The DFA warned against Jack3d, once the most popular DMAA (1,3-dimethylamylamine/methylhexaneamine)-based supplement, but was reformulated with out DMAA by Texan manufacturer USPlabs in 2013.
DMAA was largely banned in 2012 by many European and other countries after it was linked to health problems. There were also issues surrounding its geranium sourcing claims.
Yet DMAA remains on sale on websites like Alibaba and e-Bay and it can be found for sale via a simple Google search.
"It is the sad reality that DMAA is widely available - just one company selling DMAA is one company too many. DMAA is a banned substance and has no place in legitimate sports nutrition products," said Dr Adam Carey, chair of European Specialist Sports Nutrition Alliance (ESSNA).
"While the majority of the industry complies with this, there are unfortunately some unscrupulous retailers, particularly those selling sports nutrition online that tend to come from outside the EU, who do not follow the law and continue to market this unlicensed medicine as sports nutrition. So we urge all sportspeople to please ensure they're only buying their sports supplements from responsible and reputable retailers, and to always check their ingredients' list".
DMAA-related adverse events have included increased heart rate, irregular heartbeat, high blood pressure, blood clots, stroke and death.
Dr Luca Bucchini, managing director at Hylobates Consulting in Italy, said "As for consumers, i think they should know that DMAA is not like other substances in supplements: DMAA is not safe. You can't predict whether you have the make-up that will make DMAA seriously dangerous for you; you can't predict that the training will, on a certain day, turn out to be hard enough, or the climate hot enough, for DMAA to put your life at risk. Brain hemorrhage is no joke, and it has happened to DMAA users".
The EU food law expert said DMAA products found by the Danes could be leftovers from earlier batches made by USPlabs. There have also been cases where fake Jack3d and other pre-workout supplements have been manufactured illegally by fly-by-night pirates.
The news comes as UK medicines regulator, the Medicines and Healthcare products Regulatory Agency (MHRA), recently launched a week long education campaign to educate people and enforce compliance regarding the substance.
The stimulant is prohibited by the World Anti-Doping Agency (WADA) and has been responsible for 100s of doping infringements since 2008.
Just last week the Jamaican sprinter Nesta Carter had a 4x100m gold medal from the 2008 Beijing Olympaid stripped from him by the International Olympic Committee (IOC) after retrospective testing found DMAA in his sample. The whole Jamaican team, including triple Olympic 100m and 200m champion Usain Bolt, was stripped of its gold medal.
"From an industry perspective, DMAA is very bad," Dr Bucchini said. "It damages athletes, as in the case of Usain Bolt, which are role-models for many consumers."
He added: "If it is used somewhere in the supply chain, it may cross-contact legitimate supplements; even tiny amounts can result in a positive doping test, and again the industry suffers. More fundamentally, I think consumers of sports nutrition products need to know that products they buy are safe, and they do not have to worry about safety or positive doping results. That's an interest for the whole industry."