The family of a woman who drank up to eight litres of Coca-Cola a day - partly blamed for her death - say the soft drink should carry warning signs.

Invercargill mother-of-eight Natasha Marie Harris died in 2010 and the coroner's inquest into her death, in Invercargill on Thursday, was told the main cause was cardiac arrhythmia.

However, the 30-year-old also had severe hypokalemia - lack of potassium in the blood - probably related to drinking so much Coke, the Otago Daily Times reported.

Her partner, Chris Hodgkinson, said she had a poor diet and would drink Coke first thing in the morning and last thing at night.

All her teeth had been removed because they were rotting, prompting a dentist to remark about drinking too much Coke.

Her family say Coke should carry warning signs and they are hoping to obtain compensation from Coca-Cola for the children, who are now in care.

"It's destroyed the whole family. There's eight little children aged under 12 and their dad had to sit down after school and tell them their mother was dead," Ms Harris' mother-in-law, Vivien Hodgkinson, said after the inquest.

A Coca-Cola Oceania representative told the inquest there was no basis for finding the consumption of Coke caused Ms Harris' death.

"We deeply sympathise with the tragic death of Ms Harris, but we are firmly of the view her death was not due to the purchasing of Coca-Cola."

Pathologist Dan Mornin said Ms Harris' death was probably caused by a combination of factors, including poor diet.

She was also a heavy smoker, with a 30-a-day habit.