Surprising Study: Put Down the Vitamins & Free the Free Radicals

By Eliza Strickland | May 12, 2009 10:36 am

marathonIn recent years, antioxidants have been touted as a secret to healthy living: The molecules bind to reactive oxygen compounds called “free radicals” that are known to damage the body’s tissues. The amount of oxidative damage increases with age, and according to one theory of aging it is a major cause of the body’s decline [The New York Times]. But a new study examined the effects of the antioxidant vitamins C and E when combined with an exercise regimen, and found a considerably more complicated story. The researchers found that free radicals may be beneficial in small doses, and may even help protect against diabetes. And mopping them up with antioxidants may do more harm than good [BBC News].

During a workout, the muscles metabolize glucose to create energy, but in the process some free radicals are released. The body has a natural defense mechanism to combat these free radicals, but many researchers had theorized that the body can’t catch all of the harmful compounds, which makes antioxidant supplements sound like a logical solution.

In the new study, published in the Proceedings of the National Academy of Sciences, the researchers tested this proposition by having young men exercise, giving half of them moderate doses of vitamins C and E and measuring sensitivity to insulin as well as indicators of the body’s natural defenses to oxidative damage.The [researchers] found that in the group taking the vitamins there was no improvement in insulin sensitivity and almost no activation of the body’s natural defense mechanism against oxidative damage [The New York Times]. The loss of insulin sensitivity is thought to be a prime cause of adult-onset diabetes.

The researchers suggest that the small amount of free radicals produced by exercise may be necessary to trigger both insulin sensitivity and the body’s natural defense mechanisms. Since the volunteers who were taking vitamins swept free radicals from their systems, those responses lay dormant. But researchers say the surprising findings don’t mean that people should avoid healthy vegetables that contain antioxidants, just that they may want to skip nutritional supplements with artificially high levels of antioxidants. Nutrition expert Elisabeth Weichselbaum comments: “If you stick to a healthy and varied diet, you generally get enough of the nutrients you need and you don’t run the risk of consuming large amounts that may be harmful for you” [BBC News].

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Image: flickr / Martineric

CATEGORIZED UNDER: Health & Medicine
  • Jumblepudding

    I always thought of free radicals as the “guns” of the body’s defense system. If they’re forced to fire too often there are going to be a lot of bullet holes and collateral damage, but total disarmament is not the answer either. That said, it’s hard to believe that just twice or three times the guideline amount of a vitamin, as you could get from a few cups of spinach, could be so bad for you. When you get into the tens or the hundreds of times the RDA, as some of these supplements do, it seems like that would be the territory of abnormal body function.

  • Nick

    The last paragraph there is the important one.

    Also, I’d like to point out that vitamin supplements, while not very well absorbed by our bodies, have sometimes hundreds or thousands of the percent RDA – AND even junk food has vitamins and other things spun into them. I’m sure, if you walk into a convenience store, you can walk out with food containing several hundred times the amount needed of a couple vitamins (especially C – C is in EVERYTHING made in a factory, except maybe twinkies).

    What this story doesn’t say, and I don’t have a subscription to the National Academy of Sciences to find out, is whether or not these young men had a controlled diet and exercise regimen leading into this study, or if they had been eating junk food and playing Nintendo 24/7 until the day before. That may play a factor in their bodies reactions – say for instance they chugged a gallon of Sunny D a day up until the study – all that sugar would make their insulin reaction very sluggish (my mom was a sugar fiend until the day they pronounced Type2 diabetes – and had to give her enough insulin to put a healthy guy like me in the I.C.U. to get her close to normal blood sugar… she used to be a big fan of the Sunny D) and all that added, soluble vitamin C that they stock Sunny D with to make it a “healthy alternative to that purple stuff” (which probably has just as many added vitamins) could leave the body naturally unreactive to doses of Vit C – the way methamphetamine use makes the body stop naturally producing dopamine because the meth triggers the receptors, fooling the brain into believing it’s producing too much dopamine and thusly ramping down production.

    Of course, these are trained scientists were talking about here, so hopefully they out-thought wankers on the internet (me) and have already controlled for these types of things.

    And except for resveratrol and vitamin B12 (as a vegetarian, not many if any natural sources of this), I don’t supplement any vitamins, I just eat a diet high in nuts and berries (and other good stuff, and of course a bunch of not so good stuff. My tongue isn’t dead I can just usually beat it with good sense.) I do supplement Omega 3 fish oils, sure I may be a bad vegetarian for doing so but compared to the smoking ruin my skin used to be before the Omega-3s, I’ll live with being a ‘bad’ vegetarian.

  • Jef

    Nick, there’s plenty of B12 in dairy and egg products. It’s really only vegans who need to take supplements for that. And you can get your omegas from flax oil, either sold as oil or you can get flax seeds and put them in your tea to soften the husks so you can digest them, or soak or grind them and put them in a smoothie or cook them into some other kind of dish. they’re really tasty and fantastic. You can also get omegas from purslane.

  • Eliza Strickland

    Nick — good question about the state of the test subjects. I checked the paper. All the test subjects were healthy young men with comparable amounts of body fat. Of the group that received the supplements, half had previously been exercising and half had not been. They all had the same lack of reaction in the experiment, with no increase in insulin sensitivity and no mustering of the body’s defenses.

