Sao Paola, Brazil (Enmaeya News) — They’re in yogurt, diet sodas, chewing gum and even protein shakes. Marketed for decades as guilt-free alternatives to sugar, artificial sweeteners are consumed daily by billions worldwide. But a new study suggests the compounds may carry hidden risks for the brain.
A paper published in Neurology reports that common sugar substitutes may accelerate cognitive decline, including memory loss, slower processing speed and reduced verbal fluency. The risk was found in adults as young as their 40s.
The study tracked 12,772 Brazilian civil servants over an average of eight years as part of the Brazilian Longitudinal Study of Adult Health, or ELSA-Brasil. Participants, ages 35 to 74, filled out detailed dietary questionnaires and took cognitive tests every four years.
Researchers examined consumption of seven widely used sweeteners: aspartame, saccharin, acesulfame-K, erythritol, sorbitol, xylitol and tagatose.
The results were stark. Those in the highest third of sweetener intake showed a 62% faster decline in cognitive function compared with those in the lowest third, equal to an extra 1.6 years of brain aging.
Even moderate consumers saw a 35% faster decline, the equivalent of 1.3 years.
“The results are a wake-up call to reassess what we consider ‘safe’ in our daily diets,” said lead author Dr. Luciana Bertoldi.
The effect was most pronounced in people under 60, suggesting midlife may be a particularly vulnerable stage. The decline was also stronger among participants with type 2 diabetes, who already face elevated dementia risk.
Though observational, the findings align with other studies raising concerns about sweeteners’ impact on the brain. Researchers point to several possible mechanisms. Aspartame may increase neuroinflammation, which harms memory and learning. Sugar alcohols such as erythritol and sorbitol may disrupt the gut–brain axis. Other evidence suggests some sweeteners can cross the blood–brain barrier and affect neurotransmitters.
“They may be calorie-free, but they’re not consequence-free,” said Dr. Uma Naidoo, a nutritional psychiatrist at Harvard Medical School.
The International Sweeteners Association disputed the conclusions, noting that all of the sweeteners studied remain approved by major regulators including the U.S. Food and Drug Administration and the European Food Safety Authority. “Associations do not prove harm,” the group said.
Still, exposure is widespread. Reporting by The Irish Star found that six of the sweeteners in the study are present in more than 100,000 food products, from sports drinks to children’s snacks. Many appear on ingredient labels under E-numbers such as E951 (aspartame), E954 (saccharin), E950 (acesulfame-K), E968 (erythritol), E420 (sorbitol) and E967 (xylitol). Only tagatose, a naturally derived sweetener, was not associated with memory decline.
Health experts are not urging a return to refined sugar. Instead, they recommend natural alternatives such as honey, dates or maple syrup, as well as whole fruits and spices like cinnamon or carob, which contain fiber and antioxidants.
Artificial sweeteners may cut calories. But as diet drinks and sugar-free snacks flood markets worldwide — especially in regions like the Middle East and North Africa where diabetes rates are rising — researchers say the long-term tradeoff may be sharper than expected.
In a world where “sugar-free” is sold as smart, the new findings raise a difficult question: Are we trading short-term gains for long-term cognitive loss?
