Artificial sweeteners are often marketed as a healthier alternative to sugar, especially for people trying to cut calories or manage conditions like diabetes.
But a new study suggests that regularly consuming some of these sugar substitutes could come with unexpected risks for long-term brain health.
The research, published in Neurology, followed more than 12,700 adults in Brazil for an average of eight years.
Participants were around 52 years old at the start of the study and were asked to complete detailed questionnaires about their diets, including how much low- and no-calorie sweeteners they consumed.
Researchers then tracked their thinking and memory skills with cognitive tests taken at the beginning, middle, and end of the study.
Seven sweeteners were studied: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose.
These are commonly found in products such as diet sodas, flavored waters, energy drinks, low-calorie desserts, yogurt, and other ultra-processed foods. They are also sold as standalone sweeteners.
When researchers divided participants into groups based on their consumption, they found striking differences.
Those who consumed the most artificial sweeteners—an average of 191 milligrams per day, about the amount of aspartame in one can of diet soda—showed a decline in thinking and memory skills that was 62% faster than people who consumed the least.
This decline was roughly the same as aging an extra 1.6 years. People in the middle consumption group declined about 35% faster, the equivalent of 1.3 years of extra aging.
The effects were particularly strong in people under 60, who showed faster declines in verbal fluency and overall cognition if they consumed high amounts of sweeteners.
The link was also stronger in participants with diabetes, who are more likely to rely on sugar substitutes to manage blood sugar.
When the team looked at specific sweeteners, they found that aspartame, saccharin, acesulfame-K, erythritol, xylitol, and sorbitol were all linked to faster cognitive decline, especially in memory-related areas.
Only tagatose showed no association with worsening brain function.
“Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar,” said study author Dr. Claudia Kimie Suemoto from the University of São Paulo. “But our findings suggest that certain sweeteners may have negative effects on brain health over time.”
The researchers cautioned that the study shows a link, not proof of cause and effect. They also noted limitations, such as relying on participants’ self-reported diets and not including every type of artificial sweetener. Still, the results raise important questions about the long-term safety of these widely used products.
Dr. Suemoto emphasized the need for further research to confirm the findings and to test whether natural sugar alternatives—like honey, maple syrup, coconut sugar, or applesauce—might be safer substitutes.
For now, the results add weight to the idea that cutting back on both sugar and artificial sweeteners may be one of the best ways to protect not only heart health, but brain health as well.
If you care about brain health, please read studies about inflammation that may actually slow down cognitive decline in older people, and low vitamin D may speed up cognitive decline.
For more health information, please see recent studies about common exercises that could protect against cognitive decline, and results showing this MIND diet may protect your cognitive function, prevent dementia.
