A 2025 study published in Neurology followed 12,772 Brazilian adults with an average age of 52 over eight years. People consuming the highest amounts of artificial sweeteners showed cognitive decline that was 62% faster than people consuming the lowest amounts. That works out to roughly 1.6 extra years of brain aging.
The sweeteners tracked were aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose. These aren't obscure lab chemicals. They're in diet sodas, flavored water, energy drinks, yogurt, and basically anything labeled "low-calorie" or "sugar-free."
The highest consumption group averaged 191mg per day, which is about one can of diet soda worth of aspartame.
I used artificial sweeteners for years thinking I was being smart. Sugar-free this, zero-calorie that. It felt like a clean trade. The research suggests it wasn't…
The decline showed up most strongly in memory, verbal fluency, and overall thinking speed.
The effect was strongest in adults under 60 (no significant link appeared in people over 60) and in people with diabetes, who are also the population most likely to use sweeteners as a sugar substitute.
One sweetener, tagatose, showed no link to cognitive decline. Worth noting if you're looking at alternatives.
The researchers are clear: this is observational. They can't prove causation from this data alone. But 8 years and 12,000+ people showing 62% faster decline isn't something to brush off because the mechanism isn't confirmed yet.
You might ask what to actually drink instead. The boring answer is also the correct one: water, black coffee, green tea. Add honey if you want to make it sweet.
Thank you for reading! ❤️
—Ernest P.
Founder, Enhancing Brain
Health disclaimer: This newsletter is for educational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before making changes to your diet or supplementation.