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Posts Tagged ‘supplements’

Steven Blair on “magic bullets” vs. lifestyle change

June 30th, 2011

The U.S. government plans to spend $1 billion on a new NIH centre on “Advancing Translation Sciences.” Great news, right? Not according to James Hebert and Steven Blair of USC, who have a new commentary just posted online at the British Journal of Sports Medicine:

This plan typifies the search for a ‘magic bullet’, in pill form, that will cure all diseases and health problems…

[L]arge drug companies have spent ~US$400 billion on drug research over the past 15 years. We should examine the effectiveness of this huge expenditure in terms of public health benefits… What happens in a society in which people are told that pills are available to put them to sleep, wake them up, stimulate them, calm them down and control appetite and body weight? We argue that the answer is in the growing number of people with mental disorders including depression and anxiety, sleep disorders, deteriorating nutritional status and increasing rates of obesity unprecedented in human history. The pills that have been developed, advertised on television and demanded by a desperate populace have been spectacular in their inability to address the major and growing public health problems of the USA.

Instead, Hebert and Blair want to see more emphasis on lifestyle change. They cite some interesting data from studies comparing lifestyle and pharmaceutical interventions. For example, a study found that just three or four sessions with a dietician produced the same reduction in total and LDL cholesterol as taking statins. And two randomized trials found that “lifestyle interventions” were twice as effective as drugs in preventing high-risk individuals from developing diabetes. The authors are “puzzled and concerned” that results like these haven’t received more publicity and follow-up.

So what’s the solution? They suggest an NIH “National Institute for Improving Healthy Lifestyles” instead of the translational medicine institute. Would this make a difference? It seems to me that if we knew how to get people to change their lifestyles, we’d already be doing it. But perhaps they’re right: with enough resources — and $1 billion would be a pretty good start! — maybe lifestyle change wouldn’t look quite so daunting.

We understand that while changes in diet and physical activity are conceptually easy, they are diabolically difficult to do in practice. The promise of even easier solutions to cure the consequences of years of sloth needs to be debunked.

That, I think, is the key point. We need to stop promising that getting healthy will be easy, and emphasize instead that it’s worthwhile. To borrow a thought from physics, it’s like that Einstein quote: “Everything should be made as simple as possible, but not simpler.”

Vitamin supplements and risk homeostasis

May 3rd, 2011

Just when I thought I’d extricated myself from the great “bike helmets and risk homeostasis” debate, along comes a study suggesting that taking multivitamin pills causes people to behave in less healthy ways for the rest of the day. Even worse, the title of the paper in Psychological Science (“Ironic Effects of Dietary Supplementation: Illusory Invulnerability Created by Taking Dietary Supplements Licenses Health-risk Behaviors”) is likely to start an even fiercer debate about the correct use of the word “irony.” (Maybe it’s just a pun, since some multivitamins contain iron.)

But seriously, folks… The researchers gave a bunch of volunteers a harmless placebo pill; half of them were told it was a placebo, while the other half were told it was a multivitamin. Then they did some experiments and found that those who thought they’d taken a multivitamin “expressed less desire to engage in exercise and more desire to engage in hedonic activities, preferred a buffet over an organic meal, and walked less to benefit their health than the control group.”

It would be silly to take this study as evidence that multivitamins are “bad.” Still, I can’t help feeling that it does point toward a trade-off that people may unconsciously make when they look for “exercise pills” and other shortcuts. Most of the athletes I know take multivitamins as a way of “covering their bases” in case their diet falls short — as, in the real world, it occasionally will. But are there times when it only falls short because they feel that it’s okay to cut corners because they’ve got the pills as back-up? That’s what this study suggests. Maybe it’s better to take away the safety net, so you have more motivation to stay on top of your diet.

Does vitamin C block gains from training?

April 24th, 2011

The traditional theory goes like this: strenuous exercise produces “reactive oxygen species” (ROS), which cause damage to cells and DNA in the body. Taking antioxidant supplements like vitamins C and E helps to neutralize the ROS, allowing the body to recover more quickly from workouts.

The new theory, in contrast, goes like this: strenuous exercise produces ROS, which signal to the body that it needs to adapt to this new training stress by becoming stronger and more efficient. Taking antioxidant supplements neutralizes the ROS, which means the body doesn’t receive the same signals telling it to adapt, so you make smaller gains in strength and endurance from your training.