    The group that didn’t receive the vitamins also had half couch potatoes and half gym rats, but all the men in this group showed strong, beneficial responses.

    And this is a good moment to say thanks, in general, for being such an intelligent commenter! I always like reading your thoughts.

  • Christina Viering

    I will keep taking my vitamins.

  • Stan

    Sounds like another flawed study done by people who either didn’t know what they were doing or intentionally designed a study to fail. They probably used cheap synthetic vitamins, and no mention of the dosages. Then they basically conclude that antioxidants may harm you, but don’t stop eating them because they’re good for you!
    They also didn’t factor in that these antioxidants are meant to work as a team with other antioxidants like lipoic acid and coenzyme-Q and the mineral selenium. You can’t test antioxidants in isolation and expect valid results.

  • chris

    I find these situations some what comical.

    Every couple of years there is a study that promotes the health benefit of some product.

    A couple of years later there is another study that shows that product is not so beneficial.

    Atleast that is how it seems in retrospect.

    Personally I do occasionaly take a multivitamin, but I’m not particularly good at keeping a regime for it.

  • Stan

    I’ve been taking supplements for 30-plus years, and lots of them… they work.

  • YouRang

    Yes they did seem to factor in lipoic acid in particular. Lipoic acid is produced by the body and is the main one of those natural body defenses.
    The main thing I found wrong with the study is: They found no improvement in insulin sensitivity; BUT they found no improvement in insulin sensitivity ACUTELY. For all they know, a little improvement now (in the non-vitamin takers) will translate into lowered improvement in insulin sensitivity later. And indeed it isn’t improved insulin sensitivity that we all need; it is maintained insulin sensitivity.
    Having said that, I stopped taking Vitamin E in doses about 200 mg/day years ago because it made me feel crappier than usual. By the same token, I don’t stop taking supplements because i also feel crappier than usual when I do.
    So bottom lines: No improvement in body’s natural defenses–SO WHAT? there’s already enough with the supplemented C and E. No improvement in insulin sensitivity. WRONG; NO improvement in ACUTE insulin sensitivity.

  • YouRang

    Amplifying. The shape of the curves is also significant. I would guess that the reality is akin to: 68% do about the same with or without,, 16% due better with supplements and 16% do a lot better without. Let’s round both 16% off to 1/4. Now we really need to ask ourselves what is the response to any one of many more stressors–say 10. Then if there is no cross-correlation, although 1/4^10( or 1 person in about a million) will always do a lot better without supplementation, 999,999 out 10^6 will do better or no worse with supplementation. It’s not the doing not as well in the iron man triathlon that will kill you; it’s the doing not as well in one of the other 9 stressors that will kill you. (at least for that ~999,800). (not sure about the exact number that would do worse (rather than the same) to at least one of the stressors–but since I rounded 1/6 to 1/4 and who knows how many stressors and since I don’t really have the data, I’m not going to worry about exactly how many would do worse ON AT LEAST 1 OF THE OTHER STRESSORS. But the badly formed test wouldn’t answer any of these questions anyway.) Even if there is only one stressor, if the shape of the curve is such that a few do a lot better without, then the average will also be skewed.

  • Dr. Charles Martin

    Interesting article. No doubt this study’s finding will be subject to additional research. It’s important to recognize that there are additional uses for antioxidants, such as the gels many dentists use to assist healing following certain procedures for gum disease. That’s particularly important to people who have diabetes because of the interactions between elevated blood sugar and gum disease. We write extensively about related issues at, especially the links between blood sugar levels and gum disease that can interfere with diabetes control and significantly increase risk of serious health events.

    – Charles Martin, DDS
    Founder, Dentistry For Diabetics

  • bandsxbands

    My friend and I were recently talking about technology, and how integrated it has become to our daily lives. Reading this post makes me think back to that discussion we had, and just how inseparable from electronics we have all become.

    I don’t mean this in a bad way, of course! Societal concerns aside… I just hope that as memory becomes less expensive, the possibility of downloading our memories onto a digital medium becomes a true reality. It’s a fantasy that I dream about all the time.

    (Posted on Nintendo DS running R4i SDHC DS NePof)

  • nightstand ikea

    Excellent article! How long have you been working your website?

  • Bill Sardi

    This is a twisted interpretation. Who cares about more insulin in physically fit athletes? And as for natural antioxidant defenses, those endogenous antioxidant enzymes like glutathione, superoxide dismutase and catalase, no, they didn’t need to be switched on because the supplemental antioxidants were doing their job. Endurance athletes smash their red blood cells and sometimes become anemic. But vitamin E helps to prevent this. The best diet could not possibly meet all the nutritional demands of athletes for optimal performance.

  • cash renegade

    Looks like I should reconsider taking all those supplements I bought. This is definitely something new to me, had not heard about this before.

  • nutritionist brisbane

    This is based on a very small sample and short trial period. As far as we can tell from the abstract, what the subjects ate during the trial period were also not known. In contrast there is a great body of research on the positive benefits of antioxidant supplementation.


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