A mother who drank excessive amounts of Coca-Cola every day for years died after suffering a heart attack, likely brought on by her soft-drink addiction, a coroner has concluded, according to media reports in the country.

Natasha Harris, a 30-year-old stay-at-home mother of eight from Invercargill who reportedly drank 10 litres of Coca-Cola a day, died in February 2010.

The coroner's report was released on Tuesday and reported by New Zealand Television (TVNZ).

"I find that, when all the available evidence is considered, were it not for the consumption of very large quantities of Coke by Natasha Harris, it is unlikely that she would have died when she died and how she died," coroner David Crerar said in his report.

"Natasha Harris died of cardiac arrhythmia. On the balance of probabilities it is more likely than not that the drinking of very large quantities of Coke was a substantial factor that contributed to the development of metabolic imbalances, which gave rise to the arrhythmia."

He added that Coca-Cola could not be held responsible "for the health of consumers who drink unhealthy quantities of the product."

Woman had severe tooth decay

The coroner was also critical of Harris for not recognizing the risks associated with her diet.

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Natasha Harris, 30, a stay-at-home mother of eight from Invercargill, died of a heart attack in February 2010. Experts say the New Zealand woman's two-gallon-a-day Coca-Cola habit probably contributed to her death, a conclusion that led the soft-drink giant to note that even water can be deadly in excessive amounts. (New Zealand Herald/Associated Press)

"Natasha Harris knew, or ought to have known and recognised, the health hazard of her chosen diet and lifestyle," he said in his report.

"The fact she had her teeth extracted several years before her death because of what her family believed was Coke induced tooth decay, and the fact that one or more of her children were born without enamel on their teeth, should have been treated by her, and by her family, as a warning."

Karen Thompson, a spokeswoman for Coca-Cola Oceania, said in a statement last April that its products are safe.

"We concur with the information shared by the coroner's office that the grossly excessive ingestion of any food product, including water, over a short period of time with the inadequate consumption of essential nutrients, and the failure to seek appropriate medical intervention when needed, can be dramatically symptomatic."

One litre of Coca-Cola contains 97 milligrams of caffeine and 108 grams of sugar.

The World Health Organization recommends a daily maximum of 10 per cent of calories from free sugars. Generally, in Canada, healthy adults are advised to drink no more than 400 mg of caffeine daily, or roughly three cups of coffee, according to Health Canada.