Artificial sweeteners found in Diet Coke and similar beverages might hasten brain aging and memory deterioration, new research indicates.

Individuals consuming the highest amounts of artificial sweeteners showed a 62% accelerated rate of cognitive decline—equivalent to approximately 1.6 years of cognitive aging.

 

Younger Adults and Those With Diabetes Experience More Pronounced Effects

An eight-year observational study analyzing data from 12,772 Brazilian adults discovered that increased consumption of six artificial sweeteners and sugar alcohols—aspartame, saccharin, acesulfame K, erythritol, sorbitol, and xylitol—correlated with poorer cognitive outcomes.

The Food and Drug Administration (FDA) has authorized all these sweeteners for use in American food products.

The connection between artificial sweeteners and rapid cognitive decline proved particularly pronounced for individuals under 60 and those managing diabetes.

Individuals with diabetes frequently turn to artificial sweeteners for blood sugar management, and diabetes independently increases cognitive decline risk. While the association was more robust in people with diabetes, it appeared in those without the condition as well.

“Artificial sweeteners are not necessarily the safe, harmless alternatives to sugar that many of us assumed,” says Thomas M Holland, MD, MS, a physician scientist and assistant professor in the RUSH Institute for Healthy Aging.

 

The Potential Mechanism Behind Artificial Sweeteners’ Brain Impact

Since artificial sweeteners are processed ingredients, consider them a “marker” for ultra-processed foods, explained W. Taylor Kimberly, MD, PhD, a critical care neurologist at Mass General Brigham and an associate professor of neurology at Harvard Medical School.

Studies demonstrate that ultra-processed foods may contribute to cognitive deterioration even when someone adheres to brain-healthy eating patterns like the MIND or Mediterranean diets.

“This doesn’t mean you need to panic if you occasionally use diet products, but it’s another reminder that artificial sweeteners aren’t a ‘free pass.’ Moderation is key, and choosing whole foods over ultra-processed ones is a safer long-term bet,” says John “Wesley” McWhorter, DrPH, MS, RD, a Houston-based registered dietitian and spokesperson for the Academy of Nutrition and Dietetics.

According to Auriel A. Willette, PhD, MS, an associate professor of neurology at the Robert Wood Johnson Medical School of Rutgers University, artificial sweeteners may also alter the gut microbiome in ways that trigger glucose intolerance and systemic inflammation.

“Such changes that are linked to worse brain function, and there’s experimental and animal evidence showing sweeteners can promote oxidative stress and neuroinflammation,” Willette explained.

 

Sugar Doesn’t Offer Better Brain Health Protection

Artificial sweeteners aren’t the sole type of sweetener associated with cognitive decline. Studies have also linked simple sugars like fructose and sucrose—present in beverages, cereals, and desserts—with elevated dementia risk.

Switching from artificially sweetened diet soda to regular, sugar-laden soda doesn’t constitute a brain-healthy choice, Kimberly noted.

Excessive added sugar consumption can trigger additional health complications: cardiovascular disease, obesity, and type 2 diabetes.

“What’s probably most effective, rather than swapping one type of added sugar for another, is to swap the added sugar or artificial sweetener for unprocessed or minimally processed foods,” Kimberly said.