Study links common sweeteners to faster cognitive decline
A Brazilian study found higher intake of several low-calorie sweeteners was associated with quicker declines in memory and thinking skills.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Adults who consumed larger amounts of several common low- and no-calorie sweeteners had faster declines in memory and thinking over time, according to research published in Neurology, the medical journal of the American Academy of Neurology. The study matters for people who use sugar substitutes as a routine alternative to sugar, especially adults with diabetes, but the researchers said the findings show an association rather than proof of harm.
The American Academy of Neurology said the research followed 12,772 adults in Brazil for about eight years. Participants were 52 years old on average when the study began.
Researchers examined seven sweeteners: aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol and tagatose. According to the American Academy of Neurology, those ingredients are used in products such as soft drinks, flavored water, energy drinks, yogurt and low-calorie desserts, and some are sold for home use in drinks, cooking or baking.
How the study measured intake and cognition
At the start of the study, participants filled out food questionnaires covering what they ate and drank during the previous year, according to the American Academy of Neurology. Researchers divided them into three groups based on total sweetener consumption.
The lowest-intake group averaged 20 milligrams a day, while the highest-intake group averaged 191 milligrams a day, the academy said. For aspartame, researchers said the highest group’s intake was about the amount found in one can of diet soda. Sorbitol had the highest average intake among the individual sweeteners, at 64 milligrams a day.
Participants took cognitive tests at the beginning, middle and end of the study, according to the American Academy of Neurology. The tests assessed several functions, including verbal fluency, working memory, word recall and processing speed.
Largest intake tied to steeper decline
After adjusting for factors including age, sex, high blood pressure and cardiovascular disease, researchers found that people in the highest-consumption group had a 62% faster decline in overall cognition than those in the lowest group, according to the American Academy of Neurology. The researchers estimated that gap as roughly equal to 1.6 extra years of cognitive aging.
The middle-consumption group showed a 35% faster decline than the lowest group, which researchers compared with about 1.3 years of aging, the academy said.
The link was stronger among people with diabetes, according to the American Academy of Neurology. The academy said people with diabetes may be more likely to use sugar substitutes because they are often advised to limit foods that quickly raise blood sugar.
Age also affected the results, according to the researchers. Among adults younger than 60, higher sweetener intake was associated with faster decline in overall cognition and verbal fluency. The American Academy of Neurology said the same association was not found among participants older than 60.
Researchers caution against causal claims
When researchers assessed the sweeteners separately, six were linked to faster declines in overall cognition, particularly memory, according to the American Academy of Neurology. Those were aspartame, saccharin, acesulfame K, erythritol, sorbitol and xylitol. Tagatose was the only sweetener studied that was not linked to cognitive decline.
Claudia Kimie Suemoto of the University of São Paulo, an author of the study, said low- and no-calorie sweeteners are often viewed as healthier substitutes for sugar, but the findings suggest some may have negative effects on brain health over time.
The researchers said the study has limits. It did not include every sweetener used in foods and beverages, and participants reported their own diets, which can introduce errors. The American Academy of Neurology also said the study was observational, meaning it cannot show that sweeteners caused the cognitive changes.
The research was supported by Brazil’s Ministry of Health, Ministry of Science, Technology, and Innovation, and National Council for Scientific and Technological Development, according to the American Academy of Neurology.
This story draws on original reporting from ScienceDaily.