Diet drinks and artificial sweeteners that many use to cut their sugar consumption could actually put them at risk of developing type 2 diabetes, research suggests.
Scientists found just two weeks of high intake of low-calorie sweeteners was enough to significantly alter the make-up of bacteria in the gut.
This changes the way the body absorbs and regulates blood sugar, the researchers said, which over time increases the risk of developing diabetes.
The findings are particularly concerning because many people are at risk of diabetes – such as those who are obese or already have high blood sugar – use diet drinks and sweeteners.
The researchers, led by Professor Richard Young of Adelaide Medical School in Australia, tracked 29 young healthy people for two weeks.
Half were given capsules of sweeteners containing sucralose and acesulfame-K, the equivalent of about four and half cans of diet drink a day.
The other half were given placebo capsules containing no sweeteners.
The researchers analysed the bacteria in the volunteers’ guts and found a significant alteration in those who had consumed the sweeteners, along with lower release of the hormone GLP-1, which helps to control blood glucose levels.
The authors, presenting their findings at the European Association for the Study of Diabetes conference in Berlin, said: ‘Two weeks of low-calorie sweetener supplementation was sufficient to disrupt gut bacteria and increase the abundance of those normally absent in healthy individuals.
The authors said their findings supported ‘the concept that such sweeteners worsen blood sugar control in healthy subjects.’
But British experts warned the results were not definitive – and artificial sweeteners are a better alternative to sugar.
Professor Naveed Sattar, of the University of Glasgow, said: ‘This study, whilst well done, is not the same as taking one or two diet drinks containing sweeteners per day, more often than not with food.
‘This evidence will in no way stop me taking a can a day of a diet drink – or recommending such drinks as alternatives to sugar-rich drinks for patients.’
Dr Katarina Kos, diabetes and obesity lecturer at the University of Exeter, said: ‘The best option … may remain water as a zero calorie drink.
Gavin Partington, director general at British Soft Drinks Association, said: ‘Low calorie sweeteners are safe and have been approved by all leading health authorities around the world for decades, as well Cancer Research UK and Diabetes UK.
‘These claims run contrary to the substantial body of global scientific research which shows how low calorie sweeteners can safely help people to reduce their calorie intake and manage their weight.’