Long-term aspartame may harm mouse brain and heart function, study warns

A new study suggests that long-term aspartame consumption, even at levels deemed safe, may disrupt brain and heart function in mice. Published in Biomedicine & Pharmacotherapy, the research raises concerns about the artificial sweetener's impact on energy processing and organ health.

The year-long study tracked mice given aspartame at doses below current safety thresholds. After two months, their brains showed increased glucose uptake, but by six months, this effect reversed into a decline. Over time, treated mice also developed higher brain lactate levels, which can impair energy production and weaken neuron performance.

Behavioural tests revealed further issues. Aspartame-exposed mice struggled with spatial learning and memory, taking longer to navigate a maze compared to untreated ones. The study also identified mild cardiac hypertrophy—a thickening of heart tissue—reducing pumping efficiency and oxygen delivery to organs.

These findings follow earlier warnings. In May 2023, the WHO advised against long-term use of sugar-free sweeteners like aspartame, linking them to higher risks of type 2 diabetes and heart disease. Two months later, the WHO and IARC classified aspartame as possibly carcinogenic, with concerns over liver cancer.

The researchers urge a review of current aspartame intake guidelines, stressing that chronic exposure—even at low doses—may pose risks to brain and heart function. Their work adds to growing calls for stricter scrutiny of artificial sweeteners in food and drink.