LONDON (Reuters) - Athletes arriving in Britain for the start of the London Olympics were given a stark reminder of the dangers of so-called nutritional supplements on Wednesday when UK Anti-Doping banned former cruiserweight world champion Enzo Maccarinelli. The agency said the Welsh boxer had been banned for six months after testing positive for Methylhexaneamine (MHA) following a fight in March. Methylhexaneamine, a product which is claimed to promote mental and physical performance and aid weight loss, can be found in several nutritional supplements and is sometimes known as the rather harmless sounding geranium derivative. UK Anti-Doping chief executive Andy Parkinson said Maccarinelli's violation was a reminder of the country's tough stance on doping ahead of the Games. "This is a timely reminder that, no matter what your sport, under the principle of strict liability athletes must exercise extreme caution over what they put into their body," he said. With this in mind, Olympic athletes should be aware that they are now in-competition from 16 July until 12 August and could be tested at anytime, anywhere. "MHA is available in a range of supplement products, is banned in-competition, and can often be listed under a number of different names," he added. Maccarinelli once held both the WBU and WBO versions of the cruiserweight title but his career suffered a setback when he was stopped by David Haye in London in 2008. He tested positive for methylhexaneamine after winning the British cruiserweight title against Shane McPhilbin in March. "UK Anti-Doping continues to work closely with the British Boxing Board of Control to maintain the integrity of the sport," the statement added. As a professional, Maccarinelli had not been eligible for the Olympics.