Artificial sweeteners, widely used as sugar substitutes, may accelerate brain aging and negatively impact cognitive functions, according to research from Brazilian scientists at the University of São Paulo, published in the prestigious journal Neurology.
In an eight-year study involving over 12,000 people aged 35 to 75, it was observed that individuals consuming the highest amounts of sweeteners exhibited significantly faster declines in mental performance. Consumers of these substances faced a 62% higher risk of global cognitive decline compared to those consuming the least. Moreover, they experienced more than twice the rate of decline in verbal fluency—the ability to quickly generate words—and showed noticeably poorer memory test results.
The researchers analyzed the impact of several popular substances, including aspartame, saccharin, acesulfame-K, erythritol, sorbitol, and xylitol. Only tagatose showed no association with cognitive decline. Notably, the study did not include sucralose, one of the most commonly used sweeteners today, although prior research has also indicated its potential negative effects on memory and executive functions.
According to the study’s lead author, Professor Claudia Kimie Suemoto, regular use of artificial sweeteners may accelerate the natural aging processes of the brain. The mechanisms behind this phenomenon are not yet fully understood. Scientists suggest potential roles for neurotoxic metabolites (such as those produced by aspartame), neuroinflammatory reactions within the nervous system, as well as disruptions to the gut microbiota, which can weaken the blood-brain barrier and indirectly affect brain function.
This research is observational, meaning it does not definitively prove causation. Data on sweetener consumption were collected via dietary questionnaires, which inherently carry some margin of error. The scientists also noted that accompanying factors play a significant role—for example, people with diabetes more often use sweeteners, and diabetes itself is an independent risk factor for cognitive decline.
Nevertheless, this study is among the largest and most comprehensive of its kind. Its findings add to the growing body of evidence questioning the safety of long-term sweetener use. Earlier studies have suggested possible links between sweeteners and cardiovascular diseases, metabolic disorders, and even cancer risk.
The World Health Organization (WHO), in a directive published in 2023, does not recommend sweeteners for weight control or chronic disease prevention, except in people with diabetes, where their use may be justified.
Researchers emphasize the importance of diet in middle age, when nutritional habits can shape brain health in later decades. The healthiest alternatives to sugar and sweeteners remain diets based on unprocessed foods rich in vegetables, fruits, whole grains, and healthy fats—as exemplified by Mediterranean and DASH diet models.
