The benefits of a mother's milk for her offspring have long been known, but Australian researchers say it can also deliver significant gains for athletes. An eight-week study of 40 athletes showed those who had taken daily doses of cow colostrum - the secretion in the first days after birth that boosts an infant's immune system - had more stamina than others on a protein placebo.

And they believe athletes using the substance cannot be accused of doping because it is a natural food product with no known side-effects. While those taking colostrum did not perform better than the others in the first half of tough two-stage training sessions, they came back 20 per cent better after a short break.

"They ran for longer, covered greater distance and did more work," says exercise physiologist Jon Buckley, project leader from the University of South Australia. He sees obvious benefits for stamina sports like soccer and Australian Rules football which have breaks in the game. "You will recover better in the breaks, so you will work harder in the second half," he says. Another study by the university showed preliminary benefits in building muscle mass and reducing body fat when the intake of colostrum is combined with a weight-training programme for athletes in power sports such as discus, shot putt and sprinting. Buckley says there is also potential for the natural substance to help general weight loss and to treat sufferers of the debilitating chronic fatigue syndrome.

"Those on colostrum just generally felt better and less fatigued from training," he says.

Sports authorities are likely to closely examine colostrum and its effects, but Buckley does not see any reason why it should be banned. "It is not a performance enhancer, per se. By definition it is a food supplement. It is milk, it is not a drug."