In the final stretch of the 26.2 miles of the London Marathon last April, 30-year-old runner Claire Squires collapsed and died. At an inquest Wednesday, Squires’ boyfriend Simon van Herrewege said she had included a scoop of the supplement Jack3d in her water bottle, which she intended to drink from if she felt her energy lagging.

“She said she was going to take one scoop, as recommended. In her own words: 'If I hit a bit of a wall, I might take this drink and see if it pushes me through the end of the marathon,'" van Herrewege said.

Jack3d contained the amphetamine-like stimulant DMAA (1,3-dimethylamylamine), which has been linked to psychiatric disorders, heart attacks and strokes.

Coroner Dr. Philip Barlow said Squires, “had taken a supplement containing DMAA which, on the balance of probabilities, in combination with extreme physical exertion, caused acute cardiac failure, which resulted in her death.”

Although banned now, DMAA was legal for sale at the time. Squires purchased the sports nutrition supplement — which was advertised as workout aid or a weight-loss supplement that boosted energy, concentration and metabolism — online.

In August 2012, the Food Standards Agency (FSA) advised people not to consume products containing the stimulant. It said DMAA could be fatal and linked it with high blood pressure, nausea, cerebral hemorrhage and stroke. DMAA is also listed on packaging as geranium extract, geranamine, methylhexanamine and 4-methylhexane-2-amine. DMAA was banned by the U.S. Army following the deaths of two soldiers who had taken it.

"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," said van Herrewege.

Squires, a hairdresser from North Kilworth, was running in memory of her brother and had aimed to raise $700 for charity with the run. Following her death, donations soared to more than $1.5 million in her name.

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London Marathon runner died after using supplement
Coroner says DMAA, which was in the Jack 3D she added to her water, was a factor in Claire Squires' cardiac failure.