A young man who had been taking health supplements he purchased online from an American company, died from suspected water toxicity, an inquest in Dublin heard.

The body of Luke McGuire, 26, was found in the back garden of his family home in in Ranelagh, South Dublin on June 2, 2011, the Irish Independent reports.

His father Brian McGuire told Dublin Coroner's Court on Wednesday that his son took his health very seriously and did not drink or take drugs.

The inquest heard the 26-year-old followed a strict diet of "very low protein" vegetarian diet of raw vegetables, fruit and baked potatoes in the months leading up to his death.

The diet was designed by Robert Young, a doctor and nutritionist based in California who practices alternative medicine.

McGuire told the court his son said he was “feeling weird” prior to his death.

"The next morning he said to me that he was taking these salts, and that he thought they were making him feel ill in some way and that he felt thirsty,"McGuire said.

The court heard that Luke had purchased salts -- labelled 'pHour Salts' and 'PuripHy' on the Internet through Young’s website. According to the website the salts "help you maintain the alkaline integrity of your cells, organs, and body" and the PuripHy helps your blood absorb more oxygen from the water you drink.

The deceased stopped taking the salts on the morning of his death but drank a lot of water throughout the day.

The young man appeared to be fine when he came into the kitchen while his family were having dinner. He then went back out to the garden and twenty minutes later his mother, Marie Rooney, found him lying on the ground. His father and a family friend administered CPR before he was taken to St James's Hospital, where he was pronounced dead.

Pathologist Dr Ciaran O’Riain said it was a possibility the salts could have been a contributing factor in the young man's death. He added that the most significant finding at the autopsy was tonsillar herniation due to swelling in the brain. He concluded the swelling was caused by hyponatraemia, that is caused by lower than normal sodium levels in the blood, which, he said, may be related to water intoxication.

Dr O’Riain adjourned the inquest until November 8.