Tag: supplements

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Vitamin D study looking for participants

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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I’ve spent quite a bit of time reading the research on supplements over the past few years — and frankly, the more I read, the less inclined I am to use any. But there is one supplement I’m taking right now (having started a few months ago), and that’s vitamin D. I’ve heard enough enthusiasm from researchers I trust, and seen enough suggestive results, to decide that it’s worth a try — especially during the depths of a Canadian winter.

So why should I expect vitamin D to turn out any differently from all the other “miracle vitamins” that have preceded it and then been debunked? That’s the question that Tara Parker-Pope tackles in this entry on her Well blog. Her main point:

Although numerous studies have been promising, there are scant data from randomized clinical trials. Little is known about what the ideal level of vitamin D really is, whether raising it can improve health, and what potential side effects are caused by high doses.

And since most of the data on vitamin D comes from observational research, it may be that high doses of the nutrient don’t really make people healthier, but that healthy people simply do the sorts of things that happen to raise vitamin D.

Obviously, we need to figure these things out — which is where a new study comes in. The VITAL study is currently enrolling 20,000 older adults to take part in a five-year, placebo-controlled trial of vitamin D and omega-3 fatty acids. They’re looking for people all over the U.S. (no clinic visits are required, and all the pills will be mailed). If you’re interested, the details are here.

For now, I’ll keep taking vitamin D. But it’s worth remembering where the current research stands — and that many previous “miracle vitamins” have failed to pass the hurdle represented by the VITAL study.

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Tylenol’s pain-blocking boosts endurance performance

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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To the scientist in me, this is a really interesting study. But to the athlete and fan in me, it seems like bad news. British researchers fed highly trained cyclists acetominophen (Tylenol, as it’s known around here) before a 10-mile time trial. It was a double-blind, placebo-controlled trial. The riders who were fed Tylenol cycled about 2% faster, and had higher heart rate and lactate production (i.e. they were working harder) — but their perceived exertion was identical to the placebo group’s.

To read more about the study and its implications, read this entry in Amby Burfoot’s Peak Performance blog, which includes a Q&A with one of the researchers. The basic interpretation is simple: Tylenol blocks pain, and pain is what makes us slow down during long races. This is an important scientific result, because it sheds light on a red-hot debate about the nature and origins of fatigue. The authors of the study view their results as supporting the “central governor” theory, which argues that our brain subconsciously makes sure that we never let our body get too close to its absolute limits.

This, of course, is not the main message that many athletes will take from the study. A 2% performance boost is nothing to sneeze at for the well-trained athlete, so I expect that many athletes will start experimenting with Tylenol in training and racing. Is this dangerous? I don’t really know. (Gretchen Reynolds wrote an interesting article last summer about the risks athletes incur by overuse of NSAIDs like ibuprofen; Tylenol is a different class of drug.) But I have to admit: whenever I see a study of a potentially performance-enhancing pill, I cheer when the results come up negative, because (in my view) it keeps the sport a little simpler.

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More quercetin: a (tiny) endurance boost

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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Last fall, an excellent University of Georgia study failed to confirm the endurance-boosting effects of the supplement quercetin that earlier mouse studies had suggested. Now there’s a new study on quercetin from David Nieman’s highly respected lab at Appalachian State University, in the February issue of Medicine & Science in Sports & Exercise — and the news is mixed.

Reading the abstract, you might conclude the double-blinded crossover study was a success: they found “a small but significant improvement in 12-minute treadmill time trial performance” after two weeks of 1,000 mg of quercetin a day. Quercetin is a flavonoid that is thought to enhance the growth of new mitochondria, which is the most significant adaptation resulting from endurance training. So they also performed muscle biopsies, but these didn’t show a significant effect (though there were “insignificant increases”).

When you read the study closely, even the treadmill improvement is a disappointing result. An earlier study from the same lab had failed to find any improvement for well-trained cyclists in 5-, 10-, and 20-km time trials. So they hypothesized that the benefits of quercetin wouldn’t show up for well-trained athletes, who already have a high density of mitochondria. This study specifically enrolled sedentary young adults: the maximal exercise level permitted was 20 minutes, twice a week.

In other words, these were subjects ripe for LARGE improvements. What they found was an improvement of 2.9% in treadmill distance, while the placebo group actually got 1.1% worse. It is statistically significant (barely: P=0.038), but it’s hard to argue that it’s practically significant. For people this sedentary, an occasional walk around the block would have done more. An improvement of a percent of two is only really significant for elite athletes — precisely who this study wasn’t aimed at.

The authors acknowledge that the effect is far smaller than that seen in mouse studies, and they conclude that further research is needed with higher doses and longer study periods. This sounds like a good idea — but until those studies come in, the logical assumption is that quercetin doesn’t offer any practical benefit for people of any fitness level.

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Antioxidants and exercise update

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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The idea that popping antioxidant supplements doesn’t help — and may even counteract — some of the benefits of exercise and training is something I’ve written about several times, most recently here. So I’m duty-bound to point out the latest study, due in a future issue of Medicine & Science in Sports & Exercise (abstract available here).

The gist: 12 weeks of strenuous, supervised bicycle training, five days a week. Supplement with vitamins C and E or placebo, double-blinded. A whole bunch of physiological parameters were measured as outcomes (maximal oxygen consumption, maximal power output, workload at lactate threshold, glycogen concentration, citrate synthase, [beta]-hydroxyacyl-CoA dehydrogenase activity, if you’re interested in the details). The result:

[T]here were no differences between the two groups with regard to any of the physiological and metabolic variables measured… Our results suggest that administration of vitamins C and E to individuals with no prior vitamin deficiencies has no effect on physical adaptations to strenuous endurance training.

Of course, there are many other purported benefits to these vitamins, such as on immune function. But chalk this up as another data point in an ongoing story.

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The American Dietetic Association’s new position on nutrient supplementation

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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I’ve written a bunch about supplements recently, but bear with me for one more quick post. The American Dietetic Association just released its new position stand on “nutrient supplementation.” (The full text is available here.) A few interesting nuggets in there — for one, they note that supplement sales in the U.S. totalled an astounding $23.7 billion in 2007. About half of Americans take dietary supplements, and in particular about a third take a multivitamin/mineral (MVM). However you slice it, that’s a lot of money.

The basic gist of the position stand is as follows:

It is the position of the American Dietetic Association that the best nutrition-based strategy for promoting optimal health and reducing the risk of
chronic disease is to wisely choose a wide variety of nutrient-rich foods. Additional nutrients from supplements can help some people meet their nutrition needs as specified by science-based nutrition standards such as the Dietary Reference Intakes.

Pretty basic stuff. As you read further, it gets a little more forceful:

Although MVM supplementation can be effective in helping meet recommended levels of some nutrients, evidence has not proven them to be effective
in preventing chronic disease. A study published in 2009 from the Women’s Health Initiative found no association between MVM supplementation and cancer or cardiovascular disease risk or total mortality in postmenopausal women…

They then do a pretty good job of summing up the evidence for and against various health claims, like vitamin B-12 and cognitive function, vitamin D and bone health and so on. If you’re taking vitamins, it’s worth a look to see what they have to say about the benefits you’re looking for (though it’s a far from comprehensive list).

The bottom line for me (as I ranted in a recent comment) is that supplements offer many people a false sense of security with, in many cases, very little evidence to back them up. Eating enough fruits and vegetables is a real challenge — one that I certainly struggle with, especially at this time of year — but I’m not sure it’s helpful to convince ourselves that coming up short doesn’t matter because we’re taking some pills that will compensate.