Some sugar substitutes might have unexpected effects on long-term brain health, according to a study published in Neurology® on September 3, 2025.
Researchers found that people who consumed the most artificial sweeteners experienced faster declines in thinking and memory skills than those who consumed the least.
This effect was even stronger in people with diabetes. However, the study did not prove sweeteners caused this decline—only that there was a link.
The study looked at seven artificial sweeteners: Aspartame, Saccharin, Acesulfame-K, Erythritol, Xylitol, Sorbitol, Tagatose
These are found in many ultra-processed foods, including flavored drinks, yogurt, and low-calorie desserts.
Dr. Claudia Kimie Suemoto, a study author from the University of São Paulo in Brazil, said, “Low- and no-calorie sweeteners are often seen as healthy alternatives to sugar, but our findings suggest they might negatively affect brain health over time.”
The study involved 12,772 adults in Brazil, average age 52, who were followed for about 8 years. At the start, participants reported their food and drink intake. They were divided into three groups based on sweetener use: low (20 mg/day), medium, and high (191 mg/day). Sorbitol was consumed the most (64 mg/day).
Cognitive tests measured memory, language, and thinking skills at the start, middle, and end of the study.
Results showed that: High sweetener users had a 62% faster decline in thinking and memory (equivalent to 1.6 years of aging). Medium users had a 35% faster decline (1.3 years of aging). The effects were stronger in people under 60 and those with diabetes.
Six sweeteners—except tagatose—were linked to faster memory decline, especially in people with diabetes.
Dr. Suemoto noted that more research is needed to confirm the findings and to see if natural sweeteners like honey or maple syrup are safer.
Limitations: Not all sweeteners were studied, and participants self-reported their diets, which may not be accurate.
The study was supported by Brazilian government health and science agencies.
The study is published in Neurology.
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