Some commonly used sugar substitutes may be associated with faster decline in memory and thinking skills over time, according to a study published in The New York Times Magazine. Neurologymedical journal of the American Academy of Neurology.
The study included nearly 13,000 adults and examined seven sweeteners that contain few or no calories. People who consumed the highest total amounts showed faster cognitive decline than those who consumed the lowest amounts. This association was especially strong among people with diabetes.
The results do not show that sweeteners directly cause cognitive decline. They reveal a connection, meaning other factors may help explain the pattern.
Seven common sweeteners studied
The researchers studied aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol and tagatose.
These ingredients are often added to ultra-processed foods, including flavored waters, soft drinks, energy drinks, yogurt and desserts, which are marketed as low-calorie. Some are also sold separately for use in coffee, tea, cooking or baking.
“Low- and no-calorie sweeteners are often viewed as healthy alternatives to sugar, but our findings suggest that some sweeteners may have negative effects on brain health over time,” said study author Claudia Kimi Suemoto, MD, PhD, of the University of São Paulo in Brazil.
Tracking brain health over eight years
The study involved 12,772 adults living throughout Brazil. On average, participants were 52 years old and were followed for approximately eight years.
At the start of the study, participants completed detailed food questionnaires, describing what they ate and drank during the previous year. The researchers then divided them into three groups based on their total sweetener consumption.
People in the lowest intake group consumed an average of 20 milligrams per day (mg/day), while people in the highest intake group consumed an average of 191 mg/day. In the case of aspartame, the amount consumed by the higher group was approximately equal to the amount of aspartame in one can of diet soda.
Sorbitol was consumed in the highest amount of any single sweetener, with an average daily intake of 64 mg/day.
Participants completed cognitive tests at the beginning, middle, 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 find and pronounce words. Working memory is the brain’s short-term system for storing and using information, and processing speed reflects how quickly a person can understand and respond to information.
Higher intake is associated with faster cognitive decline
After controlling for age, gender, high blood pressure, cardiovascular disease and other important factors, the researchers found a clear difference between the treatment groups.
People who consumed the most sweeteners had a 62% faster decline in overall thinking and memory abilities than those who consumed the least. The researchers calculated that this difference equates to about 1.6 additional years of aging.
Participants in the medium intake group experienced a decline that was 35% faster than the decline observed in the lowest intake group. This difference was comparable to approximately 1.3 years of aging.
Stronger association in adults under 60 years of age
Age appeared to influence the results. Among participants under 60 years of age, those who consumed the most sweeteners experienced faster declines in verbal fluency and general cognitive abilities than those who consumed the least.
The researchers didn’t find the same association among participants over 60 years of age.
The association between sweetener consumption and faster cognitive decline was also stronger among people with diabetes than among people without the disease. People with diabetes may be more likely to consume sugar substitutes because they are often advised to limit foods that quickly raise their blood sugar levels.
Six Sweeteners Linked to Memory Changes
When the researchers examined the sweeteners individually, six of them were associated with faster declines in overall cognitive function, especially memory.
These 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.
“Although we found an association with cognitive decline in middle-aged people with and without diabetes, people with diabetes were more likely to use artificial sweeteners as sugar substitutes,” Suemoto said. “More research is needed to confirm our findings and to determine whether other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, could be effective alternatives.”
Important limitations of the study
The study did not include all artificial sweeteners currently used in foods and drinks, so the findings may not apply to all sugar substitutes.
Dietary information was also provided by the participants themselves. Because people may forget or misjudge food intake, self-reported dietary data may be imperfect.
Most importantly, the study was observational in nature. They found an association between higher sweetener consumption and faster cognitive decline, but were unable to establish that sweeteners caused these changes.
Key Findings
- The study included 12,772 adults with an average age of 52 years.
- Researchers studied seven sweeteners commonly found in flavored water, soda, energy drinks, yogurt, low-calorie desserts and other ultra-processed foods.
- Participants who consumed the highest total amounts experienced faster declines in overall thinking and memory skills than those who consumed the lowest amounts.
- The difference was comparable to about 1.6 additional years of aging.
- The association appeared in adults younger than 60 years of age, but not in those older than 60 years of age.
- The results show an association, but do not prove that sugar substitutes cause cognitive decline.
The study was supported by the Brazilian Ministry of Health, the Ministry of Science, Technology and Innovation, and the National Council for Scientific and Technological Development.