A study published in Neurology, the medical journal of the American Academy of Neurology, found that adults who consumed the highest amounts of low- and no-calorie sweeteners experienced faster declines in memory and thinking skills over approximately eight years. The association was especially strong among people with diabetes, but the observational research does not show that sweeteners directly cause brain damage or memory loss.
Study followed nearly 13,000 adults
Researchers analyzed data from 12,772 adults in Brazil who were 52 years old on average when the study began. Participants were followed for about eight years and completed cognitive assessments at the beginning, middle and end of the study.
At the start, each participant completed a detailed questionnaire about the foods and drinks they had consumed during the previous year. Researchers used the responses to estimate daily intake of seven sweeteners: aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol and tagatose.
These ingredients are commonly found in ultra-processed products, including diet sodas, flavored waters, energy drinks, yogurt and low-calorie desserts. Some are also sold separately for use in food and beverages.
Participants were divided into three groups according to their estimated sweetener consumption. The lowest-intake group consumed an average of 20 milligrams per day (mg/day), while the highest-intake group consumed an average of 191 mg/day. For comparison, 191 milligrams of aspartame is approximately the amount found in one can of diet soda.
Sorbitol had the highest average intake among the seven sweeteners, at 64 mg/day. Sorbitol is a sugar alcohol, a category of sweeteners that provides sweetness and is commonly used as a sugar substitute.
The cognitive tests measured verbal fluency, working memory, word recall and processing speed. These abilities are important for memory, language and the brain’s ability to process information.
Higher intake was linked to faster cognitive decline
After adjusting for factors that can affect cognitive health, including age, gender, high blood pressure and cardiovascular disease, the researchers found that people in the highest-intake group experienced a 62% faster decline in overall thinking and memory skills than those in the lowest-intake group.
The difference was equivalent to approximately 1.6 years of additional cognitive aging over the study period. Participants in the middle-intake group experienced a 35% faster decline than those in the lowest-intake group, corresponding to approximately 1.3 additional years of cognitive aging.
These figures describe changes in performance on cognitive tests, not direct measurements of biological brain aging. They also do not mean that everyone who consumes artificial sweeteners will develop memory problems.
“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.
Association was stronger in some groups
The relationship between sweetener intake and cognitive decline was not consistent across all age groups. Among adults younger than 60, higher intake was associated with faster declines in verbal fluency and overall cognitive performance. The researchers did not find a similar association among participants aged 60 and older.
The association was also stronger among people with diabetes than among those without diabetes. This result is notable because people with diabetes often use sugar substitutes to manage their sugar intake.
When the researchers examined the sweeteners individually, six of the seven were associated with faster declines in overall cognitive performance, particularly memory. They were aspartame, saccharin, acesulfame K, erythritol, sorbitol and xylitol.
Tagatose was the exception: its intake was not associated with cognitive decline in this study. However, that finding does not show that tagatose protects the brain or that it is necessarily safer than the other sweeteners.
Researchers say more study is needed
The findings raise questions about whether replacing sugar with lower-calorie alternatives consistently provides the health benefits consumers expect, particularly when brain health is considered.
“We found an association with cognitive decline in middle-aged people, regardless of whether they have diabetes or not, and those with diabetes are 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.”
The study did not include every artificial sweetener available on the market, so its results may not apply to all sugar substitutes. The dietary data also relied on participants’ recollections of what they had eaten and drunk. People may forget items, underestimate portion sizes or report their habits inaccurately.
Because the research was observational, the researchers could not establish that sweeteners caused the cognitive changes. Other factors not fully accounted for in the analysis may help explain the association between sweetener intake and cognitive decline.
Further research is needed to determine whether sweeteners themselves contribute to changes in brain function, why some groups appear to be more strongly affected and whether different sugar substitutes have different long-term effects.
The research was supported by Brazil’s Ministry of Health, the Ministry of Science, Technology and Innovation, and the National Council for Scientific and Technological Development.
Source: www.sciencedaily.com
