A sweeping study of nearly 13,000 adults has found a striking link between consumption of popular sugar substitutes and accelerated decline in memory and thinking ability, raising fresh questions about whether these widely trusted ingredients truly deserve their health halo.
The research, published in Neurology, the journal of the American Academy of Neurology, tracked Brazilian participants over eight years and examined seven common artificial sweeteners: aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol, and tagatose. Those who consumed the highest total amounts showed cognitive decline 62 percent faster than those who consumed the least, a gap equivalent to roughly 1.6 additional years of aging.
The participants, averaging 52 years old at enrollment, filled out detailed dietary questionnaires at the start. Researchers then divided them into consumption tiers. The lowest group averaged 20 milligrams daily, while the highest averaged 191 milligrams, comparable to the aspartame in a single can of diet soda. Sorbitol dominated the individual sweetener totals, with participants consuming an average of 64 milligrams per day across the study population.
Cognitive assessments conducted at the beginning, middle, and end of the study measured verbal fluency, working memory, word recall, and processing speed. The pattern held even after researchers accounted for age, sex, high blood pressure, cardiovascular disease, and other confounding factors.
Age and diabetes status shaped the findings in interesting ways. Adults under 60 who consumed the most sweeteners experienced sharper declines in verbal fluency and overall cognition than older participants, though researchers found no such link among those 60 and above. The connection was considerably stronger among people with diabetes, who tend to use artificial sweeteners more heavily because they're often advised to avoid products that spike blood sugar rapidly.
Six of the seven sweeteners tested, all except tagatose, showed associations with faster cognitive decline, particularly affecting memory. The researchers stressed that their work identified correlation, not causation. Other factors could explain why heavy sweetener users experience steeper mental decline.
The study's scope has limits. It did not capture every artificial sweetener on the market, so its conclusions cannot stretch to cover all sugar substitutes universally. Participants reported their own diet, and self-reported dietary data can be imperfect as people forget foods or misjudge portions. Most critically, the observational design means the researchers could document a relationship but could not prove the sweeteners caused the cognitive changes.
Claudia Kimie Suemoto, the study's lead author from the University of São Paulo, called for more research to confirm the findings and to evaluate whether other refined sugar alternatives like applesauce, honey, or maple syrup might offer safer options. Her team's work was funded by the Brazilian Ministry of Health and related scientific agencies.
Author Jessica Williams: "These findings flip the script on a category we've long treated as the safer choice, and they should prompt consumers to think twice before reaching for that diet soda or sugar-free yogurt."
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