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Study associates artificial sweeteners with faster cognitive decline and raises debate about “zero sugar” drinks.
In 2025, a Brazilian study published online on September 3 and recorded in the October 7 edition of the scientific journal Neurology placed a common habit of millions of people at the center of the debate: the consumption of products with low or no-calorie sweeteners. The research, conducted with data from 12,772 Brazilian adults followed for about eight years, evaluated substances such as aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose, found in beverages, yogurts, low-calorie desserts, and other ultra-processed foods.
The most striking data is straightforward: after adjustments for factors such as age, sex, hypertension, and cardiovascular disease, participants with the highest total consumption of these sweeteners showed a 62% faster decline in memory and thinking skills, equivalent to about 1.6 additional years of cognitive aging compared to the lowest consumption group.
The study does not claim that sweeteners cause memory loss, but it points to a relevant association, especially in people under 60 and in participants with diabetes, reinforcing that science still needs to better investigate the possible long-term effects of these sugar substitutes on the brain.
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Study followed over 12,000 Brazilians for eight years to analyze effects on the brain
The research used data from a large Brazilian population study focused on cardiovascular and neurological health, following adults over years with periodic evaluations.
Participants underwent cognitive tests that measure different brain functions, such as memory, processing speed, and planning ability.
By cross-referencing this data with dietary habits, researchers identified a pattern: the higher the consumption of artificial sweeteners, the more accelerated the cognitive decline observed over time.
This type of study is called observational longitudinal, meaning it follows people over time to identify associations between behavior and health outcomes.
Faster cognitive decline does not mean direct cause, but raises scientific alert
A fundamental point to understand the results is the difference between association and causality. The study does not prove that artificial sweeteners cause memory loss or brain aging. What it shows is that there is a consistent statistical relationship between high consumption and worse cognitive performance over time.
This means that other factors may be involved, such as lifestyle, general diet, health conditions, or behavior.
Still, when a pattern appears in a large sample followed for years, it becomes considered relevant enough for further investigation.
Artificial sweeteners were already being studied for metabolic and intestinal effects
Even before this study, artificial sweeteners were already on the scientific radar for other reasons. Previous research analyzed possible effects of these compounds on:
- glucose metabolism,
- insulin response,
- gut microbiota.
Some studies suggest that certain sweeteners can alter the balance of bacteria in the gut, a process known as dysbiosis.
As the gut communicates with the brain via the gut-brain axis, this alteration has begun to be investigated as a possible indirect pathway for cognitive impacts.
Gut microbiota emerges as one of the hypotheses to explain effects on the brain
One of the most discussed hypotheses currently involves the gut microbiota. The gut hosts trillions of microorganisms that participate in the production of important chemical substances for the body, including neurotransmitters and inflammatory compounds.
Changes in this ecosystem can influence processes such as:
- systemic inflammation,
- mood regulation,
- cognitive function.
If artificial sweeteners significantly modify the microbiota, this can indirectly affect the brain. However, this mechanism is still being investigated and is not considered conclusive.
Low-grade chronic inflammation is also pointed out as a possible link
Another possible pathway involves inflammation. Science already recognizes that low-grade chronic inflammation is associated with various conditions, including cardiovascular diseases, diabetes, and cognitive decline.
Some studies hypothesize that certain dietary patterns, including high consumption of ultra-processed foods and sweeteners, may contribute to this type of inflammation.
This inflammation, in turn, can affect brain function over time.
Consumption of “zero” drinks grew with the search for sugar reduction
The study’s context also helps understand its relevance. In recent years, there has been a significant increase in the consumption of products with artificial sweeteners, especially “zero sugar” drinks.
This growth is linked to the attempt to reduce sugar consumption, control weight, and decrease the risk of metabolic diseases.
For many consumers, zero-sugar soda has come to be seen as a healthier choice. The study does not invalidate this choice, but it shows that it may not be neutral from a scientific point of view.
Results require caution and do not indicate the need to eliminate sweeteners immediately
The researchers themselves emphasize that the results should be interpreted with caution. The study does not recommend that people immediately stop consuming artificial sweeteners, nor does it state that these products are dangerous in themselves.
The main impact is to raise a scientific question that still needs further investigation. Controlled clinical trials, which can test cause and effect more directly, are still needed to confirm these findings.
Other lifestyle factors also influence cognitive health
Brain health does not depend on a single factor. Various elements influence the risk of cognitive decline, including:
- level of physical activity,
- sleep quality,
- overall diet,
- management of chronic diseases.
Therefore, analyzing only an isolated component can lead to incomplete interpretations.
Scientific debate tends to grow with new studies on diet and the brain
The study published in Neurology is part of a larger trend. Science has increasingly focused on understanding how diet influences the brain, going beyond the traditional impact on weight and metabolism.
This field involves areas such as:
- neuroscience,
- nutrition,
- microbiology,
- psychiatry.
The idea that what one eats can influence memory, mood, and cognition is gaining traction, but it is still under scientific development.
Zero-sugar soda is no longer just a dietary choice and enters the debate on mental and cognitive health
The main effect of this type of study is not to create immediate fear, but to change the type of questions people ask.
Before, the discussion was: sugar or sweetener? Now, it starts to include: what is the long-term impact of these choices on the brain? This change broadens the debate and makes consumption more conscious.
Now the direct question is: if “zero sugar” drinks can be associated with changes in the brain over the years, to what extent can choices considered healthy today have effects that science is only just beginning to understand?
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