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A large, new analysis published in Neurology this month links higher intake of several low- and no‑calorie sweeteners with a faster decline in memory and thinking skills—especially in people under 60 and those with diabetes. While the research does not establish cause and effect, it raises timely questions about the long‑term brain effects of widely used sugar substitutes.
What the researchers did and found
Researchers followed 12,772 adults in Brazil for roughly eight years, periodically testing memory, verbal fluency and processing speed while tracking dietary intake. The team focused on seven common sweeteners and grouped participants by average daily consumption to compare cognitive trajectories over time.
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The study examined these sweeteners: aspartame, saccharin, Acesulfame K, erythritol, xylitol, sorbitol and tagatose. Participants in the highest intake group averaged about 191 mg per day; the lowest group averaged roughly 20 mg per day.
After adjusting for age, sex, blood pressure and cardiovascular disease, people with the highest intake showed a 62% faster rate of cognitive decline than those with the lowest intake—an effect the authors estimated as similar to about 1.6 extra years of brain aging. Those in the middle group declined about 35% faster than the lowest group.
Who appeared most affected
The association was strongest among adults younger than 60; it was not observed in the same way among participants over 60. The signal was also clearer in people with diabetes, a group that commonly uses sugar substitutes to limit carbohydrate intake.
When the team looked at individual compounds, six sweeteners were linked to faster overall cognitive decline—particularly memory—while tagatose showed no significant association in this analysis.
Quick takeaways
- Scope: Large cohort (12,772 people) followed for ~8 years; repeated cognitive testing.
- Magnitude: Highest consumers had a 62% faster decline versus lowest consumers (≈1.6 years of brain aging).
- Most affected: Adults under 60 and people with diabetes appeared to show stronger links.
- Not all sweeteners: Tagatose was the only compound in this set not associated with decline.
- Study type: Observational—association, not proof of causation.
What the results mean — and what they don’t
This is an observational study, so it cannot determine whether sweeteners directly damage cognition. Diet was self‑reported, which can introduce errors, and the analysis did not cover every sugar substitute on the market. Residual confounding—unmeasured differences between groups—could also influence the results.
Still, the pattern observed across several compounds and the size of the cohort make the findings notable. Lead investigator Claudia Kimie Suemoto of the University of São Paulo called for more research to replicate the results and to explore whether other sweetening approaches—whole‑food or minimally processed options—affect brain health differently.
Practical implications for readers
These findings do not demand immediate alarm, but they do suggest caution. For people who regularly consume diet sodas, tabletop sweeteners or sugar‑free packaged foods, it may be reasonable to reassess long‑term habits and to discuss concerns with a healthcare provider—particularly for those with diabetes or other risk factors for cognitive decline.
Researchers say follow‑up studies, including trials and investigations into biological mechanisms, are needed to clarify whether and how specific sweeteners might influence brain aging.
