A healthy and fit woman who collapsed during the London Marathon had taken a performance-enhancing drug, an inquest has heard.
Claire Squires collapsed in Birdcage Walk, a mile from the finish line in the 26.2 mile event, on 22 April last year.
Claire was raising money in memory of her dead brother
Miss Squires, 30, a regular runner who had completed the London Marathon two years previously, had aimed to raise £500 for The Samaritans but the total jumped to more than £1 million following a public outpouring of support in the aftermath of her death.
She had bought a supplement called Jack3D containing a substance called DMAA, which increases the heart rate, Southwark Coroner's Court was told.
She had a scoop of it in her water bottle, according to her boyfriend Simon van Herrewege.
He told the inquest: "Claire ended up getting a tub of this supplement Jack3D to give you a bit of an energy boost. It is a bit like caffeine.
"Claire never really got on with it. She never really liked it.
"She said she would take one scoop in her water bottle.
"She said that if 'I hit a bit of wall I will take it'."
The supplement is still being sold on Amazon but the DMAA has been taken out of it, the court heard.
Coroner Dr Philip Barlow said he hoped the case would highlight the potential dangers of DMAA.
He said: "My hope is that the coverage of this case and the events leading up to Claire's death will help publicise the potentially harmful effects of DMAA during extreme exertion."
Turning to the family, who had sat and listened quietly throughout the hearing, he said: "She was obviously a very dedicated and well motivated person. She died raising money for charity.
"I can only offer my condolences to all members of the family for a very tragic loss of an obviously dear person."