In a Brazil-wide cohort study published in Neurology, researchers followed 12,772 adults (average age 52) for about eight years and found that those consuming the largest amounts of seven low- and no-calorie sweeteners experienced faster declines in memory and thinking—an effect the authors equate to roughly 1.6 years of extra brain aging, with the strongest associations in people under 60 and in participants with diabetes.
Key Takeaways
- The study tracked 12,772 Brazilian adults over an average of eight years to measure cognitive change.
- Seven sweeteners were examined: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose.
- Participants in the highest consumption group averaged 191 mg/day; the lowest group averaged 20 mg/day.
- Highest consumers showed a 62% faster decline in overall cognition versus lowest consumers (about 1.6 years of brain aging).
- The association was stronger for adults younger than 60 and for people with diabetes; no clear link was seen in those over 60.
- Tagatose was not associated with cognitive decline in this analysis.
- The study found associations but did not establish that sweeteners cause cognitive decline.
Verified Facts
The research cohort included 12,772 adults from across Brazil with a mean age of 52. Dietary intake was assessed at baseline with questionnaires covering the prior year; participants were grouped into thirds based on total intake of the seven sweeteners. The lowest tercile averaged about 20 mg/day and the highest tercile about 191 mg/day. For aspartame specifically, the authors note that the higher average intake corresponds roughly to the amount in one can of diet soda.
Cognitive performance was measured at three time points (baseline, mid-study and end) using tests of verbal fluency, working memory, word recall and processing speed. After adjusting for age, sex, hypertension and cardiovascular disease, the highest consumers showed a 62% faster decline in overall thinking and memory compared with the lowest consumers; the middle group declined 35% faster than the lowest.
When results were stratified by age, associations were observed primarily among participants under 60 years old, where declines in verbal fluency and global cognition were most apparent. No statistically significant associations were reported for participants older than 60. The pattern was more pronounced among people with diabetes than among those without diabetes.
Examining individual sweeteners, intake of aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol were each linked to faster cognitive decline in pooled analyses; tagatose showed no association. The study authors acknowledge limitations, including reliance on self-reported diet and the fact that not every artificial sweetener on the market was included.
Context & Impact
Low- and no-calorie sweeteners are common in ultra-processed foods such as diet sodas, flavored waters, sugar-free yogurts and low-calorie desserts; some are also sold as tabletop sweeteners. Public health interest has grown because these substitutes are widely consumed, especially by people trying to control weight or blood glucose.
If the observed associations reflect a causal effect, even modest cognitive changes at the population level could have meaningful public health implications because of the high prevalence of sweetener use. However, observational data cannot prove causation, and individual risk may depend on dose, metabolic health and other lifestyle factors.
Clinicians and consumers should weigh these findings alongside evidence on metabolic outcomes, cardiovascular risk and calorie reduction. For people with diabetes—who in this study showed stronger associations—the findings may prompt closer review of sweetener use, but clinical guidance should await replication and intervention trials.
Official Statements
“Low- and no-calorie sweeteners are often seen as healthier alternatives to sugar, but our results suggest some may be linked to worse cognitive outcomes over time,”
Claudia Kimie Suemoto, MD, PhD, University of São Paulo
Explainer
Unconfirmed
- Whether the observed associations reflect a direct causal effect of sweeteners on brain health rather than unmeasured confounding.
- Potential differences in risk tied to sweetener sources (e.g., beverages versus processed foods) were not fully resolved.
- Long-term effects of sweetener substitutions such as fruit purées, honey or other natural sweeteners remain untested in this cohort.
Bottom Line
This large observational study links higher consumption of several artificial sweeteners to faster declines in memory and thinking, equivalent to roughly 1.6 years of additional brain aging in the highest intake group. The findings—stronger in adults under 60 and in people with diabetes—call for replication, mechanistic studies and randomized trials before clinical or public-health recommendations change.