This trend was only apparent in participants under 60 years old, and was especially strong in participants with diabetes.
When the researchers looked closer at the individual sugar substitutes, they found that higher intake of six of the seven—aspartame, saccharin, acesulfame-k, erythritol (the least consumed), sorbitol (the most consumed), and xylitol—was also tied to faster cognitive declines, particularly memory and verbal fluency. Tagatose was the only exception.
What this means for you
Ultimately, this study suggests that consuming sugar substitutes over an extended period of time is associated with worse cognitive health. Importantly, this association doesn’t necessarily signify that sugar substitutes cause cognitive decline. Rather, it means the two variables are correlated. “It doesn’t mean the study is irrelevant, but it’s an important distinction,” Byrne says.
Hypothesizing a possible explanation for the link between higher sugar substitute intake and accelerated cognitive decline, the researchers posited that sugar substitutes might produce toxic metabolites during digestion, which, in turn, have a damaging effect. Basically, the authors are saying this link “could be because these sweeteners get broken down into other compounds in the body, and those compounds may cause inflammation in the brain,” Byrne explains. Fundamentally, she notes, “the thing about studies like this one, that look at correlations between certain behaviors (in this case, consuming artificial sweeteners) and certain health outcomes, is that it’s impossible to know what the mechanism is.”
What’s more, the study isn’t the first to raise the alarm regarding the impact of sugar substitutes on cognitive function. Previous studies have also found links between both artificially sweetened products (like soft drinks) and individual sugar substitutes (like sucralose and saccharin) and cognitive issues, including reduced memory and executive function and increased dementia risk.
With all this said, these findings don’t mean that sugar substitutes are bad for you across the board, or that you should try to cut them out entirely. Besides, that would be tough, or even impossible to do, considering how prevalent they are in food and drink products, particularly low-calorie ultraprocessed items like soda, light yogurt, flavored water, and energy drinks. Three of the seven sugar substitutes involved in the study—erythritol, sorbitol, and xylitol—belong to a category known as sugar alcohols, artificial sweeteners that can be found in sweet treats like candy, ice cream, baked goods, and protein bars (and can cause digestive symptoms), for example.
“If someone is drinking several diet sodas or other artificially sweetened things per day, they might take this as a sign to cut back,” Byrne says. “But I don’t think this is a reason for everyone to panic and swear off artificial sweeteners completely if they enjoy them on occasion.”
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