Regularly consuming fizzy drinks laced with artificial sweeteners could raise the risk of heart and brain damage, concerning research suggests.
Aspartame – found Diet Coke, Pepsi Max and Sprite, as well as products like Extra chewing gum – has long been linked to health concerns including cancer, high blood pressure and stroke.
Now, Spanish researchers say consuming high levels of the additive may also age the brain and stiffen the heart.
In a study on mice, higher aspartame intake – roughly equivalent to three servings every fortnight – was linked to around a 20 per cent increased risk of mild cardiac hypertrophy, a condition in which the heart muscle becomes thickened, as well as accelerated cognitive decline.
The researchers also found that body fat dropped by around a fifth in the animals.
Writing in the journal Biomedicine and Pharmacotherapy, the researchers at the Centre for Cooperative Research in Biomaterials in San Sebastián, urged officials to review current aspartame consumption guidelines.
They said: ‘Aspartame does indeed reduce fat deposits by 20 per cent in mice, but it does so at the cost of mild cardiac hypertrophy and decreased cognitive performance.
‘Although this sweetener may help achieve weight loss in mice, it is accompanied by pathophysiological changes in the heart and, possibly, in the brain.
Commonly-used sweeteners including aspartame, found in drinks like Diet Coke, Sprite and products like Extra chewing gum as sugar alternatives, have long been linked to certain cancers, high blood pressure and strokes
‘These findings suggest aspartame at permitted doses can compromise the function of major organs, and so it would be advisable to reassess the safety limits for humans.’
In the study, mice were given a dose of 7mg of aspartame per kilogram of body weight. This was administered over three consecutive days every two weeks.
By comparison, the World Health Organization, the European Medicines Agency and the US Food and Drug Administration advise that people should consume no more than 50mg per kilogram of body weight per day.
Over a year-long follow-up, mice exposed to aspartame showed a reduction in heart output in both ventricles – falling by 26 per cent in the left ventricle and 20 per cent in the right.
The researchers also found septal curvature – the thick muscular wall separating the heart’s right and left ventricles – was reduced by 25 per cent.
The mice showed ‘signs of altered neurobehavior’ and ‘possible pathophysiological changes in the brain’, the study said.
However, the scientists acknowledged several limitations, including the length of the study, and said longer-term research would be needed.
The International Sweeteners Association (ISA) urged caution in interpreting the findings, arguing they could not be directly applied to humans.
Laurent Oger, Director General at the ISA, told the Daily Mail: ‘Key physiological differences between humans and mice, such as metabolism, lifespan, cardiac physiology, and brain energy utilisation, limit the relevance of the study’s conclusions.
‘Notably, the reduction in body weight and fat mass observed in mice contrasts with evidence from human clinical trials, which shows that aspartame and other low or no calorie sweeteners do not affect body weight on their own.
‘But may support weight management primarily by reducing sugar and, in turn, overall energy intake.
‘The reported cardiac and neurobehavioral alterations also occurred in aged mice, making it difficult to separate potential aspartame-related effects from normal aging.
‘Aspartame has been the subject of an overwhelming number of scientific studies and has been thoroughly researched and approved as safe by global food safety authorities.’
Concerns have also been raised previously about links between artificial sweeteners and cancer.
These fears intensified in 2023 after the World Health Organization classified aspartame as ‘possibly carcinogenic to humans’.
However, the UN agency said the risk applied only to very high levels of consumption, adding that an 11-stone (70kg) adult could safely drink around 14 cans of diet fizzy drinks a day.