Artificial sweeteners are often used as a healthier alternative to sugar.
They are found in many low-calorie and sugar-free foods and drinks.
But a new study from Brazil suggests that some of these sugar substitutes may have unexpected side effects on the brain.
The study was published in Neurology®, the medical journal of the American Academy of Neurology. It looked at how seven common low- and no-calorie sweeteners might affect brain health over time.
The researchers found that people who consumed the most artificial sweeteners had faster declines in memory and thinking skills than those who consumed the least. This effect was even stronger in people with diabetes.
The sweeteners studied were aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose. These ingredients are often found in diet soda, flavored water, energy drinks, yogurt, and low-calorie desserts. Some are also sold as sugar-free sweeteners for coffee or tea.
Dr. Claudia Kimie Suemoto from the University of São Paulo led the study. She said that while artificial sweeteners are seen as a good alternative to sugar, the study suggests they may harm brain health over time.
The study involved 12,772 adults from Brazil. The average age was 52, and researchers followed them for about eight years. At the beginning of the study, participants filled out food questionnaires about what they had eaten in the past year. Based on their answers, researchers divided them into three groups: low, medium, and high sweetener users.
People in the lowest group consumed about 20 milligrams of sweeteners per day. Those in the highest group consumed around 191 milligrams per day. For example, one can of diet soda has about this amount of aspartame. Among the sweeteners, sorbitol had the highest daily intake, with people consuming an average of 64 milligrams a day.
Participants also took memory and thinking tests at the start, middle, and end of the study. These tests measured skills like memory, language, and how fast they could process information.
After adjusting for age, sex, high blood pressure, and heart problems, the results showed that people in the highest group had memory and thinking declines that were 62% faster than those in the lowest group. People in the middle group declined 35% faster. In simple terms, this means their brains aged about 1.6 and 1.3 years faster, respectively.
The results were more noticeable in people under the age of 60. Younger people who consumed more sweeteners showed faster declines in verbal fluency and overall brain function. For people over 60, there was no strong link. The effect was also stronger in people with diabetes.
When the researchers looked at each sweetener separately, they found that most were linked to faster memory decline—especially aspartame, saccharin, acesulfame-K, erythritol, xylitol, and sorbitol. Only tagatose showed no link to memory problems.
Dr. Suemoto said that people with diabetes may be more likely to use artificial sweeteners, which could be why the effects were stronger in this group. She also called for more studies to confirm the results and to test whether natural sugar substitutes like honey, maple syrup, applesauce, or coconut sugar might be safer options.
One limitation of the study was that not all sweeteners were included, and participants had to remember and report what they ate, which may not be completely accurate.
The study was supported by several scientific and government agencies in Brazil. While the research does not prove that artificial sweeteners cause memory loss, it raises important questions about how these common ingredients might affect long-term brain health.
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The study is published in Neurology.
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