Regulators have raised concerns over a range of dangerous steroids, stimulants and hormones that are increasingly finding their way into fitness supplements in the wake of the inquest into the death of 30-year-old runner Claire Squires during last year's London Marathon.
It later emerged that the stimulant, DMAA, that contributed to her death was still legally on sale from overseas websites despite being banned for sale in the UK four months after she died. Now, the Medicines and Healthcare products Regulatory Agency (MHRA) has highlighted the potential dangers of a range of other ingredients that should only be available on prescription but are increasingly found in unlicensed fitness supplements.
Meanwhile, anti-doping experts have also warned of the dangers of amateur athletes reaching for apparently safe supplements, which are increasingly an accepted part of the culture around running and gym-going, without realising what is in them or the dangers of potential side effects.
The MHRA, an executive agency of the Department of Health, said it was also concerned about supplements containing the stimulants ephedrine, synephrine and yohimbine, which have been linked with side effects such as kidney failures, seizures and heart complications.
All claim to give a similar energy boost and "focus" as the DMAA found in the Jack3d powdered supplement that Squires added to her water and was found to be a key factor in her death from a heart attack, one mile from the finish line.
Unlike DMAA, these ingredients can be sold in licensed medicines, but the MHRA is concerned as they are increasingly being found in sports supplements – and so there is no control over the dosage contained or quality.
An MHRA investigation this year found that 127 illegal products including energy and muscle-gain supplements were being sold containing dangerous steroids, stimulants and hormones.
But the MHRA only has the ability to take action against retailers selling unlicensed products in the UK, where they can be ordered to remove them from their shelves. Products sold into the UK from websites outside Europe cannot be regulated.
According to anti-doping officials, concerns have escalated in recent years as the range of supplements available on the internet has grown and the culture surrounding them has changed. While there is a big difference physiologically between taking perfectly safe nutritional supplements and the stimulants available online, some fear that the lines have become blurred for some amateurs.
"Because it appears so normal it is very easy for the amateur athlete to pick something that appears to suit their need. There are products out there that can make a difference to performance," said Dr Ken van Someren, director of sports science at the English Institute of Sport.
"The real challenges come for the amateur athlete, who doesn't have someone pointing out which products are safe and which aren't or someone able to cut through the performance claims. It is an industry that is still relatively unregulated."
Graham Arthur, legal director at UK Anti-Doping, said a combination of the unlicensed trade in internet supplements and the extent to which supplements had become an established part of training programmes had increased the risks for recreational athletes. In recent years, there has also been a surge in the popularity of marathons and half-marathons, as well as triathlons and cycling sportives, with more recreational athletes taking up running and cycling.
"We regulate the elite athlete community. But the same behaviour and motivations also apply to the big community of recreational athletes. This lady's story is very familiar," said Arthur. "They take up a sport, get better at it, they read forums or talk to other athletes. It is impossible to distinguish the dangerous stuff from the bland stuff sometimes. Awareness and education is everything."
He said that the use of supplements was "an established and entrenched part of sports medicine" but urged caution among amateur athletes looking to emulate their sporting heroes.
"Any elite athlete will have a supplement plan provided by their club or coach. I can ape the sports stars I admire by buying the same kit or using the same equipment. A logical extension of that is if you learn certain athletes use supplements, you'll do the same," he said.
"What's missing is the recognition that supplements need to be approached with some caution. You make an informed choice about the supplements you use. There is a balance there. There's no point telling people to avoid supplements, but if you're going to use them approach them in a sensible way."
Educating recreational athletes about the dangers was made more difficult by the "thesaurus of names" that substances and supplements went under, especially in the unlicensed online market, said Arthur. The ingredient that the makers of Jack3d used to replace DMAA once it was placed on the MHRA controlled list is also on the World Anti-Doping Agency (Wada) banned list.
"Some of them are homemade and others are made who knows where. Ephedrine raises your core temperature and if you have too much of it you basically cook from the inside," said Arthur.
"ECA (Ephedrine, caffeine, aspirin) stackers are used by the recreational athlete community – cyclists, runners, gym goers. They are easy to get hold of, they give you a boost and they promise to keep the weight off."
He said he was also concerned about the "escalator effect" of athletes using caffeine pills such as Pro Plus or drinking cans of Red Bull before exercise and then seeking stronger, and potentially dangerous, products to achieve a more pronounced effect.
UKAD is lobbying for substances such as DMAA, which is forbidden for use in competition by elite athletes but allowed out of competition, to be banned outright by Wada for the sake of clarity.
A string of athletes, including Manchester City defender Kolo Touré, have been banned after testing positive for DMAA (also known as Methylhexaneamine or 1,3-dimethylamylamine).
In some cases, such as that of Simon Mensing, a former member of Scottish football team Hamilton, the positive test was blamed on contaminated supplements that had claimed to contain no banned ingredients. Touré tested positive after taking diet pills belonging to his wife.
Van Someren said there was little excuse for elite athletes to get caught out, because every supplement could be cross checked to ensure it contained ingredients that were not on the Wada-banned list and had not been contaminated.
"The elite population probably have it a lot easier. We have qualified dieticians and nutritionists that work with them, looking at the demands and the performance needs. We start looking at how much supplements help from a performance perspective or a nutritional perspective," he said.
"For the amateurs, it's education. If there is one good thing to come from this case, it is that it does put it in the spotlight and the headlines."
