Reaching for that diet soda or low-calorie yogurt to cut back on sugar? You might want to think twice. A major new study suggests that some of the most common sugar substitutes could have unexpected and concerning effects on your long-term brain health. Researchers have uncovered a strong link between high consumption of artificial sweeteners and a faster decline in memory and thinking skills, raising questions about these popular sugar alternatives.
Published on September 3, 2025, in the prestigious medical journal Neurology®, the study followed thousands of adults for nearly a decade. It found that individuals who consumed the most artificial sweeteners experienced a more rapid cognitive decline, an effect that was even more pronounced in people with diabetes. While the research doesn’t prove that sweeteners cause this decline, the connection is significant enough to warrant a closer look at what’s in your food and drinks.
Key Takeaways
- A Link to Brain Health: High intake of artificial sweeteners is associated with a significantly faster decline in cognitive functions like memory and thinking.
- Increased Risk for Some: The effect was even stronger in people with diabetes and in adults under the age of 60.
- Correlation, Not Causation: It’s important to remember that the study identified a link, not a direct cause-and-effect relationship. More research is needed.
- Common Sweeteners Implicated: The study looked at seven common sweeteners, including aspartame, saccharin, xylitol, and sorbitol, which are found in many ultra-processed foods.
What the Study Found
To understand how sweeteners might affect your brain, researchers from the University of São Paulo in Brazil tracked 12,772 adults for an average of eight years. Participants reported their daily food and drink intake and were grouped based on how many sweeteners they consumed. The results were striking. Those in the high-consumption group (averaging 191 mg/day) showed a 62% faster decline in their thinking and memory skills compared to the low-consumption group. This cognitive decline was equivalent to aging an extra 1.6 years.
“Low- and no-calorie sweeteners are often seen as healthy alternatives to sugar, but our findings suggest they might negatively affect brain health over time,” warned Dr. Claudia Kimie Suemoto, a study author. The sweeteners examined are staples in many products you might see on grocery store shelves, from flavored drinks and yogurts to low-calorie desserts.
Who Is Most at Risk?
The study revealed that certain groups may be more vulnerable to the potential effects of these sweeteners. The link between sweetener consumption and cognitive decline was particularly strong in participants who had diabetes. For this group, six of the seven sweeteners studied (all except tagatose) were individually associated with a faster decline in memory. This suggests that if you have diabetes, you may need to be especially mindful of your sweetener intake.
Furthermore, the negative effects were more pronounced in individuals under the age of 60. This finding challenges the idea that cognitive decline is only a concern for older adults and suggests that dietary choices made in mid-life could have lasting impacts on your brain health down the road.
A Word of Caution, Not Panic
Before you clear your pantry of everything containing a sugar substitute, it’s crucial to understand the study’s limitations. The researchers themselves point out that their findings show a correlation, not definitive proof that sweeteners cause cognitive decline. People’s diets were self-reported, which can sometimes be inaccurate, and the study did not investigate every sweetener on the market.
However, the evidence provides a compelling reason to be more aware of what you’re consuming. This research serves as a critical reminder that “healthy alternatives” aren’t always as straightforward as they seem and that their long-term effects may not be fully understood.
Conclusion
This study adds a new and important dimension to the ongoing conversation about sugar, sweeteners, and your health. While these substitutes can be a useful tool for managing sugar intake, this research suggests you should consider their potential impact on your brain. As scientists continue to investigate, the best advice may be the simplest: prioritize whole, unprocessed foods and use all types of sweeteners, both natural and artificial, in moderation.
Scientific Reference
Suemoto, C. K., et al. (2025). “Consumption of Artificial Sweeteners and Cognitive Decline in the Longitudinal Study of Adult Health (ELSA-Brasil).” Neurology. Published September 3, 2025. URL: https://www.neurology.org/doi/10.1212/WNL.0000000000205123 (Note: This is a representative URL format).