Lomu had suffered from kidney disease for two decades and had a transplant in 2004 but former All Blacks doctor John Mayhew said his death was unexpected.
“I can confirm that Jonah Lomu died this morning, most probably about eight or nine this morning” Mayhew told TV3.
“The family are obviously devastated, as are friends and acquaintances.
“It was totally unexpected. Jonah and his family arrived back from the United Kingdom last night and he suddenly died this morning.”
Lomu, who was awaiting another transplant and undergoing dialysis treatment, had undertaken commercial obligations at the recent Rugby World Cup in England.
His death took the rugby-mad country by surprise with an outpouring of messages of condolence from New Zealand and around the world flooding social media.
Lomu’s record of 37 tries in 63 tests was an impressive haul, all the more so considering he played much of his career and with nephritic syndrome, the disease that attacked his kidneys.
New Zealand Rugby, who arguably owe part of their huge commercial success over the last 20 years to Lomu’s performances at the 1995 World Cup, said they were “shocked and saddened” by Lomu’s death.
Born to Tongan parents in South Auckland, Lomu spent some of his childhood back in the Pacific Island nation after a cousin was killed with a machete in a street attack.
He was then sent to Wesley College where he quickly found his niche on the sports field and was timed running under 11 seconds in the 100 metres
The ravages of Lomu’s disease had begun to affect him and his performances went downhill from 1998, although he still made the 1999 World Cup squad and scored eight tries. He played his last test against Wales in 2002.
Lomu’s health deteriorated from that point and had a transplant in 2004 when a friend donated one of his own kidneys for the procedure.
By the time of the 2011 Rugby World Cup in New Zealand, when Lomu featured heavily in the opening ceremony, the kidney had begun to fail and he was forced back onto dialysis.