So which is true? Back in 2009, a German study found that vitamins C and E did indeed block gains in insulin sensitivity — a key adaptation to exercise — in a group of sedentary volunteers. But in January 2010, a study of cyclists found no difference in fitness parameters like maximal oxygen consumption, power output, lactate threshold and so on between a placebo group and a vitamins C/E group. But then last December, a study with rats found that vitamin E did block gains in mitochondria, a key adaptation to endurance training.

Which brings us to the most recent study, published in March in the International Journal of Sports Physiology and Performance. A total of 17 recreational runners did a four-week training program consisting of four interval workouts a week (5x3min hard with 3min jog recovery — a bit of an odd program, but it succeed in significantly boosting VO2max, running economy, 10K time trial performance, etc.). Half the subjects took 1 gram of vitamin C every morning, while the other half took a placebo; the trial was double-blinded, so no one knew who was in which group. The results: no significant differences between the groups.

So where does this leave us? I’m not really sure. The paper discusses a couple of possible explanations. One is that antioxidants do block some training gains but that this study was too small to detect them. With nine subjects in one group and eight in the other, that’s certainly possible. For example, the subjects ran two  “YoYo Intermittent Recovery Tests” with slightly different parameters. In the first one, the vitamin C group improved 22% while the placebo group improved only 16%; in the second one, it was the other way around, with the placebo group improving 10% and the vitamin C group improving only 5%. This doesn’t give me a whole lot of confidence in the test-retest variability, or the ability to detect subtle differences in adaptation.

Another possibility relates to the initial fitness of the subjects. The 2009 German study used sedentary, unfit subjects, who thus would be expected to produce very high levels of ROS in response to the unfamiliar stress of exercise. In these subjects, one might expect antioxidant supplements to make a bigger difference to training adaptations. The new study, on the other hand, used subjects with higher initial aerobic fitness (“recreationally active,” not trained athletes). As the saying goes, “exercise is the most powerful antioxidant we have.” So it’s possible that fit subjects already have reasonably effective natural antioxidant defenses in place, so taking additional antioxidant supplements doesn’t make as much (or any) difference.

All of this leaves us with no firm answer — as usual, more studies are needed. My guess (thinking back to my last post about the pros and cons of training on empty) is that we’ll eventually conclude that the answer is “it depends.” Perhaps antioxidant supplements will be helpful during extremely heavy training blocks, but should be avoided as you approach competition. Or perhaps it’s the other way around: let the ROS run wild during heavy training blocks, but take antioxidants to ensure full repair as competition approaches. The latter approach fits with a Portugese study that found that antioxidants may delay muscle repair after heavy workouts, but could allow muscles to actually work harder in the heat of competition. It’s too soon to know for sure.

The beet goes on: nitrates improve cycling time trial performance

April 13th, 2011

Wow. This study is really impressive. Drinking 500 mL of beet juice 2.5 hours before a cycling time trial improves 4 km TT time by 2.8% and 10 mile TT time by 2.7%. On the one hand, this shouldn’t be surprising, because there have been a bunch of recent studies showing beet juice boosting time-to-exhaustion and reducing oxygen cost… But still, those types of studies often don’t end up translating into real differences in the parameter that matters: actual performance. So, as I said: Wow.

The study, published online last week in Medicine & Science in Sports & Exercise, is legit. It’s from Andrew Jones’s group in Exeter. It’s a properly designed placebo-controlled crossover study. The placebo was beet juice with the nitrates (the active ingredient) filtered out with an ion resin, thus indistinguishable from the active beet juice. The subjects (nine competitive cyclists) visited the lab at least five times before the actual experiment even started, to practice taking the time trials until they achieved repeatability of less than 1%.

To reiterate what’s most striking:

  • Performance benefits of 2.8% (6.26 vs 6.45 min) over 4 km and 2.7% (26.9 vs 27.7 min) over 10 miles.
  • This improvement was achieved with just one dose of 500 mL of beet juice, taken 2.5 hours before the event. (Note that this dose is equivalent to 1.6 kg of spinach or 3.1 kg of lettuce!)

They also took other measurements: the amount of oxygen used was the same with and without nitrates, but the power generated was higher with nitrates. Also, plasma level of nitrites was higher after the beet juice, consistent with previous studies suggesting that the beet juice works because nitrates are converted to nitrites then to nitric oxide, which lowers the oxygen cost of muscle contractions.

