Wellington (AFP) - Jonah Lomu's former doctor on Tuesday dismissed speculation from an ex-teammate linking the rugby legend's shock death last year to the dietary supplement creatine.
Ex-All Black Joeli Vidiri told Britain's Daily Telegraph that he and Lomu took creatine while they were playing Super Rugby with the Auckland Blues in the 1990s.
Both developed the rare kidney disease nephrotic syndrome and Vidiri said "it does make you wonder" about use of the substance.
Creatine is a legal amino acid supplement marketed as boosting muscle mass and energy.
The University of Maryland Medical Center says that in high doses it has the potential for serious side effects, including kidney disease.
However, former All Blacks medic John Mayhew said Lomu's renal problems had been diagnosed during the period Vidiri was referring to and there was no evidence the player took creatine.
"Jonah was under pretty strict instructions from myself and from his renal specialists not to take this," Mayhew told TVNZ.
"At the time, we went through the drugs that Jonah couldn't take, that people with renal conditions had to avoid."
Mayhew, a close family friend who announced the star's death to the world last November, said the kidney condition cut short Lomu's career probably began before he ever picked up a rugby ball.
"We believe that Jonah's renal condition came from his childhood and pre-dated his rugby involvement," he said.
Lomu died unexpectedly at his Auckland home in November after returning from seeing his beloved All Blacks win the World Cup.
Mayhew said at the time the 40-year-old probably died from a blood clot that formed in his lungs during a long-haul flight, a scenario the kidney disease would have made more likely.
The death of a player seen as rugby's first global superstar prompted tributes from not only within the game but also Hollywood celebrities, charities and Britain's Queen Elizabeth II.