The Controversial Science of Sports Drinks

A history of the conflated science of hydration and how consumers came to believe that "water is not enough."


[Toru Hanai/Reuters]

The British Medical Journal published a scathing investigation yesterday into the influence of the sports drink industry over academia, in the interest of marketing the science of hydration. The lengthy piece by Deborah Cohen documents how, over the past several decades, mandates regarding the necessity of hydrating during exercise entered the public consciousness to the point that they're now thought of as common sense. Here are some highlights:

  • The key players: Pepsico, which produces Gatorade, the Coca-Cola company, which owns Powerade (the official sports drink of the Olympics), and GlaxoSmithKline (GSK), which makes the British sports drink Lucozade.
  • Before the hype: The first New York marathon, in 1970, inspired a new interest in running. At the time, however, little scientific attention was played to the role of hydration in runners' performance. Throughout the 1970s, in fact, "marathon runners were discouraged from drinking fluids for fear that it would slow them down."
  • Undermining the body's signals: Cohen claims that one of the greatest accomplishments of the Gatorade Sports Science Institute, established in 1985, was to convince the public that thirst is an unreliable indicator of dehydration. There is ample evidence of ways in which the experts who propagated this information were funded or "supported" by sports drinks companies, and while this in itself isn't necessarily wrong, she argues that researchers who have conflicts of interest are not objective enough to be writing guidelines, as is the case here. There is no good evidence to support the ideas, for example, that "Without realizing, you may not be drinking enough to restore your fluid balance after working out" (Powerade), or that urine color is a reliable indicator of the body's hydration levels.
  • A better alternative to water: The journal recounts that hyponotraemia -- a drop in one's serum sodium levels -- has a bad track record of causing illness and death in marathon runners, and that we know that drinking too much water can cause hyponatremia. But it then makes the point that sports drinks do not preclude hyponatremia and that there was an article in The New England Journal of Medicine that found no correlation between hyponatremia and the type of fluid consumed.
  • Starting young: Both GSK and Gatorade have developed school outreach programs that further the case for sports drink consumption during exercise. Though the Institute of Medicine says that, in children, "Thirst and consumption of beverages at meals are adequate to maintain hydration," studies either directly funded by or involving authors with financial ties to Gatorade make a major case for the need to promote hydration, claiming, for example, that "children are particularly likely to forget to drink unless reminded to do so."
  • Distinguishing between Olympic athletes and the rest of us: The European Food Safety Authority upheld the claims that sports drinks hydrate better than water and help maintain performance during endurance exercise -- but added that this did not apply to the ordinary, light exerciser. Says Tim Noakes, Discovery health chair of exercise and sports science at Cape Town University, "They are never going to study a person who trains for two hours per week, who walks most of the marathon -- which form the majority of users of sports drinks," and the majority of people at whom sports drinks marketing is aimed.
  • Flawed research: GSK was the only company that provided the BMJ with a list of studies attesting to the beneficial effects of sports drinks, which identified a number of major flaws in their methodology: small sample sizes, poorly designed research, data dredging, and other problematic practices. Upon analysis, the journal concludes that "only three (2.7%) of the studies the team was able to assess were judged to be of high quality and at low risk of bias."  Scientists with links to the manufacturers of sports drinks have prominent editorial roles in key journals in sports medicine. Cohen suggests a link between this and that negative studies questioning the role of hydration are, according to sources, extremely difficult to get published in journals.
  • Harmful, not healthful: And, of course, there is the suggestion that sports drink consumption among children is contributing to growing obesity levels. Their association with hydration and athletics means they're not thought of as being unhealthy in the way that other sugary drinks, like soda, are (note that Mayor Bloomberg included sports drinks in his super-size ban). Several studies highlight consumer beliefs that sports drinks are healthy, even essential, showing just how far marketers have been able to push exercise science in the support of sports drinks.

Cohen concludes with an argument that dehydration has been overblown into the "dreaded disease of exercise," in yet another example of fear mongering for the sake of corporate interest.