Artificial sweeteners may carry unexpected risks for brain health, a new study claims.
A study published in Neurology examined the diets of more than 12,700 adults in Brazil, and found that those who consumed the highest amounts of low- or no-calorie sweeteners experienced faster declines in memory and thinking skills over an eight-year period.
The effect was particularly pronounced among people with diabetes and those under 60.
The researchers assessed seven sweeteners commonly found in diet sodas, flavoured waters, yoghurts and low-calorie desserts: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose.
Of these, all except tagatose were linked to cognitive decline, especially in memory and verbal fluency.
Participants were divided into three groups based on their intake. Those consuming the most – around 191 milligrams a day, the equivalent of a single can of diet soda for aspartame – showed cognitive decline 62 per cent faster than those consuming the least, roughly equal to an extra 1.6 years of ageing.
“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,” said study author Prof Claudia Kimie Suemoto of the University of São Paulo.
“Previous research had linked artificial sweeteners to conditions like diabetes, cancer, cardiovascular disease and depression, but their potential impact on cognition had not been investigated.”
One of the more surprising results was that the link appeared only in adults younger than 60.
“I had expected the association to be more evident in older adults, since they are at higher risk of dementia and cognitive impairment,” Suemoto said. “Instead, our results suggest that midlife exposure to sweeteners may be particularly harmful, which is important because midlife is a critical period for setting the trajectory of brain health.”
The findings do not prove that sweeteners directly cause cognitive decline. Factors such as self-reported diet and the absence of all types of sweeteners in the study are limitations.
Still, Suemoto said the results warrant caution and further research, including brain imaging and mechanistic studies of gut health and inflammation.
Her team is already working on neuroimaging studies to understand what could be causing the link, the results of which are not yet available.
“More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, may be effective alternatives,” Suemoto said.
About our expert
Claudia Suemoto is an assistant professor at the University of São Paulo, Brazil. She's also a trained physician whose research has been published in journals such as The Lancet, Nature Neuroscience and The Journal of Alzheimer's Disease.
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