Ilaria Rosella Pagliaro A major study links daily artificial sweetener use to faster cognitive decline in younger adults, raising new concerns about their real impact on brain health.
They’re marketed as the smarter choice. They sweeten coffee without sugar, dominate the shelves of diet sodas, and have long been recommended to people with diabetes. But artificial sweeteners – from aspartame and saccharin to acesulfame-K and erythritol – may not be as harmless as they appear.
A large-scale study from Brazil, following nearly 13,000 adults over the course of eight years, has found a worrying association: habitual consumption of artificial sweeteners was linked to a faster rate of cognitive decline.
A daily can of diet soda, and sharper decline
The participants, all civil servants, were split into three groups depending on their sweetener intake. Those consuming the most – roughly the equivalent of one can of diet soda a day – experienced a cognitive decline that was 62% faster than those who used very little.
According to the researchers, this accelerated decline amounts to the brain aging an additional 1.6 years over an eight-year span. Almost every sweetener analyzed showed this effect, with one exception: tagatose, a relatively uncommon natural sweetener.
Memory gaps and missing words
Cognitive problems are often assumed to be the burden of old age. But the Brazilian study, published in Neurology, revealed something different: the negative impact of sweeteners appeared only in people under 60.
And the effect was even stronger among participants with diabetes, the very group most likely to use these sugar substitutes. It’s a cruel irony – those avoiding sugar for health reasons might be, without realizing it, harming their brain instead.
The areas most affected were verbal memory – the ability to recall words or recently heard information – and verbal fluency, or the ease of finding the right word quickly. In real life, that translates into more frequent memory blanks, more of those frustrating “tip-of-the-tongue” moments, and greater difficulty expressing oneself clearly.
Signals we all recognize from time to time. But when they become frequent, they start to erode the fabric of everyday life.
Correlation, not proof
It’s important to stress: there’s no definitive proof that sweeteners cause cognitive decline. This is a correlation, not a clear-cut cause. And the study relied on food questionnaires filled out by participants, which are notoriously imprecise.
Not all sweeteners on the market were analyzed either – stevia and sucralose, for instance, weren’t included. Industry groups such as the British Soft Drinks Association and the International Sweeteners Association were quick to emphasize that regulatory bodies like the FDA and EFSA continue to consider artificial sweeteners safe within the established daily limits.
Yet even the World Health Organization recently advised against using sweeteners for long-term weight management. Clearly, the debate is far from settled.
What might be happening inside the body
So how exactly could sweeteners affect the brain? Researchers suspect two main mechanisms.
One involves the gut microbiome: sweeteners may disrupt the balance of beneficial bacteria, triggering inflammation that eventually impacts the brain.
The second is about the disconnect between taste and calories. When the brain perceives sweetness, it expects energy. But with sweeteners, that energy never arrives. Over time, this mismatch could confuse the body’s regulation of hunger, metabolism – and even cognitive function.
What now?
No one is calling for an outright ban on artificial sweeteners. But if you’re using them every single day, even just in coffee or tea, it might be worth reconsidering.
Lead author Dr. Suemoto suggests natural alternatives – honey, maple syrup, coconut sugar, or even applesauce – always in moderation. Her team is already planning new research using neuroimaging, to see if habitual sweetener consumption leaves visible marks on the brain.
In the meantime, the message is simple: if the goal is to protect health, maybe it’s time to give our brain the same care we give to our waistline.
Source: Neurology
