Just in time for the Olympics, the British Medical Journal has published a fascinating, though alarming investigation into the science (or lack thereof) around sports drinks (h/t to Medical Skeptic for the link). It turns out that many hydration mantras we take for granted—drink before you feel thirsty, stop to drink every 15-20 minutes, use sports drinks to replace electrolytes lost in sweat—may actually be myths propagated by the beverage industry and the scientists it funded. In BMJ’s words:
…companies have sponsored scientists, who have gone on to develop a whole area of science dedicated to hydration. These same scientists advise influential sports medicine organisations, which have developed guidelines that have filtered down to everyday health advice. These guidelines have influenced the European Food Safety Authority, the EU agency that provides independent advice on the evidence underpinning health claims relating to food and drink. And they have spread fear about the dangers of dehydration.
This process is less simple than it might seem; sports drink makers haven’t mouthed off directly to the European Food Safety Authority (their version of the FDA). Rather, over decades, they sponsored scientists who in turn spawned an entire scientific field around hydration. The industry “formed partnerships” with seemingly impartial organizations and regulatory bodies, like the US National Athletic Trainers’ Association and even the International Olympic Committee, donated large sums to medical societies like the American College of Sports Medicine, and established its own decidedly partial research engines, like the Gatorade Sports Science Institute. Eventually, scientists with relationships to the sports drink industry formed the leadership of many leading journals in sports medicine.
For one sports drink alone, Lucozade, the manufacturer provided 106 studies substantiating its effectiveness to the BMJ’s investigators. Sounds solid right? Unfortunately it wasn’t; the investigators found that they were very poorly designed, with low sample sizes (median sample size=9), no blinding, and intermediate outcomes galore, among other things. But perhaps the worst of it is what we can’t see–studies showing that sports drinks are ineffective are conspicuously absent from the literature. In the words of a sports scientist quoted throughout BMJ’s article, “a commercial company would never do research that it was not certain of the answer before it did the study.” And if an unfavorable answer did come out, they definitely wouldn’t try to publish it. Perhaps most insidious is the possibility that industry relationships are preventing journals from giving negative research a fair shot at publication:
Several people have told the BMJ how difficult it is to publish studies that question the role of hydration. Paul Laursen is one of them. “[A negative study] gets rejected by reviewers and the editors for really spurious reasons—particularly when you consider what does get published. It’s a frustrating experience and it makes you wonder if it’s a case of money winning out.”
If all this is starting to sound familiar, it should. Scientific journals consistently prefer papers that propose new ideas over those that refute old ones–a problem known as “publication bias.” And though we have laws to prevent authors from burying clinical studies with undesirable results, those laws haven’t worked. To me, reading about the sports-drink “research” smacked of even more egregious stories, like the tobacco industry’s coverup of the research linking smoking to cancer. Now, I think we can all agree that promoting sports drinks through tenuous science isn’t nearly as unethical as hiding sound science that links cigarettes to cancer. Even if the industry is completely wrong about sports drinks, it’s not like they were selling us poison, right?
Strictly speaking, no. Not poison. There is certainly a place for sports drinks: when I hiked in and out of the Grand Canyon in June, a long trek through bone-dry heat approaching 120 degrees, I learned that the leading causes of death on the trails were dehydration and its evil twin hyponatremia (excessively low sodium levels, caused by drinking water without replenishing salt lost to sweat). We might not have made it out alive without gallons of water and electrolyte supplements. Even then, however, our electrolyte tablets had far less sugar than a Gatorade, and could probably have been replaced by peanuts or pretzels—anything that gets the salt back in you.
For most other situations, though, the sports drink industry has plied its wares in a way that could hurt our long-term health, even if not as visibly as a cigarette blackens a lung. An ordinary workout, basketball game, or day at the office does not have nearly the same effect on your physiology as a marathon or a ten-hour hike in the desert. Consider the numbers: a 24-oz Gatorade has 160 calories, all from sugar. On a three-mile run, a 150-lb individual burns about 340 calories. If you’re running to lose weight but pound a Gatorade as soon as you get back, you’ve erased almost 47% of your hard-earned progress—let’s not even get into reward eating. But you still get points for running; the BMJ points out that one in four people have sports drinks at their desks, presumably without any workout at all. Problems arise when sports drinks with nearly no positive nutritional value are labeled a “healthy choice”—especially when those doing the labeling are the scientists and physicians we trust for objective, credible advice.
I’m happy to concede that sports drinks have their place. But is that “place” really youth soccer games, worn-in recliners, or the hands of the millions struggling to lose weight for their health’s sake? We’ve come a long way by starting a national conversation on the dangers of added sugar (see Mayor Bloomberg’s soda ban for one), but if that conversation starts and stops with soft drinks, we’re leaving a big, hairy, sweaty part of the beast untouched.
Karan works in strategic research on health care and will begin medical school this fall.
Follow him on Twitter @KRChhabra.