SAO PAULO — Adults who consumed the largest amounts of several low- and no-calorie sweeteners experienced faster declines in memory and thinking skills than people with the lowest intake, according to an eight-year observational study of nearly 13,000 adults in Brazil.
The research followed 12,772 adults and evaluated seven sugar substitutes: aspartame, saccharin, acesulfame potassium, erythritol, xylitol, sorbitol and tagatose. The ingredients are commonly found in diet drinks, flavored water, energy drinks, yogurt, desserts and other products marketed as low-calorie or sugar-free.
Participants in the highest-consumption group had a 62% faster rate of overall cognitive decline than those in the lowest group, researchers reported. The difference was estimated to be comparable to about 1.6 additional years of brain aging. For aspartame, the highest intake was roughly the amount contained in one can of diet soda.
The association was strongest among middle-aged adults and appeared in people with and without diabetes. The study did not include every sweetener on the market, and it relied partly on participants reporting what they ate and drank.
Researchers emphasized that the findings show an association and do not prove that sweeteners caused the decline. Diet, diabetes, weight, medication use and other health or lifestyle factors can affect both sweetener use and cognitive health. Additional clinical research is needed before the results can be used to set individual consumption limits.
Sources: TheStreet and the study published in Neurology. Published Aug. 4, 2026; study findings released July 2026.
