The timing of this series, which was done in conjunction with the Centre for Evidence-Based Medicine in Oxford and the BBC’s investigative TV show Panorama, couldn’t be better, of course. We’re about to be barraged with ads for these products as the Olympics get under way in London later this week.
The papers, seven in all, are bad news for the multibillion-dollar sports-drink industry. The investigation found “a striking lack of evidence” that these products do anything to improve performance or recovery from athletic activities. The papers also offer a cautionary tale for consumers. For not only are sports drinks a waste of money, says this investigation, they can also be harmful to your health.
Little evidence for claims
In one of the papers, researchers reported that performance-enhancing claims about sports-related drinks (including protein shakes), supplements, footwear, clothing and devices (such as wristbands) are very rarely supported by any kind of scientific evidence. In fact, more than half of the 1,035 online advertisements the authors of the paper examined cited no sources — zilch — to back up their products’ performance-enhancing claims. Even when product manufacturers did provide references for their claims, 84 percent of those references were found to have a high risk of bias. Only three of the referenced studies (2.7 percent) were judged to have both a high-quality design and a low risk of bias.
“It is virtually impossible for the public to make informed choice about the benefits and harms of advertised sports products based on the available evidence,” the article’s authors concluded.
Another paper, written by BMJ investigations editor Deborah Cohen, offers a fascinating (and discouraging) look at how Big Food companies have enlisted the help of academic researchers, sports-medicine journals and professional sports organizations to create and market the science of hydration in a way that benefits their products’ sales.
Yes, the science of hydration.
“An investigation by the BMJ has found that companies have sponsored scientists, who have gone on to develop a whole area of science dedicated to hydration,” writes Cohen. “These same scientists advise influential sports medicine organizations, which have developed guidelines that have filtered down to everyday health advice.”
What those scientists have also done is “spread fear about the dangers of dehydration,” she writes.
[T]he sports drink industry needed to inculcate the idea that fluid intake was as critical for athletic performance as proper training. It became common for athletes to state that the reason why they ran poorly during a race was not because they had trained either too little or too much, but because they had dehydrated. This was a measure of the success of the industry in conditioning athletes to believe that what they drank during exercise was as important a determinant of their performance as their training.
Although research suggests that thirst is the most reliable indicator of dehydration for most people, including athletes, the sports drink industry, which began with Gatorade in the 1960s, came to realize they needed a different message, one that would sell more product. They had to persuade people that relying on thirst was not good enough to ward off the dangers of dehydration — and, even more to the point (or the industry’s bottom line), that relying on water wasn’t good enough, either.
To pull off this feat, sports-drinks companies turned to “selling the science” of hydration to consumers, says Cohen. They funded experts at various universities to conduct studies, and even set up their own research institutes, like the Gatorade Sports Science Institute (GSSI) in Barrington, Ill. They also exerted their influence in other ways, as Cohen notes:
In 1992, the American College of Sports Medicine — the “premier organization in sports medicine and exercise science” with over 45,000 members — accepted a $250,000 donation from Gatorade. Four years later, in 1996, the American College of Sports Medicine produced guidelines that adopted a “zero % dehydration” doctrine, advising athletes to “drink as much as tolerable.” This guidance grew out of a roundtable meeting in 1993 “supported” by Gatorade.” …
That 1996 guidance stood until 2007, when in updated guidance the college acknowledged that people should drink according to the dictates of thirst. [The big reason for this change was the growing number of marathon runners who were dying or becoming critically ill not because of drinking too little water (there are no documented deaths of marathon runners dying of dehydration), but because of drinking too much, which can lead to a life-threatening medical condition called hyponatraemia.] However, [the college] still promoted the idea that people should lose no more than 2% of body weight during exercise, and this remains the position in the published literature — although how people are meant to know how much weight they are losing while exercising isn’t made clear.
A web of financial ties
Many of the authors of the updated guidance had financial ties to the sports-drink industry, Cohen points out, as do many of the scientists publishing studies on these products in key sports medicine journals. Financial conflicts of interest also exist within the editorial boards of many of the journals in which these studies appear.
These links between sports medicine journals and the sports drink industry may help to explain a characteristic of the sports drinks literature that is familiar to those who have analysed drug trials over the past 30 years — the relative (or almost complete) absence of negative studies.
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.”
Cohen’s article is an eye-opener — as are all of the other papers in this remarkable series. And they are all available to read in full on the BMJ website — in plenty of time for the Olympics.