Ian Harley, who worked for Southampton City Council as a gardener, was found dead in his flat last year

Colleagues told the hearing how Ian Harley would drink litres of the energy drink as he worked on the Southampton City Council open spaces team.

His family even wrote to the coroner saying they feared he may have died from the effects of consuming too much Red Bull.

However a toxicology test after his death could find no link between the drink and his death.

The inquest at Winchester heard how Mr Harley, 53, was found dead at his Southampton home on September 4 last year.

He had been signed off work for health reasons and was last seen alive by his colleague Martin Wright, who drove past him as he came out of a newsagent near his home on August 15.

His body was found by police after Mr Wright raised the alarm after noticing a stench of “rotting flesh”, and flies from Mr Harley’s home in Vanguard Road, Midanbury, the inquest was told.

Describing the moment he last saw Mr Harley, Mr Wright described him as looking ill and like he had lost weight.

Mr Harley was described as drinking the energy drink like “it was going out of fashion” for the past three years before his death.

Mr Wright said: “When he was with us in the winter he would come to work in the morning and would down two cans of Red Bull and do the same at the lunch and tea break.”

When his family entered Mr Harley's flat following his death, they discovered at least 100 discarded Red Bull cans and found a box of anti depressants, which were unopened.

Speaking at the hearing, Mr Harley’s mother Janet Harley said he was very private and had not visited his family face to face since the previous February.

She added: "When we went into the flat we counted all the cans and we gave up when we reached 100."

The inquest heard Mr Harley suffered from eczema, asthma and had suffered from depression.

Dr Sanjay Jogai told the hearing he believed that the most plausible cause of death would be a heart attack, and said toxicology tests revealed no link to Red Bull.

The inquest heard how only 4.5mg of caffeine per kilogramme was found in his liver. The level for the average fatality is 240mg per kilogramme.

Dr Jogai said: "The caffeine in his liver was far lower than what is associated with deaths."

He added therapeutic levels of pain killers, an anti depressant and alcohol were also in his system.

Coroner Karen Harrold recorded an open conclusion.

After the hearing, Janet Harley paid tribute to her son who she described as someone who loved Scouting and would be greatly missed.

What are the health effects of drinking too many energy drinks?

• Energy drinks have added sugars like glucose and sucrose which cause tooth decay.
• They also contain caffeine which can be addictive. It can also interact with heart medications and could cause heart arrhymthmia.
• The drink also increase the risk of osteoporosis as caffeine consumption causes the body to lose calcium which results weak bones.
• A regular can of Red Bull (250ml) contains 80mg of caffeine. Guidelines set the maximum amount of caffeine a person should consume each day at 400mg.