The American Beverage Association (ABA) has lashed out at the British Medical Journal (BMJ) for a critical article series on sports drinks, and said the journal showed bias in overlooking 'widely accepted' research thereon.
The ABA hit back at the six articles published on July 19, saying: "Furthermore, suggesting that industry-funded nutrition-related scientific studies may bias conclusions fails to look at the merits of the science in those studies and disregards the integrity of the peer-review process enforced by the highly regarded scientific journals."
Hydration was essential for good health, the ABA said, adding that "science clearly shows that the water, carbohydrates and electrolytes in sports drinks provide significant hydration and athletic performance benefits.
"Furthermore, our member companies' marketing makes it clear that these functional beverages are formulated for athletes and those who are physically active," the trade body added.
That said, sports drinks were also an option for consumers working out, training, exposed to high temperatures or simply seeking refreshment within the context of an active and healthy lifestyle, the ABA said.
'The Truth about Sports Drinks'
On July 19, just prior to the Olympic Games, the British Medical Journal (BMJ) published six controversial articles exploring the science of sports drinks.
In a lead feature summarising the BMJ's research conclusions, 'The Truth about Sports Drinks', investigations editor Deborah Cohen noted that sports drinks had the might of multinationals (many of whom are ABA members) behind them.
She cited the likes of PepsiCo (Gatorade), Coca-Cola (Powerade) and Lucozade (GlaxoSmithKline, GSK), companies Cohen said also backed sports medicine organisations.
Cohen said that one of the greatest successes of PepsiCo's Gatorade Sports Science Institute (GSSI) was to "undermine the idea that the body has a perfectly good homeostatic mechanism for detecting and responding to dehydration: thirst".
She then juxtaposed this comment by quoting Bob Murray, former GSSI director, in 2008: "Unfortunately, there is no clear physiological signal that dehydration is occurring."
According to Cohen, academics with links to industry promoted the dangers of dehydration to athletes and water's insufficiency vis-a-vis sports drinks for rehydration, with the message filtering through to the medical profession (the UK National Health Service, for instance) and schools.
But quoting Professor Tim Noakes from Cape Town University, to the extent that dehydration during exercise was not life threatening, Cohen said that, conversely, exercise-related hyponatremia (lack of sodium in body fluids outside cells) was the real concern.
The largest prospective study on marathon runners for the New England Journal of Medicine (Almond et al. 2005) found no association between hyponatremia and composition of fluids drunk, and concluded that fluid volume was the main causative factor, she said.
But while, firms such as Coca-Cola (Powerade) acknowledged hyponatraemia as a cause for concern for "anyone doing endurance sports" , they had linked it to a failure to replace sodium lost through sweat, or to drinking a very large volume of low-sodium beverages such as water, she said.
"The Powerade webpage describing hyponatraemia does not mention that it can also happen if sports drinks are consumed," Cohen said, before adding that the brand had since updated its website to clarify that athletes should not over-consume any type of liquid.
Cohen then moved on to hydration claims for sports drinks, which she explained were based upon sodium stimulating thirst, leading to higher fluid consumption with better retention than water (due to carbohydrates in sports drinks aiding intestinal water absorption).
Coca-Cola, GSK and PepsiCo insisted that the scientific evidence supported their case, as did the European Food Safety Authority (EFSA) in an opinion accepting two health claims relating to carbohydrate-electrolyte solutions , Cohen said, work the BMJ also took issue with in another July 19 paper.
Poorly designed research alleged
The EFSA-accepted claims are that such solutions: (1) enhance water absorption during exercise, and (2) help maintain endurance performance relative to plain water.
Cohen said that, on behalf of the BMJ, three Oxford University academics assessed the evidence behind Lucozade based upon 106 studies conducted between 1971 and 2012, since GSK was the only firm to reply to a request for full links to studies (other major firms did not supply full bibliographies).
"An accompanying analysis of the studies found that the quality of the evidence was so poor that it was impossible to draw firm conclusions about the effects of the sports drink [Lucozade]" Cohen said.
Discussing the Lucozade science in their separate BMJ paper, the Oxford academics objected to what they said were small sample sizes (limiting result applicability), poorly designed research and 'data dredging' (with failure to define outcome measures prior to studies).
Biological outcomes - such as reductions in muscle glycogen use - did not necessarily correlate with improved athletic performance, as claimed, the scientists asserted, while they also slammed studies that lacked blinding.
Noting the relative absence of negative studies on the role of sports drinks in hydration, Cohen said several sources told the BMJ that it was difficult to get such papers published, with one, Paul Laursen from New Zealand's Sports Performance Institute, citing "spurious reasons".
Speaking to our sister site NutraIngredients.com , GSK noted 40+ years of clinical research and 85 studies that lent support to winning EFSA claims.
Maria Potter, GSK communications director at Consumer Healthcare Great Britain & Ireland said that consumers trusted the science behind the firm's claims and always listened carefully to scientific feedback, including those who disagreed with its claims.
"We would, of course, be happy to meet with the BMJ and the Centre for Evidence based Medicine [at Oxford] to understand their position," she said.