A new study has found that people who consume a lot of low- and no-calorie sweeteners—like those used in diet sodas, sugar-free gum, and many “light” products—may experience faster decline in memory and thinking abilities.
This research, published in the journal Neurology, raises questions about whether these sugar substitutes are really a safe alternative to sugar when it comes to long-term brain health.
The study was done by scientists at the University of São Paulo in Brazil and followed more than 12,000 adults over eight years. All participants were part of a large research project called the Brazilian Longitudinal Study of Adult Health.
At the start, everyone was at least 35 years old. Researchers asked them detailed questions about their eating habits and calculated how much of seven different artificial sweeteners each person consumed, including aspartame, saccharin, erythritol, xylitol, and others.
On average, people in the study consumed about 92 milligrams of these sweeteners per day.
The researchers found that for people under the age of 60, those who consumed the most artificial sweeteners had a faster decline in two key areas of brain function: verbal fluency (how quickly and clearly someone can speak and find words) and overall cognitive ability (general thinking skills, including memory, focus, and problem-solving).
When the researchers looked at older adults (age 60 and above), the results were a little different. In this group, there wasn’t a clear link between how many sweeteners they consumed and how their thinking skills changed over time.
But for people with and without diabetes, high sweetener intake still seemed to be linked to a quicker decline in memory and thinking.
The sweeteners most strongly linked to faster brain decline were aspartame, saccharin, acesulfame K, erythritol, sorbitol, and xylitol. These are commonly found in products like diet drinks, sugar-free candies, chewing gum, protein bars, and even some medicines.
One of the study authors, Dr. Claudia Kimie Suemoto, explained that although these sugar substitutes are often marketed as healthier choices for people watching their weight or blood sugar levels, this study shows that they may have unexpected downsides for the brain.
According to Suemoto, “Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar; however, our findings suggest certain sweeteners may have negative effects on brain health over time.”
It’s important to note that this was an observational study, meaning it can’t prove that artificial sweeteners directly cause cognitive decline. Other factors might also play a role, such as general diet quality, exercise, or overall health.
Still, the findings are strong enough to suggest that more research is needed, and that people should be cautious about using large amounts of these sweeteners, especially younger adults who may be consuming them daily over long periods.
In conclusion, this study adds to growing concerns about how artificial sweeteners may affect our health—not just our weight or blood sugar, but also our brain. Until more is known, it may be wise to limit your intake of low- and no-calorie sweeteners and focus on whole, unprocessed foods whenever possible.
The study is published in Neurology.
Copyright © 2025 Knowridge Science Report. All rights reserved.
