Diet Today, Forgetfulness Tomorrow: Sweeteners May Accelerate Brain Aging

Swapping sugar for artificial sweeteners may seem like a smart choice, but this large Brazilian study shows that frequent consumption of these products is associated with faster brain aging. The research followed thousands of people for almost a decade and found a decline in memory and reasoning, especially in younger adults and people with diabetes. The warning is clear: protecting the brain goes far beyond cutting calories.

For many years, artificial sweeteners were seen as a safe alternative to sugar, especially for people with diabetes or those wanting to lose weight. The idea was simple: fewer calories meant better health. However, new research is beginning to show that this swap can have unexpected consequences for the brain, especially when consumption is frequent and prolonged.

A large Brazilian study followed more than 12,000 adults for approximately eight years to understand how the consumption of artificial sweeteners relates to brain health over time.

Researchers observed that people who consumed larger amounts of these sweeteners showed a faster decline in important cognitive functions, such as memory, reasoning, and verbal fluency. This decline was equivalent to about an extra year and a half of brain aging over the study period.

The effects were even more evident in two specific groups: adults under 60 and people with diabetes. This is especially relevant because these groups are often encouraged to replace sugar with artificial sweeteners in their daily lives. Interestingly, in people over 60, this association was not significantly observed, suggesting that age may influence how the brain reacts to these compounds.

To conduct the study, researchers began by collecting detailed information about the participants' diets. Each person answered questionnaires about everything they had consumed in the previous year, including foods, beverages, and processed products containing sweeteners.

From this, participants were divided into groups according to the total amount of sweeteners consumed per day, ranging from very low to high consumption.

In addition to dietary analysis, participants underwent cognitive tests at three different times: at the beginning of the study, in the middle, and at the end of the follow-up. These tests assessed essential skills for daily functioning, such as the ability to quickly find words, remember information after some time, maintain attention, and process information quickly.

In this way, researchers were able to observe not only differences between people, but also how each individual's mental performance changed over the years.

When scientists analyzed the types of sweeteners individually, they found worrying results. High consumption of substances such as aspartame, saccharin, acesulfame potassium, erythritol, sorbitol, and xylitol was associated with a faster decline in cognitive function, especially memory.

Only one sweetener, tagatose, showed no association with cognitive decline. Although the study does not prove that sweeteners directly cause brain damage, it shows a consistent association, even after considering factors such as age, education, disease, and lifestyle.

Researchers emphasize that brain health depends on a combination of factors, not just reducing calories or sugar. A balanced diet, physical activity, adequate sleep, stress management, mental stimulation, and social relationships remain fundamental. The study reinforces the need for caution in the frequent use of artificial sweeteners and suggests that replacing sugar with ultra-processed products may not be the healthiest solution for the brain in the long term.

READ MORE:

The Dark Side of Sweet: Neurocognitive Consequences of Artificial Sweeteners

Thomas Monroe Holland

Neurology. October 7, 2025 issue 105 (7) e214129

DOI: 10.1212/WNL.0000000000214129

Abstract:

Emerging evidence challenges the long-held assumption that artificial sweeteners are safe substitutes for sugar. In this issue of Neurology, Suemoto et al. report that higher intake of low- and no-calorie sweeteners was associated with accelerated decline in global cognition and verbal fluency, equivalent to approximately 1.5 years of brain aging over eight years of follow-up. Associations were particularly strong among adults under 60 and individuals with diabetes, groups often counseled to use these additives. Several sweeteners including aspartame, saccharin, acesulfame-K, erythritol, sorbitol, and xylitol were implicated, while tagatose showed no association with cognitive harm. These findings, supported by emerging mechanistic data linking sweeteners to vascular dysfunction and neuroinflammation, underscore the need to reconsider dietary guidance that substitutes artificial sweeteners for sugar. Neurologists should counsel patients that protecting cognitive health requires an integrated approach optimizing diet, activity, sleep, stress, cognitive stimulation, and social connection while minimizing reliance on synthetic additives.