too high. It does take a concerted effort to overdose on vitamins but it is possible especially with concentrated single-vitamin supplements.

-On dissonance of the effectiveness of vitamins contrasted with how popular they are http://www.sciencebasedmedicine.org/?p=285

Common wisdom ascribes the same benefits of eating vitamin-rich food with taking vitamin supplements. However, most scientific studies have found no benefit or even harmful effects from taking vitamin supplements.

In 2008 there was a meta-analysis done on studies of vitamin supplements. 67 clinical studies were used, with a total of over 200,000 total participants. 21 of the trails studied vitamin effects on disease and the rest of the trials were performed on healthy individuals. The meta-analysis found that taking antioxidant supplements may actually have a detrimental effect on health. Vitamin C supplements were found to have no positive or negative effects on health.

In other studies, vitamin A supplementation has been linked to increased rate of hip fracture in post-menopausal women. High intake of vitamin A can also cause problems for fetal development.

-Link to PDF of the meta analysis

http://www3.interscience.wiley.com/homepages/106568753/CD007176.pdf

Yet with all this possibility for harm or just expensive pee, a lot of people still take vitamins. Many do it to make up for a poor diet. There is a lot of evidence out there that a diet made up of foods rich in vitamins and other nutrients definitely has a positive impact on health. Think of that in contrast to the lack of evidence that vitamin supplements do us any good and the findings that they can even cause harm in some cases. 23 billion dollars a year on pills that probably don’t do anything and can possibly hurt you. It’s something to think about the next time you feel guilty about your diet and try to assuage your guilt by reaching for the multivitamins.

Special thanks to Maria Walters, Amanda Leinbraugh, Edith Applesauce, and today’s band March of Dimes, who provided all the music. You can hear more at http://www.myspace.com/marchofdimesleeds, and their brand new EP From Those Who Were There will be available in April from iTunes, Spotify, 7 Digital, and Amazon.

Tune in to our next episode where we ask some gossipy questions about historical queens. Who was a virgin? Who got intimate with a horse? You know you want to know.

You can find more CuriosityAroused on iTunes or at curiosityaroused.com. Thanks for listening.

Rebecca Watson

Rebecca leads a team of skeptical female activists at Skepchick.org. She travels around the world delivering entertaining talks on science, atheism, feminism, and skepticism. There is currently an asteroid orbiting the sun with her name on it. You can follow her every fascinating move on Twitter or on Google+.

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13 Comments

  1. I totally agree that too many people take vitamins because they think they are a magical medical panacea. I’ve personally seen people who are, ironically, what I’d call “health nuts” taking fists full of vitamins a day, simply in the mistaken belief that they will help ward off disease.

    Personally, I take two multi-vitamins a day, but only on the advice of my doctor and only because I had bariatric surgery and need to be on a low calorie, high protein diet for the rest of my life, so I can’t always get all the vitamins I need from diet alone.

    I think that all supplements should be regulated by the FDA (or similar agency, depending on where you live) and go through the same approval process as currently regulated medicines.

  2. Do you have any links to studies on Vitamin D, or did I miss that?
    Living in northern Alberta, apparently we don’t get any from the Sun in the winter, so I’ve been taking a Vit D supplement.

  3. I used to take multivitamins, but I stopped taking them. I used to forget them anyway.

    But I can’t help but notice that every time I get a checkup, I always get asked about calcium supplements. This is even before anyone asks me about dairy intake. I started taking them, but I do wonder whether I need to. Any evidence for calcium and iron?

  4. @noophy: I can ask Amanda if she has one handy!

    @mikerattlesnake: Yep! I’ve made myself a little database of bands so that for each episode I can trawl through and find music that fits the feel. Send some links to rebecca at skepchick.org

    @infinitemonkey: Biweekly for the moment but eventually I’d love for it to be weekly. I just want to start a bit slower so that we can keep quality high.

  5. I wonder how many people actually need dietary supplements. They won’t cure cancer or the common cold, but they are pretty good at curing and preventing specific deficiencies. I used to take a multivitamin because I just do not like most vegetables, and it’s just not a realistic goal for me to eat enough of them every day. I’ve always known that supplements aren’t as good as the real thing, but I thought they’d be better than nothing, since the real thing just isn’t an option. Then I heard about the study showing no benefit, so I stopped taking them. A few months later, I developed iron deficiency anemia. So now I take a daily iron supplement because it’s almost impossible for me to get enough iron from the food I eat.

  6. The basic information about vitamin D:
    Vit. D deficiency is fairly common.
    Vit. D deficiency has lots of adverse effects.
    Too much vit D also has adverse effects.
    You can’t get too much vit D from exposure to sun, but you can get too much by taking pills.

    (All this information is from popular science articles via my memory.)

    Conclusion: ask your doctor if/how much to take.

    Conclusion 2: Or make sure you get sufficient UV exposure every day via UV lamps during winter.

    Conclusion 3: New product niche: shower stalls with UV lamps. Get a suitable safe measured UV exposure every day while you shower – just set the dial for however many seconds when you start showering.

  7. Interesting. I’m a fence sitter when I comes to vitamins. I don’t believe that I really need most of them and I know an overdose can really harm you for some of them. However, I also take a high-dose b12 supplement every single night (sometimes doubling up on it or also taking a multi-vitamin). I can say this. As someone who has had several severe nutritional deficiencies due to a chronic disease I have managed to pull my b12 levels up to the bottom end of normal with just the supplement. I’ve also found that an iron enriched multi to help with my occasional anemia. So taking supplements to specially target (medically validated) low levels of those minerals seems to work. Taking them to do other stuff like make for shiny hair or whiter teeth, I’m not so sure about.

  8. Never took vitamins until I saw this meta-meta-analysis by informationisbeautiful.net

    http://www.informationisbeautiful.net/2010/snakeoil-scientific-evidence-for-health-supplements/

    This is a visualization of supplement clinical trial for various health benefits.

    It is based on this spreadsheet:

    http://spreadsheets.google.com/ccc?key=0Aqe2P9sYhZ2ndFRKaU1FaWVvOEJiV2NwZ0JHck12X1E&hl=en_GB

    Which has links to the published peer-reviewed efficacy studies like this:

    http://www.ncbi.nlm.nih.gov/pubmed/18034918

    So most supplement claims are false or unsupported but some, like VitD, have a basis on efficacy trials.

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