Soccer's governing body FIFA is alarmed at the number of players taking food supplements and has warned of the risks of failing dope tests by taking non-approved products.
Chief medical officer Jiri Dvorak told FIFA's website (www.fifa.com) that around 35 percent of players at World Cup level were regularly taking food supplements, with that figure rising to almost 50 percent at under-17 and under-20 level.
Dvorak said that many players did not seek medical advice and risked failing doping tests as a result. "The marketing strategies of the producers of food supplements are influencing the behaviour of footballers and athletes in general," said Dvorak.
"From different surveys we know that about 60 percent of under-16 athletes in the US are using nutritional supplements daily and all of them believe they will increase their performance. This is definitely not based upon the scientific evidence or literature, which says the opposite."
Dvorak said he was both surprised and alarmed that athletes were not seeking specialist advice. "The same scientific studies also show that 70 percent of these young athletes do not seek adequate advice from a nutritional specialist physician, they just take it and believe it will improve their performance."
Dvorak also warned that players risked failing doping tests by taking supplements. "It is well established and proven that many of the food supplements are contaminated by prohibited substances such as anabolic steroids and other substances.