Low-calorie artificial sweeteners linked to faster cognitive decline

New research finds that some artificial sweeteners can negatively impact long-term brain health. These include aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose, which the study linked to a 1.6-year decline in cognition, 62% faster among people consuming the highest amounts compared to a low-consumption group. 

Researchers monitored the seven low- and no-calorie sweeteners used in ultra-processed foods, such as flavored water, soda, energy drinks, yogurt, and low-calorie desserts. They found that those who consumed the most of these sweeteners from food and beverages had a faster decline in thinking and memory skills than those on the lower end.

The publication in the American Academy of Neurology tracked 12,772 adults, aged 52 on average, across Brazil for an average of eight years.

Notably, the study found the link between sweeteners and cognitive decline to impact those under 60, but not older adults. The link was stronger in those with diabetes than those without.

However, no link was detected between tagatose and cognitive decline.

The researchers concede that while their research found these links, it does not prove that sweeteners cause cognitive decline.

Responding to the study, Laurent Oger, director general at the International Sweeteners Association says the observational study can only show a statistical association, not cause-and-effect relationship. “The results are inconsistent across different age groups and varied by diabetes status, which raises questions about biological plausibility,” he adds.

Study methods and details

Participants revealed what they consumed over the past year in a questionnaire at the start of the study. Researchers then divided them into groups based on the total levels of artificial sweetener consumption.

The highest group consumed on average 191 mg/day, which is about a can of diet soda. The lowest group consumed 20 mg/day. The researchers note that sorbitol was most consumed at 64 mg/day on average.

Cognitive tests were carried out at the start, middle, and end of the study, looking at memory, language, and thinking skills. They also examined verbal fluency, working memory, word recall, and processing speed.

Factors like age, sex, high blood pressure, and cardiovascular disease were adjusted before drawing the conclusions.

While the highest consumption group had a 62% faster cognitive decline, the middle group was 35% faster than the lowest group, equivalent to approximately 1.3 years of aging.

Oger cautions: “The study relies on a self-reported method for dietary data collected only once at baseline 8 years ago, which is often inaccurate, can introduce significant bias, and does not consider changes in dietary habits and product formulations over time.”

“Furthermore, all sweeteners were aggregated in a single value from both high-intensity sweeteners and polyols, while we know they all have very different properties and approved use levels. In practice, the combined sweetener intake was dominated by polyols that are used in higher quantities, while the intake of aspartame, acesulfame-K and saccharin was very low even for the high consumption group (at the order of 1-2% of the respective Acceptable Daily Intakes).”

He points out that these factors point to a high chance of floor effects that may bias results.

Not all sweeteners

Aspartame, saccharin, acesulfame-k, erythritol, sorbitol, and xylitol were linked to faster cognitive decline, especially memory.

“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,” says study author Claudia Kimie Suemoto, MD, Ph.D., at the University of São Paulo in Brazil.

“While we found links to cognitive decline for middle-aged people both with and without diabetes, people with diabetes are more likely to use artificial sweeteners as sugar substitutes.”

She calls for more research to confirm the study findings and to explore whether sugar alternatives such as applesauce, honey, maple syrup, or coconut sugar are more effective.

The study authors say one limitation is that not all artificial sweeteners were examined, plus information about diet was reliant on reports from participants who may not accurately remember everything. Oger underlines global health authorities have consistently confirmed the safety of low/no calorie sweeteners based on scientific evidence, not a single study.