Sugar-free foods and beverages may help your waistline, but they could come at a cost to your brain.
A study from the University of São Paulo in Brazil suggests that artificial sweeteners may speed up cognitive decline — with two groups appearing to face the greatest risk, including people with a disease affecting more than 40 million Americans.
“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,” study author Dr. Claudia Kimie Suemoto said in a press release.
The researchers focused on seven popular sweeteners in particular: aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol and tagatose.
These are commonly added to ultra-processed products marketed as low in calories. Many are also sold separately for use in coffee, tea, cooking and baking.
Aspartame, for example, is found in products like Diet Coke, Diet Pepsi and some sugar-free gums. Acesulfame K is commonly used in diet drinks and low-calorie products, while erythritol is a staple in many keto-friendly and low-carb foods. Saccharin is the primary ingredient in Sweet’N Low.
In the study, six of these sweeteners were associated with faster declines in overall mental performance — particularly memory-related measures. Notably, tagatose was the only one studied that wasn’t linked to faster decline.
Suemoto and her colleagues followed nearly 13,000 52-year-olds living across Brazil for eight years.
They were divided into three groups based on their total reported sweetener intake. The lowest-intake group averaged about 20 milligrams of sweeteners per day, while the highest-intake group averaged 191 milligrams daily.
Throughout the study, the participants took a series of tests measuring mental performance, including how quickly they could recall words, use their short-term memory and process information.
The results? People who consumed the most sweeteners experienced a 62% faster decline in mental performance over the eight-year study than those who consumed the least — even after after accounting for factors that can affect brain health, like age, sex, high blood pressure and heart disease.
The study authors estimated that gap was the equivalent of about 1.6 extra years of aging.
The middle sweetener group wasn’t spared either, with their thinking and memory skills slipping 35% faster than in the lowest-intake group. The researchers estimated that gap was comparable to about 1.3 extra years of aging.
The effects were not the same for everyone. Adults under 60 who consumed the most sweeteners saw faster declines in verbal fluency and overall mental performance compared with those who consumed the least. The researchers didn’t find the same pattern among older participants.
The link was also stronger among people with diabetes, who may rely more on sugar substitutes because they are often advised to limit foods and drinks that can spike blood sugar.
“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,” Suemoto said.
That finding is especially notable because about 40.1 million Americans have diabetes — or roughly 1 in 8 people nationwide.
Still, don’t rush to toss your sweetener packets just yet.
The study had several important limitations. For one, researchers didn’t examine every artificial sweetener on the market, meaning the findings can’t be applied to all sugar substitutes.
The dietary information that the team collected also relied on the participants’ own memory, which may not always be completely accurate.
And because the study was observational, the researchers could only identify a link between higher sweetener consumption and faster mental decline — not prove that the sweeteners themselves caused the changes.
“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.
For now, the study adds to a growing debate over how the choices we make at the grocery store could affect our mental sharpness down the line.
That question is becoming increasingly relevant as about 1 in 10 US adults ages 45 and older report experiencing worsening memory problems, raising concerns about the factors that may contribute to changes in thinking over time.
But sugar substitutes aren’t going anywhere anytime soon.
As Americans look for ways to cut calories and food companies reformulate products to meet changing demands, the use of artificial sweeteners continues to rise.
Today, these alternatives are ubiquitous in the modern food supply, with about 40% of people in the US regularly consuming them.