On another note (further to this previous post):

The subjects also abstained from using antibacterial mouthwash and chewing gum during the supplementation periods since these are known to eradicate the oral bacteria which are necessary for the conversion of nitrate to nitrite.

So what more is there to say, other than “Buy stocks in beet juice companies pronto”? Well, one caveat is that it hasn’t yet been shown that these results can be duplicated in elite athletes. It’s notoriously easier to produce big improvements in less-trained athletes, and these subjects were recreationally competitive. So further studies will be required in elites. But it’s time to acknowledge once again that my initial predictions when I first heard about this research in August 2009 were wrong, wrong, wrong!

How nitrate (and beets) work, and why mouthwash is bad

February 8th, 2011

The performance-boosting effect of beet juice, attributed to the nitrate it contains, has been one of the biggest sports science stories of the past year. A few days ago, Swedish researchers published a new study in the journal Cell Metabolism (press releases here and here) that answers some questions about how nitrate works — and raises some questions about whether mouthwash might actually hurt your performance. Interestingly, this Swedish group has been publishing results on the performance-boosting effects of nitrate since 2007. It’s only when Andrew Jones’s group at the University of Exeter started publishing results in 2009 using beets instead of isolated nitrate that everyone started paying attention.

The study: a randomized, double-blind crossover trial with 14 subjects given either 0.1 mmol/kg of sodium nitrate or a placebo each day for three days. Since their previous studies have shown that this protocol allows subjects to use less oxygen while cycling at a given intensity, this time they looked for the root cause. They isolated mitochondria (the cellular “power plants” that generate ATP to fuel muscle contractions) in the subjects. Sure enough, the mitochondria from the nitrate group used less oxygen to generate a given amount of ATP. Further (rather complicated) experiments suggested that this is because nitrate leads to lower levels of a protein that causes efficiency-sapping proton leakage across the mitochondrial membrane.

So what does it mean? Well, the researchers suggest that it might be nitrate (which, as they note, “has previously been considered merely as an inert end product of NO metabolism or as a potentially toxic constituent in our diet” — think hot dogs) that is responsible for the well-known but poorly understood health benefits of a diet high in vegetables (particularly leafy green ones). And of course, it’s more evidence that nitrate might be the real deal as an ergogenic aid for endurance athletes.

But what really caught my attention was the following offhand remark in one of the press releases:

As an interesting aside, Weitzberg says that the benefits of dietary nitrates suggest that powerful mouthwashes may have a downside. “We need oral bacteria for the first step in nitrate reduction,” he says. “You could block the effects of inorganic nitrate if you use a strong mouthwash or spit [instead of swallowing your saliva]. In our view, strong mouthwashes are not good if you want this system to work.”

Huh? Here’s a brief explanation from the paper itself about how nitrate is used by the body:

Circulating nitrate, normally derived both from endogenous NO [nitric oxide] production and from dietary intake, is actively taken up by the salivary glands, excreted in saliva, and reduced to nitrite by commensal bacteria in the oral cavity.

The statement about mouthwash having a negative effect is just speculation at this point, not backed up by any studies. But it’s interesting…

UPDATE Feb. 9: Thanks to Colby for pointing out that the same Swedish group has actually already done a study looking at the effects of mouthwash, published back in 2008. The gist is as follows: the nitrate we take in through our diet is converted first to nitrite then to nitric oxide, which is what has a positive effect on blood pressure, performance and other parameters. But our cells are unable to convert nitrate to nitrite — to make that conversion, we rely almost exclusively on friendly bacteria in our saliva. To test that hypothesis, the researchers fed nitrate (the equivalent of about 300 g of spinach or beets) to volunteers 15 minutes after they gargled with an antibacterial mouthwash (Corsodyl). Here’s what they saw:

Even though nitrate levels in saliva were similar, the bacteria needed to convert nitrate to nitrite was gone in the mouthwash experiments, so nitrite levels in saliva remained flat. As a result, nitrite levels circulating in the blood (which is what’s shown above) increased far less in the mouthwash than the non-mouthwash case.

Unfortunately, this still doesn’t tell us much about timing and chronic effects. If you mouthwash before bed, will your nitrate-to-nitrite conversion still be impaired at dinner the next day? I really don’t know. I’m certainly going to keep mouthwashing — but it might make me think twice about the gratuitous middle-of-the-day extra gargle!

