People who consume the highest amounts of low- and no-calorie sweeteners experience significantly faster declines in memory and thinking abilities than those who consume the least, according to a study published in Neurology, the journal of the American Academy of Neurology. The association was strongest among adults under 60 and those with diabetes.
Study author Claudia Kimie Suemoto of the University of São Paulo in Brazil and other researchers analysed data from 12,772 Brazilian adults with an average age of 52 who were followed for approximately eight years. Participants completed dietary questionnaires at the start and underwent cognitive assessments measuring memory, language, verbal fluency, working memory, word recall and processing speed at three points during the study.
Researchers estimated each person's daily intake of seven common sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. Those in the highest consumption group averaged 191 milligrams per day, roughly the amount of aspartame in one can of diet soda, while the lowest group averaged 20 mg/day.
After accounting for age, sex, high blood pressure and cardiovascular disease, participants in the highest consumption group showed a 62 percent faster decline in overall cognitive performance compared with the lowest group, equivalent to about 1.6 additional years of cognitive aging. Even moderate consumption was linked to measurable differences: the middle group experienced a 35 percent faster decline, equivalent to roughly 1.3 additional years of cognitive aging. These estimates describe changes in cognitive test performance rather than a direct measurement of biological brain aging.
"Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar; however, our findings suggest certain sweeteners may have negative effects on brain health over time," Suemoto said.
The association was not consistent across all age groups. Among adults younger than 60, higher sweetener intake was linked to faster declines in verbal fluency and overall cognitive performance, but researchers found no similar association among participants older than 60. The relationship was also stronger in people with diabetes than in those without.
Six of the seven sweeteners examined -- aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol -- were associated with faster declines in overall cognitive performance, particularly memory. Tagatose was the exception; researchers found no association between its consumption and cognitive decline in this study, though this finding does not establish tagatose as protective or safer than other sweeteners.
The findings represent an association rather than a proven cause-and-effect relationship, and researchers cannot conclude that consuming these sweeteners directly damages the brain or causes memory loss. Dietary information relied on participants' own recollections, and the analysis did not cover every artificial sweetener on the market.
"More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, may be effective alternatives," Suemoto said.
The research was supported by the Brazilian Ministry of Health, the Ministry of Science, Technology and Innovation, and the National Council for Scientific and Technological Development.
Analysis
Why This Matters
- The study challenges the assumption that replacing sugar with low- and no-calorie sweeteners is universally beneficial, particularly for brain health
- With diabetes prevalence rising globally and many patients turning to these sweeteners to manage sugar intake, the stronger association found in people with diabetes warrants attention
- The findings suggest even moderate consumption may be linked to measurable cognitive differences over time
Background
Artificial and low-calorie sweeteners are widely used in diet sodas, flavoured waters, energy drinks, yoghurt and low-calorie desserts, as well as sold separately for home use. They have been marketed as healthier alternatives to sugar, particularly for weight control and diabetes management. The study is one of the largest long-term investigations into whether these substances are associated with cognitive decline in a general adult population. It examined seven sweeteners commonly found in ultra-processed foods and beverages.
What to Watch
- Whether further observational and mechanistic studies confirm a causal link between specific sweeteners and cognitive decline
- Whether regulatory bodies such as the FDA or European Food Safety Authority review consumption guidelines in light of the findings
- Whether research into sugar alternatives such as applesauce, honey or maple syrup finds they carry different long-term cognitive effects
Checked
12 claims in this story checked against 1 source: 12 supported.
Show each claim
- SupportedSix sweeteners were linked to faster cognitive decline.Latest Science News -- ScienceDaily: “Six of the seven substances were associated with faster declines in overall cognitive performance, particularly memory. Those six were aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol.”
- SupportedThe research tracked 12,772 Brazilian adults for approximately eight years.Latest Science News -- ScienceDaily: “Researchers analyzed data from 12,772 adults across Brazil. Participants were 52 years old on average when the study began and were followed for approximately eight years.”
- SupportedThe highest-consumption group had a 62 percent faster decline in overall cognitive performance than the lowest-consumption group.Latest Science News -- ScienceDaily: “researchers found that participants in the highest consumption group experienced a 62% faster decline in overall thinking and memory abilities compared with those in the lowest group.”
- SupportedThe study was published in Neurology, the journal of the American Academy of Neurology.Latest Science News -- ScienceDaily: “A study published in Neurology , the medical journal of the American Academy of Neurology”
- SupportedClaudia Kimie Suemoto of the University of São Paulo in Brazil was a study author.Latest Science News -- ScienceDaily: “said study author Claudia Kimie Suemoto, MD, PhD, of the University of São Paulo in Brazil.”
- SupportedSuemoto said: “Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar; however, our findings suggest certain sweeteners may have negative effects on brain health over time,”Latest Science News -- ScienceDaily: “"Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar; however, our findings suggest certain sweeteners may have negative effects on brain health over time," said study author Claudia Kimie Suemoto, MD, PhD”
- SupportedThe lowest-intake group averaged 20 mg/day and the highest averaged 191 mg/day, roughly the amount of aspartame in one can of diet soda.Latest Science News -- ScienceDaily: “Those in the lowest consumption group averaged 20 milligrams per day (mg/day), while those in the highest group averaged 191 mg/day. For comparison, 191 milligrams of aspartame is roughly the amount found in one can of diet soda.”
- SupportedThe middle consumption group had a 35 percent faster decline than the lowest group, equivalent to roughly 1.3 additional years of cognitive aging.Latest Science News -- ScienceDaily: “Participants in the middle group experienced a 35% faster decline than those consuming the least, equivalent to roughly 1.3 additional years of cognitive aging.”
- SupportedAmong adults younger than 60, higher sweetener consumption was linked to faster declines in verbal fluency and overall cognitive performance; no similar association was found among participants older than 60.Latest Science News -- ScienceDaily: “Among adults younger than 60, higher sweetener consumption was linked to faster declines in verbal fluency and overall cognitive performance. However, researchers did not find a similar association among participants older than 60.”
- SupportedThe relationship was stronger in people with diabetes than in those without diabetes.Latest Science News -- ScienceDaily: “The relationship was also stronger in people with diabetes than in those without the condition.”
- SupportedSix sweeteners were associated with faster declines in overall cognitive performance, while tagatose was not associated with cognitive decline in this study.Latest Science News -- ScienceDaily: “Six of the seven substances were associated with faster declines in overall cognitive performance, particularly memory. Those six were aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol. Tagatose was the exception. Researchers found no association between its consumption and cognitive decline in this study.”
- SupportedSuemoto said: “More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, may be effective alternatives.”Latest Science News -- ScienceDaily: “"More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, may be effective alternatives."”