The sports drink industry makes millions of pounds from selling drinks and other supplements to people who want to increase their energy and stamina while exercising.
But when scientists reviewed the effects of the supplements they found they offered no more benefits than the protein found in a normal balanced diet.
Dr James Betts from the Department reviewed the results of all existing research into the effects of supplements containing carbohydrate and protein.
He said: "While many carbohydrate drinks are often appropriate for individuals keen to enhance their performance, claims that protein can be of similar benefit are simply not supported by firm scientific evidence.
"Aside from these proposed effects during exercise, many supplement manufacturers claim that supplementing our diets with added protein may help the body to adapt to physical training. Protein is of course an essential part of our diets but even athletes who are training hard will almost certainly get more than enough protein from the food they eat."
Dr Betts' review of the available evidence, due for publication in the current issue of Medicine & Science in Sport & Exercise, identifies that much of the research into these supplements has been conducted on people in the morning who have not been allowed to eat anything for a number of hours, so food in any form might be expected to be beneficial.
He said: "There is a need for more evidence showing whether these supplements can be useful under ‘real-world’ conditions, such as following exercise later in the day when usual meals will have already provided the necessary nutrients."
Dr Betts said that people considering the use of such supplements should be aware of the strength of evidence supporting the desired effects and that this should be balanced against the possible risks.
He said: "An analysis of around 600 over-the-counter nutritional supplements was conducted a few years ago and it was found that 10-20 per cent were contaminated with anabolic hormones not stated on the label, mostly testosterone and nadrolone, with supplements purchased on the UK market at the upper end of this range (19 per cent).This alone suggests that the decision about whether or not to consume any supplements requires an evidence-based risk-benefit approach and we should not be surprised if any personal experimentation results in muscle gain which could be entirely unrelated to the listed ingredients."