July 20th, 2012

The BMJ’s Amazing Shock and Awe Assault on Sport Drink Science

CardioExchange welcomes this guest post by Yoni Freedhoff, an assistant professor at the University of Ottawa and founder of Ottawa’s Bariatric Medical Institute. This piece originally appeared on his blog, Weighty Matters.


Wow, WOw, WOW!

What words would you use when one of the world’s most prominent medical journals publishes not just one article critical of a specific category of food, but seven such articles, and those articles conclude that the food is being marketed on the basis of food-industry-funded hype and collusion?

I’d use the words, “Thank You!”

You’ll definitely hear about it in the news today as the British Medical Journal has seven incendiary pieces that are highly critical of sport and energy drinks, their Big Food parents, and the researchers that are conflicted by them.

The first piece (The evidence underpinning sports performance products: a systematic assessment) has researchers analyzing sport-drink advertising and identifying an astonishing 431 performance-enhancing claims for 104 different products. Those claims were “backed up” by references made on the products’ websites to 146 references. Of those 146, the authors could only find half of them. Of that half:

“84% were judged to be at high risk of bias”,

while only three were deemed to be of high quality and of low risk of bias. Ultimately, the authors — not surprisingly — concluded that:

“The current evidence is not of sufficient quality to inform the public about the benefits and harms of sports products.”

In the next article (The truth about sports drinks), BMJ‘s Investigations Editor Deborah Cohen explores the funding and financial ties between sports drinks’ parent Big Food companies, professional sport organizations, and expert advisory panels. Her hard-hitting piece is absolutely fascinating and covers how sport-drink-friendly messaging evolved and later became questionably incorporated into official medical and sport recommendations, often by advisory boards with multiple members on sport-drink payrolls.

Then, the BMJ tackles the European Food Safety Authority’s criteria for sport-drink claims (How valid is the EFSA’s assessment of sports drinks?). The authors were highly critical of the two claims approved by the EFSA: that sport drinks “improved water absorption during exercise” and that they helped with “maintenance of endurance performance.” They state that the EFSA asked Big Food to supply the references upon which their decision was based, that they had no formal criteria to evaluate which studies warranted inclusion in the analysis (Big Food submitted non-peer-reviewed book chapters, opinion pieces, etc.), and that, of those studies supplied to the EFSA, many were absent methodologies.

For the “improved water absorption during exercise” claim, the authors combed through the only 22 scientific studies presented to the EFSA and concluded that 17 were of poor quality, the subjects were predominantly male, only 3 studies included people over the age of 30, and not one had an outcome that included performance in a race or a sporting event.

For the “maintenance of endurance” claim, there were 26 scientific studies of which 19 were deemed to be of poor quality, 89% of the subjects were men, 73% of the subjects were endurance-trained men, 65% of subjects were endurance-trained men between the ages of 20 and 30, and only one study measured performance in a race setting.

The next explosion comes from Tim Noakes, the Discovery Health Chair of Exercise and Sport Science from the University of Capetown, in a commentary (Role of hydration in health and exercise) that can succinctly be summarized as: If you get thirsty you should drink and that over-hydration is a much more common and dangerous risk to the athlete than is dehydration.

Next up is an analysis of the science behind the GSK sport drink Lucozade’s claims that it boosts performance (Forty years of sports performance research and little insight gained). The authors’ conclusion says it all:

“From our analysis of the current evidence, we conclude that over prolonged periods carbohydrate ingestion can improve exercise performance, but consuming large amounts is not a good strategy particularly at low and moderate exercise intensities and in exercise lasting less than 90 minutes. There was no substantial evidence to suggest that liquid is any better than solid carbohydrate intake and there were no studies in children. Given the high sugar content and the propensity to dental erosions children should be discouraged from using sports drinks.”

And there’s still more!

Authors explore the marketing of sport drinks through social media and user endorsements (Miracle pills and fireproof trainers: user endorsement in social media). Not surprisingly, Big Food are savvy marketers, and Facebook and Twitter let them get away with making claims that even the EFSA would frown upon. Basically what companies do is try to encourage “user-generated content” which in turn they can then claim they didn’t actually write.

With the seventh article comes mythbusting (Mythbusting sports and exercise products). Among the busted myths:

  • The colour of urine accurately reflects hydration (nope)
  • You should drink before you feel thirsty (nope)
  • Energy drinks with caffeine or other compounds improve sports performance (nothing other than equivocal benefit from caffeine)
  • Carbohydrate and protein combinations improve post-workout performance and recovery (nope)
  • Branched chain amino acids improve performance or recovery after exercise (subjectively did help, objectively equivocal)
  • Compression garments improve performance or enhance recovery (performance, probably not; recovery, yes)

Finally, there is a commentary on how to stay hydrated (To drink or not to drink recommendations: the evidence). The 4 conclusions?

  1. There’s a wide range of hydration within which our amazing bodies work wonderfully.
  2. Freely chosen rates of fluid intake among elite athletes match sport-body recommendations (0.4-0.8 litres per hour).
  3. Intake at rates higher than sport-body recommendations confer no advantages.
  4. Athletes who lose the most body mass during marathon, ultra-marathon, or Ironman races do the best.

These articles are all unbelievably important, both in regard to the recommendations we give ourselves and our children and as to how unwise it is to let Big Food push an agenda.  They are not our friend.

Huge props to the BMJ and their investigative partner BBC Panorama for this groundbreaking series.

2 Responses to “The BMJ’s Amazing Shock and Awe Assault on Sport Drink Science”

  1. Robin Motz, M.D., Ph.D. says:

    The NaCl concentration of sweat is approximately equal to a 50-50 mix of Gatorade and water. When I play tennis, I drink equally from both bottles, about two quarts of fluid in two hours of singles. I have patients who get fatigued and dizzy by the 13th hole of a golf course on a hot day because drinking too much water when you get thirsty from sweating easily dilutes your blood salt concentration and thereby drops your blood pressure. And older patients respond more poorly to drops in the sodium content of their blood. Of course athletes responding to thirst will replace what they lose in water, but where will they get the salt? Has anyone done stamina tests on athletes drinking only water vs. water plus salt replenishment? This would be an easy clinical study to do, checking for orthostasis after an hour of hard exercise under both replacements.

  2. Leon Hyman, Ms M.D. says:

    Thirst is usually not perceived until 0ne is at least 1.5 liters of fluid depleted. If you wait till you are thirsty to drink on a hot day and are still competing, then it can be very difficult to even partially catch up. I start drinking water early but supply salt via a few pistachios, or a few baked potato chips. Sunflower seeds are great as long as you don’t mind spiting. In senior citizens, dehydration should be avoided because of clinical or hidden vascular disease that might be there