Artificial sweeteners may speed up brain ageing and raise health risks, research shows

For years, artificial sweeteners have been considered the perfect alternative to sugar. These synthetic substitutes provide sweetness with little or no calories and are widely used in foods and beverages to help reduce calorie intake. However, a growing body of research suggests that artificial sweeteners may be linked to dementia, cancer, and other health conditions.

In a study published in the journal Neurology, researchers revealed a concerning link between the consumption of several commonly used artificial sweeteners and accelerated cognitive decline. This type of decline is an early warning sign and major risk factor for dementia.

Dementia is a broad term describing a decline in mental abilities severe enough to affect daily life. It involves the gradual loss of cognitive functions such as memory, reasoning, language, and problem-solving.

Alzheimer's disease is the most common form of dementia, though there are several other types. Dementia results from damage to brain cells and is generally progressive and irreversible.

The study was part of the Brazilian Longitudinal Study of Adult Health, which follows public workers' health over time.

It included 12,772 civil servants aged 35 to 74, with an average age of 52. Most participants were women, and over 40 per cent were Black or mixed race. For about eight years, researchers tracked their diets and tested their thinking skills.

Food frequency questionnaires

At the start of the study, participants completed detailed food frequency questionnaires that captured their intake of foods and beverages containing low- and no-calorie sweeteners.

The study specifically examined seven sweeteners: Aspartame, Saccharin, Acesulfame-K, Erythritol, Xylitol, Sorbitol, and Tagatose.

Based on total daily sweetener consumption, participants were grouped into low, moderate, and high intake categories.

Low intake was defined as around 20 milligrams per day, moderate as 64 milligrams, and high as approximately 191 milligrams—roughly the amount of aspartame in a single can of diet soda.

Throughout the study period, participants underwent standardised tests to assess key areas of cognitive function, including memory, verbal fluency, working memory, processing speed, and overall cognition.

Participants in the highest intake group experienced a 62 per cent faster rate of cognitive decline compared to those in the lowest intake group. This level of decline was equivalent to about 1.6 additional years of brain ageing.

Those in the moderate intake group saw a 35 per cent faster decline, equivalent to around 1.3 years of extra brain ageing. The most affected areas of cognition were verbal memory and verbal fluency, both of which are often among the first cognitive functions to deteriorate in the early stages of dementia.

Faster cognitive decline

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Not all sweeteners had the same effect.

The study found that six of the seven sweeteners—Aspartame, Saccharin, Acesulfame-K, Erythritol, Sorbitol, and Xylitol—were significantly associated with faster cognitive decline. Only Tagatose showed no such link, suggesting it may be a safer alternative in terms of brain health.

Age appeared to be an important factor in how these sweeteners affected the brain. The association between sweetener consumption and cognitive decline was especially strong among participants under the age of 60.

Among older adults aged 60 and above, no significant association was observed. This suggests that midlife exposure to high levels of artificial sweeteners may be particularly harmful to long-term brain health.

Greater declines

The study also found that people with diabetes were more vulnerable to the negative cognitive effects of these sweeteners. Diabetic participants experienced greater declines in memory and overall cognitive performance compared to non-diabetics, highlighting a potentially higher risk in already at-risk populations.

The authors of the study were careful to note that their findings are observational, meaning they cannot prove that sweeteners cause cognitive decline.

However, the strength and consistency of the associations—along with the fact that the results were adjusted for a wide range of lifestyle and demographic factors—make the findings compelling.

The study's methodology was robust, and while it relied on self-reported dietary data, the results align with growing concerns in other recent research about how artificial sweeteners may impact metabolic and neurological health.

Further research

Although the biological mechanisms were not explored in depth in this study, the authors called for further research into how artificial sweeteners might influence brain health through pathways such as insulin resistance, inflammation, or the gut-brain axis. These potential mechanisms, if confirmed, could reshape public health guidance around sweetener use.

While more research is needed to fully understand the risks, this study suggests that artificial sweeteners are not as neutral as once thought, and that regular, high intake may come with cognitive costs.

A growing body of research supports concerns that artificial sweeteners may not be as safe as once believed. For example, a large-scale study involving over 100,000 adults in France found that higher consumption of artificial sweeteners—particularly aspartame, acesulfame potassium, and sucralose—was linked to an increased risk of cardiovascular disease.

Specifically, aspartame intake was associated with a 17 per cent higher risk of cerebrovascular events, while acesulfame potassium and sucralose were each linked to a 31 per cent increased risk of coronary heart disease.

In the same cohort, researchers also observed a 13 per cent increased risk of overall cancer associated with higher artificial sweetener intake, further raising concerns about the long-term health impacts of these common sugar substitutes.