Some widely used sugar substitutes may be associated with a rapid decline in memory and thinking skills over time, according to a study published in . NeurologyMedical Journal of the American Academy of Neurology.
The study followed nearly 13,000 adults and looked at seven sweeteners that contained little or no calories. Those who had the highest total intake had a more rapid decline in cognitive performance than those who had the lowest intake. This association was particularly strong among patients with diabetes.
These results do not indicate that sweeteners directly cause cognitive decline. These reveal associations and mean that other factors may help explain the pattern.
Investigating 7 Common Sweeteners
Researchers studied aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol, and tagatose.
These ingredients are frequently added to ultra-processed products such as flavored waters, soft drinks, energy drinks, yogurt, and desserts that are marketed as low-calorie. Some are sold separately for use in coffee, tea, cooking, and baking.
“Low- or zero-calorie sweeteners are often considered healthy alternatives to sugar, but our findings suggest that certain sweeteners may have long-term negative effects on brain health,” said study author Claudia Kimie Suemoto, MD, PhD, of the University of São Paulo in Brazil.
Tracking brain health over 8 years
The study included 12,772 adults living across Brazil. Participants had an average age of 52 years and were monitored for approximately 8 years.
At the beginning of the study, participants completed a detailed food questionnaire describing what they ate and drank in the previous year. The researchers then divided them into three groups depending on their total sweetener intake.
Those in the lowest intake group had an average of 20 milligrams per day (mg/day), while those in the highest intake group had an average of 191 mg/day. In the case of aspartame, the highest group’s intake was about the same as the amount of aspartame in a can of diet soda.
Sorbitol was the most commonly consumed individual sweetener, with an average intake of 64 mg/day.
Participants completed cognitive assessments at the beginning, midpoint, and end of the study. The tests measured several aspects of brain function, including verbal fluency, working memory, word recall, and processing speed.
Verbal fluency refers to the ability to quickly retrieve and generate words. Working memory is the brain’s short-term system for retaining and using information, and processing speed reflects how quickly a person understands and responds to information.
Increased intake leads to accelerated cognitive decline
After taking into account age, gender, high blood pressure, cardiovascular disease, and other relevant factors, the researchers found clear differences between the intake groups.
Those who ate the most sweeteners experienced overall declines in thinking and memory 62% faster than those who ate the least. The researchers estimated that this difference was equivalent to about 1.6 years of additional aging.
Participants in the medium consumption group experienced a 35% faster decline than that observed in the lowest group. This difference corresponds to approximately 1.3 years of aging.
Strong association in adults under 60
Age seems to influence the results. Among participants under 60, those who consumed the most sweeteners had faster declines in verbal fluency and overall cognitive performance than those who consumed the least.
Researchers did not find a similar association among participants aged 60 and older.
The association between sweetener intake and accelerated cognitive decline was also stronger in people with diabetes than in people without diabetes. Diabetics are often advised to limit products that quickly raise blood sugar levels, so they may use sugar substitutes more often.
6 sweeteners linked to memory changes
When researchers looked at sweeteners individually, six were associated with a rapid decline in overall cognition, especially memory.
Those sweeteners were aspartame, saccharin, acesulfame K, erythritol, sorbitol, and xylitol.
Tagatose was the only sweetener in the study that was not associated with cognitive decline.
“We found an association with cognitive decline in middle-aged people with and without diabetes, but those with diabetes were more likely to use artificial sweeteners as a sugar substitute,” Suemoto said. “Further research is needed to confirm our findings and investigate whether other refined sugar substitutes such as applesauce, honey, maple syrup, and coconut sugar are effective alternatives.”
Important limitations of the study
This study did not include all artificial sweeteners currently used in food and beverages, so the results cannot be applied to all sugar substitutes.
Information regarding diet was also provided by the participants themselves. Self-reported dietary data can be incomplete because people can forget food or misjudge their intake.
Most importantly, this study was observational. It identified a link between increased intake of sweeteners and accelerated cognitive decline, but could not prove that sweeteners caused those changes.
Main findings
- The study followed 12,772 adults with an average age of 52 years.
- Researchers looked at seven types of sweeteners commonly found in flavored waters, sodas, energy drinks, yogurt, low-calorie desserts, and other ultra-processed foods.
- Participants who ate the highest total intake had faster overall thinking and memory decline than those who ate the lowest.
- This difference corresponds to approximately 1.6 additional years of ripening.
- This association was observed in adults younger than 60 years, but not in adults older than 60 years.
- Although the results of this study show an association, they do not prove that sugar substitutes cause cognitive decline.
This 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.
