People who regularly have two or more diet soft drinks a day are more likely to die from heart disease, according to the University of Iowa Hospitals and Clinics study.

The study of 60,000 participants showed people who regularly consume diet soft drinks were 30 per cent more likely to suffer from a “cardiovascular event”.

While there are too many unknowns in this study such as diet, exercise habits and participant weight, according to dietician Catherine Forbes, she said it is a timely reminder that diet soft drinks are not a healthy alternative.

“A lot of diet soft drinks are high in caffeine which is not good,” she said.

In recent years Mrs Forbes said there has been a boom in sales for diet soft drinks in Australia.

“People are becoming more aware of the sugar content in regular soft drinks,” she said.

Mrs Forbes said similar studies have linked artificial sweeteners with disease, and showed people who drink diet soft drinks are less likely to eat healthy food.

“Soft drinks need to be treated like everything else – in moderation is fine,” she said. “To me it’s an extra food ... you’re better off having a glass of water. One or two a week would be fine.”