Global: Artificial sweeteners, widely marketed as healthier alternatives to sugar in diet drinks and low-calorie foods, may be associated with faster cognitive decline in middle-aged adults, according to a new study published in the journal Neurology by the American Academy of Neurology. While the findings do not establish a cause-and-effect relationship, researchers say the results add to growing evidence that long-term consumption of certain sugar substitutes could have implications for brain health.
The study found that adults under the age of 60 who consumed the highest amounts of artificial sweeteners experienced a significantly faster decline in memory and thinking abilities than those who consumed the least. Researchers emphasised, however, that further studies are needed before drawing definitive conclusions about the impact of artificial sweeteners on cognitive health.
Eight-year study tracked more than 12,700 adults
The research followed 12,772 adults with an average age of 52 years over a period of approximately eight years.
Participants completed detailed food frequency questionnaires that estimated their consumption of seven commonly used sweeteners:
- Aspartame
- Saccharin
- Acesulfame K
- Erythritol
- Xylitol
- Sorbitol
- Tagatose
Researchers assessed participants’ memory and cognitive abilities at the beginning, midway point and end of the study. By comparing dietary habits with cognitive performance over time, they examined whether higher intake of artificial sweeteners was associated with changes in brain function.
Faster cognitive decline seen in middle-aged adults
The study found that participants under the age of 60 who consumed the highest quantities of artificial sweeteners experienced a 62 per cent faster decline in memory and cognitive function compared with those who consumed the lowest amounts.
Researchers estimated that this difference was roughly equivalent to an additional 18 months of brain ageing.
Even participants with moderate consumption of artificial sweeteners showed a 35 per cent faster decline in cognitive performance than low consumers, suggesting that the association was not limited to only the highest intake group.
However, the researchers stressed that the findings demonstrate an association and do not prove that artificial sweeteners directly cause memory loss or cognitive decline.
Stronger association observed among people with diabetes
The relationship between artificial sweetener consumption and cognitive decline appeared to be strongest among participants living with diabetes.
Lead author Dr Claudia Kimie Suemoto from the University of São Paulo noted that people with diabetes often replace sugar with low- or no-calorie sweeteners to help manage blood glucose levels.
She said that while artificial sweeteners are generally promoted as healthier substitutes for sugar, the findings suggest that some of these products may have long-term effects on brain health that require closer scientific investigation.
Researchers believe this observation is particularly relevant because individuals with diabetes are among the highest consumers of sugar substitutes.
Why no similar effect was seen in older adults
Interestingly, the researchers did not identify a statistically significant association between artificial sweetener intake and cognitive decline among participants aged 60 years and above.
However, experts cautioned against interpreting this as evidence that artificial sweeteners become harmless with age.
According to Dr Andrew Budson, Lecturer in Neurology at Harvard Medical School, cognitive decline varies much more widely among older adults, making it more difficult to detect relatively small differences in scientific studies.
In other words, the absence of a statistically significant association does not necessarily mean that no relationship exists.
Artificial sweeteners are found in many everyday foods
Although diet soft drinks are the products most commonly associated with artificial sweeteners, researchers pointed out that these ingredients are present in a wide variety of processed foods.
Common sources include:
- Diet soft drinks
- Sugar-free fruit juices
- Protein bars
- Sugar-free desserts
- Low-calorie yoghurts
- Chewing gum
- Flavoured beverages
- Sugar-free biscuits and snacks
- Packaged “diet” foods
Because artificial sweeteners are used extensively in processed products, consumers may unknowingly consume them from multiple sources throughout the day.
Researchers urge moderation, not alarm
The researchers stressed that the study was observational, meaning it identified an association rather than proving that artificial sweeteners directly caused cognitive decline.
Other factors such as overall diet, physical activity, existing medical conditions, sleep quality and lifestyle habits may also influence long-term brain health.
Scientists say additional research is needed to determine whether individual sweeteners differ in their effects on cognition and whether reducing artificial sweetener intake can lower the risk of memory decline.
Healthy lifestyle remains the best approach
Health experts continue to recommend focusing on overall dietary quality instead of relying heavily on either sugar or artificial sweeteners.
Simple lifestyle measures known to support brain health include:
- Eating a balanced diet rich in fruits and vegetables
- Choosing whole grains instead of refined carbohydrates
- Limiting ultra-processed foods
- Exercising regularly
- Managing diabetes, blood pressure and cholesterol
- Getting adequate sleep
- Avoiding smoking and excessive alcohol consumption
Experts also advise consumers to read food labels carefully, particularly if they frequently purchase products labelled as “diet”, “low-calorie” or “sugar-free”.
While artificial sweeteners remain useful for reducing sugar intake in certain situations, the latest findings suggest they should be consumed in moderation until more conclusive evidence becomes available regarding their long-term effects on brain health.
Conclusion
The new study contributes to a growing body of research exploring how dietary habits influence cognitive function over time. Although it does not establish that artificial sweeteners cause memory decline, it raises important questions about their long-term use, especially among middle-aged adults and people with diabetes.
Until further research provides clearer answers, experts recommend a balanced, minimally processed diet and moderation in the consumption of both sugar and artificial sweeteners as part of an overall strategy for maintaining good brain health.