They claim to increase energy levels and help you exercise better.
But specialist sports drinks are a waste of money and could actually be harmful, say researchers.
They warn that rather than being beneficial to our health, popular brands such as Lucozade and Powerade contain large amounts of sugar and calories which encourage weight gain.
The academics from Oxford and Harvard universities also accuse the manufacturers of ‘misleading’ gym-goers by convincing them they are on the verge of dehydration.
They point out it is probably more dangerous to drink too much liquid because it can cause the deadly condition hypernatremia, where brain cells swell up.
The sports drinks market in Britain rose 10 per cent last year to more than £1billion. Around 440million litres of products are drunk annually – enough to fill 400 Olympic-sized swimming pools.
Although the drinks are marketed at gym-goers, they are also bought by office workers who just want an energy boost.
The study published in the British Medical Journal looked at 104 products, including sports drinks, protein shakes and trainers, and studied more than 400 health claims made in adverts.
In one 1997 advert for Lucozade Sport, footballer Alan Shearer is seen saying the drink is ‘designed for top athletes’. He adds: ‘It delivers fluid and energy fast so I’m always on top of my game.’
Energy drinks
In 1985, former Olympic gold medallist Daley Thompson endorsed Lucozade. A TV advert showed him drinking a bottle as he waited for traffic lights to change before sprinting off.
In another, Manchester United’s Wayne Rooney is seen drinking Powerade and is shown scoring a goal against his body double, who has only drunk water.
The researchers warned that, despite such claims, there is a ‘striking lack of evidence’ the drinks do any good.
Deborah Cohen, investigations editor at the BMJ, said: ‘These misleading messages filter down to everyday health advice by company-sponsored scientists who advise high-profile sports bodies.
‘For instance, fear about dehydration has become gospel and influences what we drink when we exercise. It’s a triumph of marketing over science.’
The authors also warned that protein-shakes are no better than drinking milk.
Their study, to be shown tonight on BBC1′s Panorama, concluded: ‘There is a striking lack of evidence to support the majority of… claims related to enhanced performance or recovery. The absence of high-quality evidence is worrying.’
A spokesman for GlaxoSmith-Kline, which makes Lucozade, said: ‘More than 40 years of research and 85 peer-reviewed studies have supported the development of Lucozade Sport and all our claims are based on scientific evidence that has been reviewed by the European Food Safety Authority.’
Coca-Cola, which makes Powerade, said: ‘Sports drinks are among the best-researched beverages in the world. There is a wealth of scientific research that can be relied upon.’
