WELLINGTON, NEW ZEALAND—Experts say a New Zealand woman's 10-litre-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.

Natasha Harris, a 30-year-old, stay-at-home mother of eight from Invercargill, died of a heart attack in February 2010. Fairfax Media reported that a pathologist, Dr. Dan Mornin, testified at an inquest Thursday that she probably suffered from hypokalemia, or low potassium, which he thinks was caused by her excessive consumption of Coke and overall poor nutrition.

Symptoms of hypokalemia can include abnormal heart rhythms, according to the U.S. National Institutes of Health.

Mornin said that toxic levels of caffeine, a stimulant found in Coke, also may have contributed to her death, according to Fairfax.

Harris' partner, Chris Hodgkinson, testified that Harris drank between 8 and 10 litres (2.1 and 2.6 gallons) of regular Coke every day.

“The first thing she would do in the morning was to have a drink of Coke beside her bed and the last thing she would do at night was have a drink of Coke,” Hodgkinson said in a deposition. “She was addicted to Coke.”

Hodgkinson also said Harris ate little and smoked about 30 cigarettes a day. In the months before her death, he said, Harris experienced blood pressure problems and lacked energy.

He said that on the morning of her death, Harris helped get her children ready for school before slumping against a wall. He called emergency services and tried mouth-to-mouth resuscitation but couldn't revive her.

Another pathologist, Dr. Martin Sage, said in a deposition that “it is certainly well demonstrated that excessive long or short term cola ingestion can be dramatically symptomatic, and there are strong hypothetical grounds for this becoming fatal in individual cases.”

Inquests such as this are sometimes held for unusual or unexplained deaths in New Zealand, and can help shape future health policies. With the evidence in the case now complete, the coroner's office will compile and issue a final report into the death.

In an interview with The Associated Press, Lisa Te Morenga, a nutritionist at the University of Otago, said excessive consumption of any type of liquid in a cool climate would be likely to play havoc with the body's natural systems and balance.

Karen Thompson, a spokeswoman for Coca-Cola Oceania, said in a statement 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.”