We find it in light drinks, sugar-free chewing gum, diet yoghurts and even in some medicines. Over the years, aspartame has become the most widespread artificial sweetener, the choice of millions of people who want to reduce calories without giving up the sweet taste. But are we really sure that it is harmless?
In reality, scientific studies have long highlighted some side effects of aspartame and now new research by a Spanish team, published in Biomedicine & Pharmacotherapy, raises further doubts about the safety of aspartame, showing that even doses considered “safe” by health authorities could cause long-term damage to the brain and heart.
The study
Most previous research on aspartame had an important limitation: it tested very high doses for short periods, conditions far removed from the daily reality of consumers. To fill this gap, Spanish researchers conducted a year-long experiment, unfortunately on animals, using a very low dose of the sweetener.
The mice received the equivalent of 7 milligrams of aspartame per kilogram of body weight, about one-sixth of the maximum daily limit set by the World Health Organization, the European Medicines Agency and the FDA. A quantity that many regular consumers could easily consume in everyday life.
The results were surprising. Using PET scans, the researchers monitored glucose consumption in the brains of mice and discovered a worrying pattern.
After just two months, the brains of animals exposed to aspartame showed double the glucose consumption compared to controls, as if they were working under continuous strain. But this was only the beginning. As the months passed, instead of adapting, the brain entered a phase of “energy shutdown” and after ten months, glucose use had dropped to half that of untreated mice.
Chemical analyzes confirmed the picture, lactate levels in the brain had increased 2.5 times, a clear sign that brain cells were struggling to manage energy efficiently. This metabolic imbalance can translate into real problems: difficulty concentrating, weakened memory, lower mental resistance.
Behavioral tests then demonstrated this clearly. Mice treated with aspartame moved more slowly, explored less and took almost twice as long to complete learning and memory tasks. Some, after eight months, couldn’t even complete the tests.
But the brain wasn’t the only organ to show signs of stress. Other tests revealed mild thickening of the heart muscle, a condition that makes pumping less efficient. Each heartbeat carried less blood, reducing the oxygen supply to organs, including the brain itself.
As the study authors point out, this is the first research to demonstrate that aspartame can cause structural and functional changes in the heart. A fact that deserves serious attention.
The “sugar-free” paradox
There is a bitter irony in all this: Aspartame actually reduced fat deposits in mice by 20%, the goal for which it is chosen by millions of consumers. But at what price? A tired brain and a stressed heart seem like too high a cost to pay.
This study does not provide definitive answers for humans, but it asks fundamental questions that we cannot ignore. The observed effects occurred slowly, over months, which may explain why much previous research missed them.
Researchers are strongly calling for current safety limits to be re-examined and for long-term studies to be conducted in humans, monitoring brain metabolism, cardiac performance and cognitive function for years, not weeks.
How to protect ourselves
While we wait for science to provide further clarity, we can still make more informed choices:
The most important lesson of this study, however, is perhaps that low doses do not automatically mean low risk, especially when exposure is prolonged over time. Our body is a complex system, and the effects of what we eat every day can manifest themselves in subtle but significant ways.
The real question to ask is not just “is this safe?“, but “Do I really need it?“Perhaps the time has come to reconsider our relationship with sweets, whether artificial or not.
