According to a recent sports survey, almost 60 per cent of US college athletes use nutritional supplements that are unregulated and may contain banned substances such as ephedrine.

The survey, released by the American National Collegiate Athletic Association (NCAA) this week, showed the use of amphetamines, anabolic steroids and ephedrine, while still low, has increased slightly in the past four years.

Gary Green, chairman of the NCAA's drug testing and drug education subcommittee, said most positive tests result from substances found in nutritional supplements. "You need to educate student-athletes about supplements from the time you start recruiting them," he said.

The NCAA said that only 15 per cent of those who took the supplements got them from a coach, nutritionist or doctor.

The survey tabulated responses from more than 21,0000 college athletes.