DIET fizzy drinks raise your risk of heart disease and stroke by 10 per cent, a study claims.
Less than a can a day could be enough to cause health damage.
Millions of Brits drink the sugar-free sweetened drinks because they have zero calories.
But scientists at the French National Institute for Health said it is wrong to think of artificial sweeteners as a totally safe swap for sugar.
“Artificial sweeteners are in thousands of food and beverage brands worldwide.
“However, they remain a controversial topic and are currently being re-evaluated by health agencies.”
The study said 77.6mg of sweetener per day was the average for a “high consumer” and 7.5mg per day was low.
An average diet fizzy drink contains 42mg per 100ml, it added – 140mg per can.
It means as little as half a can could be bad for you.
Data from 130,000 French people found a third of people regularly guzzle the sugar swaps, which include aspartame, sucralose and acesulfame potassium.
The top sweetener consumers had a heart disease rate of 346 per 100,000 – 10 per cent higher than 314 per 100,000 for the lowest.
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Their stroke rate was 195 compared to 150 – a 30 per cent rise.
Dr Touvier added: “These food additives, consumed daily by millions of people, should not be considered a healthy and safe alternative to sugar.”
NHS advice says sweeteners are safe and can help to keep blood sugars low for diabetics and reduce the risk of tooth decay.
Tracy Parker, of the British Heart Foundation, said more research on sweeteners is needed.
She said: “Approval before they can be added to food is a rigorous process, so you can feel confident they are safe to eat.
“While these findings shouldn’t cause undue concern, it’s always a good idea to look at the amount of sugar and sweeteners in your diet.”