What the study found
People who consumed the largest amounts of low- and no-calorie sweeteners experienced significantly faster declines in memory and thinking skills than those who consumed the least, according to a study published in Neurology, the medical journal of the American Academy of Neurology.
After adjusting for factors including age, sex, high blood pressure and cardiovascular disease, participants in the highest-consumption group showed a 62% faster decline in overall cognitive performance than the lowest group. Researchers said that gap was equivalent to about 1.6 additional years of cognitive aging over the study period.
Moderate intake was also linked to differences. The middle group declined 35% faster than the lowest group, roughly equal to 1.3 extra years of cognitive aging. The researchers noted that these figures describe changes in test performance, not a direct measure of biological brain aging, and do not mean everyone who uses artificial sweeteners will develop memory problems.
How the research was done
The team analyzed data from 12,772 adults in Brazil, who averaged 52 years old at the start and were followed for about eight years. At the outset, participants completed detailed questionnaires about what they had eaten and drunk during the previous year. Researchers used those answers to estimate daily intake of seven sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose.
Participants were divided into three groups by consumption. The lowest group averaged 20 milligrams per day and the highest averaged 191 milligrams per day, which the researchers said is roughly the amount of aspartame in one can of diet soda. Sorbitol, a sugar alcohol, had the highest average intake among the seven, at 64 milligrams per day.
Cognitive testing took place at the beginning, middle and end of the study. The assessments covered verbal fluency, working memory, word recall and processing speed.
Differences by age, condition and sweetener
The association was not uniform. Among adults younger than 60, higher sweetener consumption was tied to faster declines in verbal fluency and overall cognitive performance, but researchers did not see a similar pattern in those older than 60. The link was also stronger among people with diabetes than among those without the condition.
Six of the seven sweeteners were associated with faster declines in overall cognition, particularly memory: aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol. Tagatose showed no such association. The researchers cautioned that this does not establish that tagatose protects the brain or is safer than the others.
Limits and next steps
Study author Claudia Kimie Suemoto, MD, PhD, of the University of São Paulo 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." She noted that people with diabetes are more likely to use artificial sweeteners as sugar substitutes.
The researchers acknowledged several limitations. The analysis did not cover every sweetener on the market, and diet information came from participants' own recollections, which may be inaccurate. Because the study was observational, other factors could explain the relationship despite adjustments.
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." The work was supported by the Brazilian Ministry of Health, the Ministry of Science, Technology, and Innovation, and the National Council for Scientific and Technological Development.
