Artificial sweeteners in yoghurts and fizzy drinks may speed up cognitive decline by 62 per cent, equivalent to ageing the brain by 1.6 years, researchers say.
People who consumed the most artificial sweeteners such as aspartame and saccharin showed quicker declines in memory and thinking skills, based on an eight-year study of 12,772 Brazilian civil servants.
The effect was most evident in adults under 60, pointing to possible long-term harm from low- and no-calorie sweeteners.
Researchers from the University of São Paulo tracked participants with an average age of 52. They completed food and drink questionnaires and took cognitive tests measuring word recall and verbal fluency.
Those with the highest sweetener intake declined 62 per cent faster in these skills than those with the lowest.
“Daily consumption of LNCs was associated with accelerated decline in memory, verbal fluency and global cognition,” the researchers reported.
LNCs (low- and no-calorie sweeteners) are sugar substitutes that provide sweetness without calories.
The study examined seven sweeteners – aspartame, saccharin, acesulfame K, erythritol, sorbitol, xylitol and maltitol – commonly found in low-calorie desserts, flavoured water and energy drinks.
Claudia Kimie Suemoto, lead author from the University of São Paulo, said: “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.”
The effect was not seen in participants over 60, suggesting middle-aged adults may need more encouragement to cut back on sweeteners. Researchers suggested tagatose, a natural sweetener, or alternatives such as honey or maple syrup.
Previous studies have linked artificial sweeteners to higher risks of type 2 diabetes, cancer, heart problems, depression and dementia, as well as damage to the gut wall.
Industry groups questioned the findings. Gavin Partington, director general of the British Soft Drinks Association, said: “By the authors’ own admission, this study cannot prove cause.
“Non-sugar sweeteners are safe, according to all leading health authorities in the world, and that’s why they have been used in a vast array of food, medicine, dental and drinks products for many decades.
“Their use in soft drinks has helped UK manufacturers to remove just under three-quarters of a billion kilograms of sugar from product since 2015.”
The International Sweeteners Association (ISA) said there is an “established scientific consensus” that sweeteners are safe.
“This research is an observational study, which can only show a statistical association, not a direct cause-and-effect relationship.
“The reported link between sweetener consumption and cognitive decline does not prove that one causes the other.”