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A study of 12,772 adults in Brazil found that higher consumption of six of seven tested sweeteners was associated with faster decline on cognitive tests over about eight years. The observational findings do not show that the sweeteners caused brain damage, and the association varied by age and diabetes status.
A study published in Neurology found that adults who reported consuming the most low- and no-calorie sweeteners had faster declines in memory and thinking-test performance than those reporting the least, over roughly eight years. The observational study linked six of the seven sweeteners examined with faster cognitive decline, but it does not establish that the ingredients caused the changes.
Researchers analyzed dietary and cognitive assessment data from 12,772 adults in Brazil, who were 52 years old on average when the study began. Participants reported their food and drink intake for the previous year, allowing researchers to estimate daily consumption of aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. They were followed for approximately eight years.
Participants in the lowest-intake group averaged 20 milligrams per day of the sweeteners, compared with 191 milligrams per day in the highest group. The report says 191 milligrams is roughly the amount of aspartame in one can of diet soda; that comparison is an illustration, not a measure of the combined sweeteners in a particular drink. Sorbitol had the highest average intake among the ingredients, at 64 milligrams per day.
Cognitive tests, administered at the beginning, midpoint and end of follow-up, assessed memory, language, verbal fluency, working memory and processing speed. After accounting for factors including age, sex, high blood pressure and cardiovascular disease, the highest-intake group showed a 62% faster decline in overall cognitive performance than the lowest-intake group. The middle group showed a 35% faster decline. The researchers expressed these differences as approximately 1.6 and 1.3 additional years of cognitive aging, respectively; these are estimates based on test performance, not direct measurements of biological brain aging.
What the Cognitive Scores Show
The results matter because low- and no-calorie sweeteners are used in products such as diet sodas, flavored waters, energy drinks, yogurt and low-calorie desserts, and are often chosen as substitutes for sugar. The study raises a question about whether regular use of some alternatives could be associated with changes in cognitive performance over time. It does not, by itself, show that consumers will develop memory problems or that switching sweeteners would prevent decline.
The researchers reported stronger associations among participants with diabetes and adults younger than 60. For those under 60, higher intake was associated with faster decline in verbal fluency and overall cognitive performance; the report says a similar association was not found among participants over 60. These subgroup results do not establish why the patterns differed, and they should not be read as proof that diabetes or age changes the effects of sweeteners.
For consumers, the findings are a reason for further research rather than a basis for treating every sweetener as harmful. People with diabetes may use these products to manage sugar intake, and this study did not test whether replacing sweeteners with sugar would improve health. Dietary choices and diabetes management should be discussed with a qualified health professional.
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How Researchers Compared Intake
The seven substances included in the analysis were aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. Six—every one except tagatose—were individually associated with faster declines in overall cognitive performance, particularly memory. Researchers found no association between tagatose intake and cognitive decline in this study. That result does not show that tagatose protects the brain or is safer than the other substances.
The study relied on participants’ dietary questionnaires to estimate intake and followed cognitive test results over time. Researchers adjusted for several health and demographic factors, but an observational design cannot rule out all differences between people with higher and lower intake. The findings concern associations with test performance, not a diagnosis of dementia or a direct scan-based measure of brain aging.
“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.”
— Claudia Kimie Suemoto, MD, PhD, University of São Paulo, study author
What the Study Cannot Establish
The study cannot show that sweeteners directly caused cognitive decline. People who consume more of them may differ in other ways that affect health, and dietary intake was estimated from questionnaires rather than continuously measured. Although researchers adjusted for several factors, the possibility of remaining confounding cannot be excluded.
The report does not establish whether a particular dose changes risk, whether stopping or reducing intake would alter cognitive outcomes, or why the associations appeared stronger in some groups. It also does not show that the findings apply equally to people in other countries or dietary settings. The absence of an association for tagatose is not evidence of a protective effect.
Questions for Further Research
The findings point to a need for further studies to test whether the associations can be replicated and to better distinguish the effects of individual sweeteners from other features of diet and health. Research would also need to clarify how intake over time relates to cognitive changes and whether the patterns differ by age or diabetes status.
For now, the report provides no evidence that a specific dietary change will prevent cognitive decline. The key next step is independent confirmation and closer study of cause and effect; the supplied report does not identify a follow-up trial or a planned date for additional results.
Key Questions
Which sweeteners were associated with faster cognitive decline?
The study reported associations for aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol. It found no association for tagatose in this analysis, which does not prove tagatose is protective or safer.
Does the study prove these sweeteners cause brain aging?
No. It was an observational study that found links between estimated intake and changes in cognitive test scores. It cannot establish cause and effect or show that sweeteners directly damage the brain.
What did the 62% figure mean?
After adjustments for several factors, the highest-intake group had a 62% faster decline in overall cognitive test performance than the lowest-intake group during the study. Researchers estimated this difference as about 1.6 additional years of cognitive aging; it was not a direct biological measurement.
Were the findings the same for all participants?
No. The association was stronger among people with diabetes. Researchers also reported links among adults younger than 60, but not a similar association among those older than 60. These subgroup patterns do not explain why the differences occurred.
Should people stop using sugar substitutes?
The study does not establish that stopping sweeteners would improve cognitive health or that replacing them with sugar is beneficial. People considering changes, particularly those managing diabetes, should discuss their diet with a qualified health professional.
Source: sciencedaily.com
