Top 6 artificial sweeteners associated with accelerated brain aging

An eight-year study tracking brain health of 12,772 Brazilian adults has associated six sugar substitutes with faster declines in memory and thinking skills over time.

Ultra-processed products marketed as low in calories — including flavoured water, soft drinks, energy drinks, yogurt and desserts — frequently add sugar substitutes, known as sweeteners. Several are also sold separately for use in coffee, tea, cooking or baking. For the study, researchers nominated seven common sweeteners for investigation. These were aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol and tagatose.

Participants for the study were, on average, 52 years old and monitored for approximately eight years. Participants completed detailed food questionnaires at the beginning of the study, which described what they had eaten and drunk during the previous year. According to their total sweetener intake, participants were then placed into three groups.

The lowest consumption group averaged 20 mg/day while an average of 191 mg/day was the case for the highest consumption group. In the case of aspartame, the amount consumed by the highest group was roughly equal to the aspartame in one can of diet soda. Cognitive assessments were also completed by participants at the beginning, midpoint and end of the study.

Several aspects of brain function, including verbal fluency, working memory, word recall and processing speed, were measured by the tests. For the purpose of the study, verbal fluency referred to the ability to quickly retrieve and produce words; working memory to the brain’s short-term system for holding and using information; and processing speed to how quickly a person can understand and respond to information.

Researchers found — after accounting for age, sex, high blood pressure, cardiovascular disease and other relevant factors — that there was a clear difference between the intake groups. People who consumed the greatest amounts of sweeteners experienced a 62% faster decline in overall thinking and memory abilities compared with those who consumed the least. The researchers estimate that this difference was comparable to about 1.6 additional years of aging.

Regarding participants in the middle consumption group, that difference was comparable to approximately 1.3 years of aging — with a decline that was 35% faster than the decline observed in the lowest group. Notably, of the seven sweeteners studied, only one — tagatose — was not linked to cognitive decline. The remaining six were associated with faster declines in overall cognition, particularly memory.

“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, of the University of São Paulo in Brazil.

Other key findings of the study were that age appeared have an influence. For participants younger than 60, those who consumed the most sweeteners experienced faster declines in verbal fluency and overall cognitive performance than those who consumed the least — the same association was not found in among participants older than 60.

There was also stronger connection between sweetener intake and faster cognitive decline among people with diabetes compared with those without the condition. “While we found links to cognitive decline for middle-aged people both with and without diabetes, people with diabetes are more likely to use artificial sweeteners as sugar substitutes,” Suemoto 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.”

Limitations of the research include that not every artificial sweetener currently used in food and beverages was included — so the findings cannot be applied to all sugar substitutes. Also, self-reported diet data can be imperfect. Dietary information was provided by the participants themselves, and people may forget foods or misjudge how much they consumed.

Most importantly, the study was observational, identifying a relationship between higher sweetener consumption and faster cognitive decline, but it could not establish that the sweeteners caused those changes. The results do not show that sweeteners directly cause cognitive decline: they reveal an association, meaning other factors could help explain the pattern.

The study was published in Neurology (doi.org/10.1212/WNL.0000000000214023), the medical journal of the American Academy of Neurology.

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