As the dust settles on the latest doping scandal in athletics after two of the world’s fastest men failed drugs tests, why do athletes continue to use supplements?
Athletics is still reeling from the news that sprinters Tyson Gay and Asafa Powell tested positive for illegal substances. America’s Gay said he was "let down" after putting his trust in someone else, and Jamaica’s Powell has denied any intent to cheat, claiming he unknowingly ingested a stimulant via an over-the-counter supplement.
So how do top level athletes navigate the murky area of what constitutes a legal substance?
"I think it is very hard. One thing I would say is stay away from people who offer supplements that are supposed to change your hormone levels. That is a very grey area," says US Olympic gold medallist Lauryn Williams.
Most athletes I know trust that their coach or nutritionist are providing something clean and safe and have done the due diligence on their behalf. Just like sex, the only way to be sure is to abstain
"Most athletes I know trust that their coach or nutritionist are providing something clean and safe and have done the due diligence on their behalf.
"Just like sex, the only way to be sure is to abstain."
The 29-year-old sprinter, who is planning to hang up her running shoes at the end of this season, is one of the small minority of athletes who has taken a hard line against the use of supplements.
"Because I am unable to decipher the difference and unwilling to place my trust in someone else to do it on my behalf," she continues.
"Bearing in mind Tyson Gay said he put his faith in someone. The athlete always ends up taking 100 per cent of the responsibility as they are the performer and more has to be done to help athletes decipher for themselves what is or is not ok.
"I think it is the responsibility of the whole team to know and research what an athlete is taking. It does affect the reputation of all associated, in the long run."
The World Anti-Doping Agency (WADA) operates a strict liability code, where the athlete is 100 per cent responsible for any illegal substance found in their body. So Williams is not prepared to risk her career on the advice of someone else.
She took the decision to avoid any form of supplement, including vitamin pills, whey protein, and creatine or even fish oil.
"I am not sure how much benefit you get but, I would say the increase in performance is small and that other variables are equally as important, such as training conditions, nutrition and coaching."
This choice has not harmed the world champion’s career. The 5 feet 3 inch, 127 pound powerhouse, took home a gold medal in the Women’s 4 x 100 relay at the last Olympic Games in London and smashed the world record with the help of her teammates.
But there’s no doubt this multi-billion dollar industry does play a vital role in maximising an athlete’s performance.
Especially at the highest echelons of sport, where medals are determined by the smallest of margins; the right supplements combined with the right training plan can mean the difference between gold and silver.
"We ensure that all supplements given to our athletes are batch-tested," advises world-renown coach Stuart McMillan, who has worked with the likes of Greg Rutherford, Dwain Chambers and Christian Malcolm.
"If the athlete is maximizing his or her nutritional plan, typical supplements that I would recommend include high-quality protein powder and Amino Acid formulations, greens supplements, fish oil, and various cortisol modulators."
McMillan, who is performance director at the World Athletics Center, admits there is no such thing as "WADA-approved" supplements.
The organisation is not involved in the testing of any supplements or regulating the industry. It merely provides a list of prohibited substances for athletes to avoid. Supplement companies can market their products as tested clean through independent companies such as HFL and TRU. However, it remains very much an uncertain area, and Williams is calling for more guidance from WADA and governing bodies.
"I believe more education would be helpful in weeding out business people who are marketing supplements to athletes and an approved set of supplements should be available," she adds.
McMillan, who has spent the last month in Europe with US and British pole vaulters Brad Walker and Steve Lewis, is under no illusion as to what WADA can do with its "limited staff and budget".
"The onus is on national governing bodies, and their Olympic Associations to educate their athletes sufficiently about the possible dangers of supplements. Canada, the United States, and the United Kingdom are the vanguard in this - and it up to other countries to catch up."
"The final responsibility always lies with the athlete. It is imperative that the athlete has a well-trusted and well-educated group of advisors that can aid in any decisions."
Although WADA currently operates a strict code of liability, if new proposals are ratified, those behind the athlete, such as coaches and physiotherapists, will be the firing line when punishments are handed out from 2015 onwards.
Samrana Hussain is a freelance journalist who writes on international sport and news. She has covered three Olympic Games including Beijing 2008, London 2012 and numerous other global sporting events.
Follow her on Twitter @SamranaH