Beet juice: it’s the nitrates, stupid

January 4th, 2011

More research from Andrew Jones’s group at the University of Exeter on the endurance-boosting effects of beet juice, which they previously reported can extend time-to-exhaustion by about 15% (equivalent to about a 1% improvement in a race over a specific distance), in a forthcoming paper in the Journal of Applied Physiology (press release here).

The most interesting new twist: they’ve developed a way of filtering the nitrates out of beet juice using an “ion-exchange resin,” allowing them to create a placebo form of beet juice that is identical to the real thing in every way except for the absence of nitrates. They’ve hypothesized that it’s the nitrate in beet juice that reduces the “oxygen cost” of running and other endurance exercise — i.e. you burn less energy to produce the muscular force needed to propel yourself forward, allowing you to last longer. But beet juice has a whole bunch of potentially beneficial ingredients, including big names like quercetin and resveratrol, so they needed some way to check which ingredient was actually making the difference. The new double-blinded study does that nicely: the nitrate-free beet juice had no effect on subjects, while the regular beet juice lowered blood pressure and improved performance in various endurance running tests.

One other new result is that they tested low-intensity exercise as well as high-intensity. Sure enough, they found that the oxygen cost of walking was significantly decreased after just four days of drinking 500 ml of beet juice per day.

For senescent populations or individuals with pulmonary, cardiovascular or metabolic disorders, [they write,] a reduction in the O2 cost of daily activities might significantly improve functional capacity.

Maybe, maybe not — I’m not convinced seniors will really care about shaving 1% from their evening walk time. But for competitive athletes, the body of evidence for beet juice is getting solid enough to make me reconsider my initial skepticism. I’d like to see similar results from other labs, though.

Placebos without deception still work

January 3rd, 2011

One of my greatest regrets about writing this blog is that the more I dig into the evidence behind most of the supposed “performance-boosting” supplements out there, the less I believe most of them have any legitimate effect. If I never looked at the actual research, I could be popping all sorts of pills in blissful ignorance — and because I’d believe in them, they’d give me a nice robust placebo effect. In fact, I’ve toyed (mostly in jest) with the idea of suggesting that elite athletes should avoid finding out too much about the science of ergogenics, so that they can maintain the fantasy that these things work and thus get an edge from them.

But a recent study from Harvard suggests that one of my key assumptions may be false. The study (which is freely available here and described by a press release here) set out to determine whether you have to believe in a placebo in order for it to work. To that end, they recruited 80 patients with irritable bowel syndrome (IBS). Half of them received no treatment, while the other half received placebo pills to take twice daily — but they knew that the pills were nothing but sugar:

“Not only did we make it absolutely clear that these pills had no active ingredient and were made from inert substances, but we actually had ‘placebo’ printed on the bottle,” says Kaptchuk. “We told the patients that they didn’t have to even believe in the placebo effect. Just take the pills.”

To everyone’s surprise, nearly twice as many placebo patients reported relief from their symptoms (59% vs. 35%), and “patients taking the placebo doubled their rates of improvement to a degree roughly equivalent to the effects of the most powerful IBS medications.”

So what on earth is going on here? The researchers speculate that “there may be significant benefit to the very performance of medical ritual.” This isn’t a new idea — I read a very interesting book on the placebo effect a few years ago that argued, in effect, that the doctor-patient relationship is the most powerful placebo mechanism available to us. Of course, “feeling better” is not the same kind of outcome as “running faster” or “growing bigger muscles.” I’d love to see a study that investigated whether undisguised sugar pills could enhance athletic performance. What would WADA do if the results came back positive? 🙂

Antioxidants block gains from endurance training

December 9th, 2010

Another study on antioxidant supplements, this one from researchers at the University of Queensland in Australia, published online in Medicine & Science in Sports & Exercise.

The study was with rats: 14 weeks of supplementation with vitamin E and another antioxidant called alpha-lipoic acid, training four times a week. The antioxidants suppressed the growth of new mitochondria (the “power plants” of your cells), which is one of the primary adaptations to endurance training. One of the new wrinkles to this study compared to previous ones is that growth of mitochondria was suppressed even in rats that weren’t training, if they took the supplements.

I’ve written several times before about this area of research. The idea is that “reactive oxygen species” (ROS) are generally bad, and antioxidants fight them. But when you exercise, the ROS you produce are the “signals” that tell your body to adapt, so if you take antioxidants, your body doesn’t realize it’s supposed to adapt and get stronger (or grow more mitochondria or whatever).

