Diet Soda Drinkers, Take Note: Sweeteners Tied to Faster Brain Aging
People who consume the most artificial and low-calorie sweeteners may be aging their brains significantly faster than people who consume the least, according to a large new study published in Neurology, the medical journal of the American Academy of Neurology.
What the study found
Researchers led by Dr. Claudia Kimie Suemoto at the University of São Paulo tracked 12,772 adults in Brazil, with an average age of 52, for roughly eight years. Participants reported their intake of seven common low- and no-calorie sweeteners: aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol, and tagatose.
The group with the highest sweetener intake, averaging around 191 milligrams a day (roughly what's in one diet soda, for aspartame specifically), showed cognitive decline 62% faster than the group with the lowest intake, which averaged about 20 milligrams a day. Researchers estimated that gap as equivalent to about 1.6 additional years of brain aging. Even the middle consumption group showed a 35% faster decline than the lowest group, equivalent to roughly 1.3 extra years.
Six of the seven sweeteners studied were linked to faster memory decline. Tagatose, a less common sweetener derived from fruit, was the exception and showed no association with cognitive decline. Sorbitol had the highest average individual consumption among participants, at 64 milligrams a day.
The association was stronger in adults under 60 and stronger still among participants with diabetes, a group that often relies on artificial sweeteners as a sugar substitute.
"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," Suemoto said.
What the study doesn't show
This is an observational study, meaning it can show a statistical association but can't prove that sweeteners directly cause faster cognitive decline. Participants self-reported their diets, which is always an imperfect method, and the findings apply specifically to the seven sweeteners tested, not to every sweetener on the market. The researchers themselves frame this as evidence worth taking seriously, not as a final verdict.
Why it matters
Sweeteners are marketed and often prescribed by doctors as the "safe" option for people managing diabetes, weight, or general sugar intake. This study doesn't overturn that guidance, but it does add brain health to the list of things worth weighing when choosing a sweetener, alongside the gut-microbiome research on sweetener and medication interactions that's also drawn attention this year. If you rely on diet soda, sugar-free products, or artificial sweeteners daily, this is a reasonable prompt to mention it at your next checkup, particularly if you're managing diabetes or already have concerns about memory or cognitive health.
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