A study published in Neurology has linked higher intake of several widely used sugar substitutes to faster declines in memory and thinking over about eight years, with the strongest association seen among people with diabetes. Claudia Kimie Suemoto, who led the research, said the findings suggest some low- and no-calorie sweeteners may have negative effects on brain health over time.
The study followed 12,772 adults living across Brazil, whose average age was 52 at the start. Participants filled out detailed food questionnaires about what they had eaten and drunk in the previous year, then completed cognitive tests at the beginning, midpoint and end of the study. Researchers examined aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol and tagatose, all common substitutes in low-calorie products.
The numbers are what give the finding its weight. People in the highest intake group averaged 191 milligrams per day, compared with 20 milligrams in the lowest group. The heaviest users experienced a 62% faster decline in overall thinking and memory abilities than those who consumed the least, a gap the researchers estimated was comparable to about 1.6 additional years of aging. Those in the middle group still declined 35% faster, equal to roughly 1.3 years of aging. Among participants younger than 60, the highest intake group also showed faster declines in verbal fluency and overall cognitive performance.
Sorbitol accounted for the largest share of intake, with an average of 64 milligrams a day, while the amount of aspartame in the highest group was roughly equal to the aspartame in one can of diet soda. That makes the finding more immediate than it first sounds: these were not exotic chemicals used in rare products, but sweeteners commonly added to flavored water, soft drinks, energy drinks, yogurt and desserts marketed as low in calories, and some are also sold separately for coffee, tea, cooking or baking.
Still, the study stops short of saying the sweeteners caused the decline. It found an association, not proof of a direct cause, and that distinction matters because the same people who use these products most often may also differ in other ways the study could not fully untangle. Even so, the pattern was strongest in people with diabetes, which gives the result added weight for a group that often turns to these products as sugar replacements.
For now, the study leaves a hard-edged message rather than a final verdict. Higher intake of these sweeteners tracked with faster cognitive decline, and the link was strongest where many readers might expect the products to be most useful. What remains unresolved is the mechanism, though researchers say it could help explain why the association appears over time rather than all at once.