The conclusions are far from clear — for instance, this study didn’t find any reduction in the benefits of endurance training from antioxidants. But given how little evidence there is that these types of supplements actually help, the potential costs certainly seem to outweigh the benefits.

Beta-alanine: a boost for anaerobic power… and finishing sprint?

November 26th, 2010

In general, I’m not a big fan of performance-boosting supplements, in part because of some vague notions of “the spirit of sport” and in part because the vast majority of them are expensive placebos. But one of the sessions at the sports nutrition conference in Canberra earlier this week made a strong case that beta-alanine now has enough evidence to join the very, very short list of supplements with solid performance-enhancing science behind them (e.g. caffeine, creatine). The first important study of beta-alanine was only in 2006, but there have been 27 more studies since them, according to Trent Stellingwerff, a researcher at the Nestle Research Centre in Switzerland who also works with Canadian Olympic teams.

(Sorry for the delay in reporting on the sports nutrition conference — really busy week! There’s lots more to come, which I’ll post over the next few weeks.)

Basically, beta-alanine works just like baking soda to buffer pH, but does it from inside the muscle rather than outside (and, happily, doesn’t cause diarrhea). The actual buffering agent is something called carnosine, which is present in meat. When you eat meat, the carnosine is split into its two constituent amino acids (beta-alanine and histidine), which are absorbed into your muscles and recombine to form carnosine again. The rate-limiting step is the absorption of beta-alanine into your muscles, so if you take some extra beta-alanine you end up with more carnosine.

So when does this work? The sweet spot is thought to be exercise lasting between 60 seconds and 10 minutes. Studies dating way back to the 80s showed that sprinters have twice as much carnosine in their muscles as marathoners do. More recently, a Belgian study measured baseline carnosine levels in a group of rowers (i.e. without supplementation) and found that higher carnosine levels correlated to higher performance. Supplementing with beta-alanine then led to a 4.3-second improvement over ~6 minutes for the rowers.

The dosing details: unlike baking soda, it’s not a one-shot deal. Trent suggests that taking 3-6 g/day for four to eight weeks will increase muscle carnosine content by 40-50%. It then stays high for quite a while, so you can expect to continue seeing a performance boost up to a month after stopping supplementation.

For endurance athletes, there are a couple of potentially interesting wrinkles. A 2009 study in the Journal of Applied Physiology (Van Thienen et al.) found that cyclists on beta-alanine performed better in a 30-second all-out sprint at the end of a 110-minute time trial. So the buffering might help with the anaerobic demands of a finishing sprint even during a very long race, though this is just one study so far.

The other thing to consider is whether beta-alanine could help endurance athletes sustain higher levels of intense training — after all, interval sessions often include intense running within that 60s-10min sweet spot. Stellingwerff, who coaches a bunch of athletes including his wife, a 4:05 1,500m runner, gave one piece of practical advice. He said for a workout like 10x400m, athletes on beta-alanine tend to feel really good in intervals 1, 2, 3 and 4 — in fact, they sometimes feel too good and wreck the rest of the workout, so that intervals 7, 8, 9 and 10 get really ugly.

Anyway, food for thought. But as Trent pointed out, there’s no point even thinking about these kinds of supplements if you haven’t already taken care of the far more important basics of good diet and recovery and so on.

Vitamin C, not D, helps acute-care hospital patients

September 28th, 2010

Over the past few years, I’ve become increasingly skeptical about the benefits of taking vitamin C (and other antioxidant) supplements. On the other hand, vitamin D research has looked increasingly promising. So here’s a study from Montreal’s Jewish General Hospital that suggests I should keep my mind open:

In a double-blind clinical trial, patients admitted to the JGH were randomly assigned to receive either vitamin C or vitamin D supplements for seven to ten days. Patients administered vitamin C had a rapid and statistically and clinically significant improvement in mood state, but no significant change in mood occurred with vitamin D, the researchers discovered.

Now, this is a fairly specific population being studied, so the results aren’t generalizable. Apparently about 20% of the acute-care patients in that hospital “have vitamin C levels so low as to be compatible with scurvy,” so it’s not surprising that vitamin C helped. Ultimately, this is simply more evidence that supplements are useful for treating deficiencies; it doesn’t say anything about whether supplements provide any benefits for healthy people.