A personal trainer and dad made a fatal error when he mixed a toxic amount of caffeine powder with water, an inquest heard.

Thomas Mansfield, aged 29, of Lawson Road, Colwyn Bay, who also worked as a security guard, had 392 milligrammes of caffeine per litre of blood – the equivalent of drinking between 98 and 196 typical cups of coffee.

The hearing at Ruthin was told he had bought the powder online and it had the legally required warnings.

Suppliers Blackburn Distributions, which sell the product for £23, warn: "Doses should not be taken in more than 200mg at any one serving and no more than 400mg per day.

"Caffeine powder is highly potent stimulant and requires a small dosage to provide strong effects.”

The company add: "We now provide scoops for measuring this product out for orders up to 2kg. DO NOT under any circumstances use teaspoon or other volume based measurements to dose this product. A single teaspoon of pure powdered caffeine is roughly equivalent to the amount in 28 cups of coffee.”

Coroner John Gittins said caffeine powder, if used properly, was regarded as a safe product, and sold legally. He was “massively reassured” that some action had been taken by providing a measuring scoop.

Mr Gittins told Mr Mansfield’s widow Suzannah that if Mr Mansfield had such a scoop, rather than using scales, “he probably would still have been with you.”

Mr Gittins said other people may avoid a mistake in the future because of the changes that have occurred.

He recorded a conclusion of misadventure.

The coroner said Mr Mansfield’s digital scales started weighing from 2gms and he took “far too high” a dose. He may have been aiming for the mid-range of the recommended dose but got his “maths wrong” and miscalculated, consuming around 5gms of the supplement.

Mr Gittins remarked to his family :”It doesn’t make it better in any way, perhaps it makes it even worse – this is an error.”

Mrs Mansfield said in a statement that her husband had his own business and was “really healthy.”

He died on January 5 last year after being rushed by ambulance to the emergency department at Glan Clwyd Hospital.

Mrs Mansfield said she had watched him weigh the powder and he then took a sip of the drink before he “necked” the remainder.

“Within seconds he said he didn’t feel well. He said his heart was going fast,” she recalled.

A short time later she heard a noise and went to her husband who was on a couch and had froth coming from his mouth.

Ben Blackburn, managing director of the caffeine powder distributor, said the recommended dose was 60-300 mgs twice a day. The product had the legally required warnings on packaging.

Pathologist Dr Mark Atkinson said the cause of death was “caffeine toxicity.”

Mr Mansfield’s family didn’t wish to make any comment after the inquest.

But they said previously: ”Tom was an amazing young man and an absolute inspiration to us all. His enthusiasm and dedication were second to none and he will be sadly missed.”