18 July 2012 - BMJ - Striking lack of evidence to back up claims for popular sports brands

The investigation reveals new research carried out by the Oxford Centre for Evidence Based Medicine and the BMJ, and published in the online journal BMJ Open. It concludes that no sound evidence could be found to support claims made by some of sport’s biggest brands and that it is “virtually impossible for the public to make informed choices about the benefits and harms of advertised sports products.”

The findings are also highly critical of the methods used by the European Food Safety Authority (EFSA) to regulate these marketing claims. Dr Matthew Thompson, Senior Clinical Scientist at Oxford University’s Department of Primary Health Care Sciences, told the Panorama investigation these methods are based on “very meagre” research, supplied largely by manufacturers themselves. He would like to see “a more scientific and rigorous approach” to assessing the basis of food claims in Europe.

Their findings are part of a joint investigation by the BMJ and BBC Panorama which tests the science behind the marketing hype of this multibillion-dollar industry and suggests we could be wasting our money on these products.

Full details will be published on bmj.com and broadcast on Panorama “The Truth About Sports Products” on Thursday 19 July at 8pm on BBC One.

The investigation also explores the role of sports drinks companies in the “science of hydration” and questions their links with some of the world’s most influential sports bodies in a bid to gain public trust in their products and persuade ordinary people they need more than water when they exercise.

But Arthur Siegel, Associate Professor of Medicine at Harvard University, says we are being misled about the dangers of dehydration and industry advice to “stay ahead of thirst” when, in fact, drinking too much of any liquid can be fatal.

A team at Oxford University tested the evidence behind 431 performance-enhancing claims in adverts for 104 different sports products including sports drinks, protein shakes and trainers.

If the evidence wasn’t clear from the ads, they contacted the companies for more information. Some, like Puma, did not provide any evidence, while others like GlaxoSmithKline – makers of Lucozade Sport – provided 174 studies.

Yet 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. They say this absence of high-quality evidence is “worrying” and call for better research in this area to help inform decisions.

Many top sports scientists support this view. Professor Tim Noakes from the University of Cape Town says that while sports drinks may be helpful for elite athletes, the drinks companies rarely study ordinary gym goers. Many also contain high levels of sugar.

Yet sports drinks like Lucozade, made by GlaxoSmithKline, and Powerade, made by Coca Cola - the official drink of the 2012 Olympics - are sold in supermarkets and will soon have the European stamp of approval that they “help maintain endurance performance.”

GlaxoSmithKline also runs a school science programme, aimed at 11-14 year olds, looking at things like the advantages of sports drinks over water, as part of its involvement in the Olympic anti-doping operations.

Dr Matthew Thompson from the Oxford team is also concerned about rising levels of obesity among children and young people. He says anything that suggests sports drinks are good for us “could completely counteract exercising more, playing football more, going to the gym more.”

But not only is industry telling us we need specially formulated drinks to exercise, it is also telling us how to drink, with advice like “stay ahead of your thirst” when the evidence suggests it’s best to drink when you’re thirsty.

Some manufacturers have even suggested that sports drinks can protect against the effects of hyponatremia (a drop in the body's salt levels caused by over-drinking) when experts are clear that drinking too much of any liquid can be dangerous.

The Oxford team were also unable to find good quality evidence to support claims that special trainers reduce injury, although for decades the industry focus has been on creating specialised shoes which aim to reduce the risk of injury by cushioning against impact and controlling pronation – guidance which the NHS supports.

Sports injury expert, Professor Irene Davis of Harvard University argues that “there is no evidence for prescribing tailored footwear”. This view is supported by evidence from a recent study by the US military – the biggest sports footwear study of its kind. Soldiers were divided into two groups – one of which was prescribed neutral shoes and the other received shoes tailored for their feet. “They found absolutely no difference between the groups in terms of injury patterns”, says Professor Davis.

Benno Nigg, a leading expert in the biomechanics of running shoes who has worked with the major sports brands for over four decades, also told Panorama that his recent research confirms that “the most important predictors for injuries are distance, recovery time, intensity and those type of things.” Shoes, he says, are “minor contributors.”

Similarly, Carl Heneghan, who led the research team at Oxford Univeristy found “no evidence” to support claims that protein shakes or supplements boost performance and recovery any more so than eating a diet that’s rich in protein and carbohydrates. Nutritionist, Professor Mike Lean describes protein shakes as “a rather expensive way of getting a bit of milk.”

“These misleading messages filter down to everyday health advice by company-sponsored scientists who advise high-profile sports bodies,” explains Deborah Cohen, BMJ Investigations Editor. “For instance, fear about the dangers of dehydration has become gospel and now influences what and how we drink when we exercise. It’s a triumph of marketing over science.”

The investigation concludes: “For now, the evidence we do have seems to be leading us to a rather common sense and affordable solution. Eat a well balanced diet, drink water, find some comfy shoes, and get out there and exercise regularly.”