A now-banned drug in a sports nutrition supplement was a factor in the death of a runner during the London Marathon, a coroner has ruled.
Claire Squires, 30, of Leicestershire, collapsed and died on the final stretch of the 26.2-mile course last April.
The inquest heard the drug DMAA, found in some nutrition supplements and not banned at the time, was in her system.
The coroner said she died of cardiac failure caused by extreme exertion, complicated by DMAA toxicity.
Her boyfriend said she had put a scoop of a product containing DMAA into her water bottle.
Recording a narrative verdict at the hearing at Southwark Coroners' Court, Dr Philip Barlow said: "Claire Squires collapsed during the final stages of the London Marathon.
"She 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.
"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."
He offered his condolences to her family "for a very tragic loss of an obviously dear person".
Miss Squires, a hairdresser from North Kilworth, aimed to raise £500 for the Samaritans, but her death led to donations totalling more than £1m.
'Bit like caffeine'
DMAA (1,3-dimethylamylamine), which increases the heart rate, was being sold in the UK at the time in some sports nutrition supplements.
In August last year, the Medicines and Healthcare Products Regulatory Agency ruled DMAA was an unlicensed medicinal product.
It said all products containing DMAA needed to be removed from the UK market due to concerns about potential risks to public safety.
Miss Squires' boyfriend Simon van Herrewege said she had put a scoop of sports supplement Jack3D, containing DMAA, into her water bottle before setting off on the race.
Products containing DMAA were not banned in the UK at the time.
Miss Squires had run the London Marathon two years before and wanted to beat four hours for the race.
She had also completed the Great North Run and the Belfast Marathon.
Mr van Herrewege 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 [a] wall I will take it'."
DMAA has been banned by the US Army following the deaths of soldiers who had taken it.
The hearing was told Jack3D is still being sold on Amazon but DMAA has been removed as an ingredient.
Outside court, Mr van Herrewege called for better supervision of the "so-called health food and supplement industry".
He said her death had left a "gaping hole in their hearts and lives".
"The outcome of the inquest left us feeling a little numb. Claire took part in the marathon to do some good and challenge herself in the same way she did for many other events.
"Claire was passionately against the use of drugs and would never, ever, have taken anything that would have caused her harm, or even worse, risk her life."
Miss Squires chose to raise money for the Samaritans partly because her mother had volunteered for the charity for 24 years.
Her death led to a public outpouring of support for the organisation.
It has worked with her mother Cilla Squires to develop The Claire Squires Fund - a programme of projects to reflect how she would have wanted the money to be used.