A runner in the London marathon has died after taking a dietary supplement. The Associated Press reported that Claire Squires, who had raised more than $1 million in donations, collapsed near the end of the marathon in April. A coroner said that the dietary supplement she took contributed to her heart failure.

The 30-year-old had taken a scoop of the supplement Jack3d in her water. The supplement contains a stimulant called DMAA or dimethylamylamine.

Coroner Philip Barlow said to the AP, DMAA ... on the balance of probabilities, in combination with extreme physical exertion, caused acute cardiac failure, which resulted in her death."

DMAA is a substance that is prohibited by the World-Anti-Doping Agency, reported The AP. Despite this, the substance was legal and easily found in Britain. It has since been banned due to its risks.

"My hope is that the coverage of this case and the events leading up to Claire's death will help publicize the potentially harmful effects of DMAA during extreme exertion," Barlow said to the BBC 

DMAA was first patented in 1944 as a nasal decongestant but the supplement has as of recently,  become popular as a fat loss and dietary supplement, reported The Independent.

"The substance is on the (WADA) banned list, but the only athletes to be tested would be elite athletes," London Marathon spokeswoman Nicola Okey said to The AP. "We just ask the rest of the runners to be medically fit. We don't make any other inquiries about what substances they are taking. We will be amending our medical advice following the inquest's verdict.

The affects of DMAA have been reported to be like caffeine.

"Popular among bodybuilders as well as endurance athletes the substance is outlawed by many professional and amateur sporting bodies. The deaths of two US servicemen during training led to renewed concerns. In April 2012 the United States Food and Drug Administration wrote to manufacturers including the makers of Jack3D noting that DMA caused blood vessels and arteries to narrow, raised blood pressure and possible heart attack. In August it was reclassified as a medicine in the UK," reported The Independent.