Athletes, Why Are You Still Taking Dietary Supplements?

Health and medicine explained.
July 26 2012 6:15 AM

Athletes, Stop Taking Supplements

They’re expensive, they don’t improve performance, and they might make you test positive for dope.

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These are big promises, especially from a product whose declared ingredients consist of nothing more than some amino acids and vitamins. Like most supplements purporting to enhance athletic performance, AdvoCare’s products are not backed by peer-reviewed clinical trials, just testimonials, the endorsements of professional athletes, and some scientific advisory board members with MDs or Ph.D.s behind their names. AdvoCare says that its products are subject to testing and quality assurance standards, and that in the company’s history, there has been only one claim (from Hardy) that its products were contaminated.

When studies do appear to support supplement companies’ claims, they are usually small and at best can offer only hints of efficacy, not definitive proof. As I learned first-hand during my earnest attempt to study the effects of beer on running, even seemingly robust study designs can lead you to a dodgy conclusion. My study could have easily been interpreted to show that beer made women better runners, but as a participant of the study, I discovered problems in the standard protocols that might not have been apparent otherwise. A series of reports published July 19 in BMJ found “a striking lack of evidence to support claims about improved performance and recovery” made by products aimed at athletes like sports drinks and supplements and concluded that it is “virtually impossible for the public to make informed choices about the benefits and harms of advertised sports products.”

Despite the scarcity of evidence, athletes continue to take supplements at high rates. A 2009 study estimated that 85 percent of elite track and field athletes took supplements, and 87 percent of Canadian athletes who participated in a survey published this year reported taking dietary supplements in the previous six months.

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According to FDA rules, supplements are supposed to contain substances that could be obtained through food. That means vitamins, minerals, and nutrients like carbohydrates, amino acids, or protein. But there’s no reason to think athletes benefit from supplementing their diets with these things. Elite athletes spend hours each day training and must consume thousands of calories. It’s hard to become nutrient-deficient when you’re eating that much. The American College of Sports Medicine’s position statement says, “vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods.”

The one exception is iron, which often becomes depleted in menstruating women, especially if they don’t eat much meat. (Low iron stores can lead to fatigue and poor performance.) But you rarely see sport supplements touting iron. Instead, advertisements target athletes with dubious claims that supplements can boost red blood cells or build muscle “naturally.” And these pitches are often shrouded in pseudo-scientific language. When a supplement is promising results that you wouldn’t expect from simple good nutrition, chances are the claim is bogus or the supplement contains an illicit, undeclared drug.

The difference between winning and losing is often measured in fractions of a second, and athletes trying to bridge that gap are easy targets for quackery. After Hardy’s positive test, you’d expect her teammates on the U.S. swim team to eschew supplements, but Hardy estimates that, despite her warnings, about 90 percent of the swimmers still take them.

Coaches and trainers, too, are often fooled. Most have little scientific training, and the supplement industry bombards them with literature about nutrition. And there’s plenty of incentive to believe the hype. Endorsement deals from supplement companies provide a major source of income for many teams, coaches, and athletes, and trainers or coaches sometimes get paid to peddle supplements to their athletes.

Under the best-case scenario, a supplement provides an expensive source of a nutrient that the athlete could be getting from food. Worst-case scenario, it's providing dangerous levels of heavy metals, pesticide residues, undeclared drugs, or illicit performance-enhancers that may show up on a drug test. USADA provides detailed advice for athletes contemplating the use of supplements, including a list of red flags that should make them think twice about using a product, such as promises that they'll enhance muscle-building or energy or claims about "proprietary blends" that are "clinically proven."

Given the slew of high-profile doping cases traced back to supplements, and USADA’s concerted efforts to educate athletes, it’s hard not to suspect that some of these runners, swimmers, and cyclists know exactly what they’re doing. I have no reason to think that Hardy had any intention of doping, but cases like hers may give cover to genuine cheaters. After all, the designer steroid that took down Marion Jones and Barry Bonds was created and distributed through a supplement company—the Bay Area Laboratory Co-operative (BALCO) that gave the scandal its name.

If I were a doper, I'd be sure to have a medicine cabinet full of supplements—ones that claim to produce the same results as my drugs. Then, if I ever tested positive for doping, I'd have a plausible excuse. 

Christie Aschwanden is an award-winning writer and contributing editor for Runner's World. She blogs about science at Last Word on Nothing.