Research published in the journal Neurology indicates a potential association between the consumption of sugar substitutes and accelerated cognitive decline in Brazilian adults. The study, released in 2025, involved over 12,000 participants and suggests that while these sweeteners are often perceived as healthier alternatives to sugar, they may carry hidden risks.
The study tracked the cognitive health of 12,772 adults across Brazil for nearly eight years. Participants, averaging 52 years old and including a diverse demographic of 55% women and 43% Black or mixed-race individuals, reported their intake of various sugar substitutes through detailed questionnaires. The researchers specifically examined seven commonly used sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose.
Participants were categorized based on their consumption levels—low (20 milligrams per day), medium (66 mg), and high (191 mg). The findings revealed that those in the highest consumption category experienced a cognitive decline approximately 62% faster than those in the lowest category, equating to a difference of about 1.6 years of aging. The medium category showed a decline of 35%, or about 1.3 years.
Impact on Cognitive Function and Specific Areas Affected
The research further indicated that both the medium and high intake groups experienced significant drops in specific cognitive functions. Memory performance declined by 32% in the highest intake category, while verbal fluency declined by 110% and 173% in the middle and highest categories, respectively. Notably, this trend was more pronounced in participants under 60 years old and particularly impacted those with diabetes.
When analyzing individual sugar substitutes, the study found that increased consumption of six out of the seven examined—specifically aspartame, saccharin, acesulfame-K, erythritol, sorbitol, and xylitol—was linked to more rapid cognitive decline. Tagatose was the only sweetener that did not show this association.
Understanding the Implications of the Findings
While the study highlights a correlation between higher sugar substitute intake and cognitive decline, it does not establish a direct cause-and-effect relationship. According to Christine Byrne, MPH, RD, a dietitian and owner of Ruby Oak Nutrition, “this is yet another example that proves nutrition is complicated, and many food choices come with pros and cons.”
Researchers speculate that sugar substitutes may produce toxic metabolites during digestion that could lead to inflammation in the brain. Byrne emphasizes the importance of recognizing that correlations do not imply causation. “It’s impossible to know what the mechanism is,” she explains.
Previous studies have also noted similar associations between artificially sweetened products and cognitive issues, including memory impairment and increased dementia risk. Despite these findings, experts caution against completely eliminating sugar substitutes from diets, as they can provide benefits such as improved blood sugar control and reduced added sugar intake.
Byrne advises moderation, suggesting that individuals who consume multiple diet sodas or other artificially sweetened products daily might consider reducing their intake. “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,” she adds.
In summary, while the recent study sheds light on potential cognitive risks associated with sugar substitutes, it reinforces the need for a balanced view of dietary choices. As research continues, consumers are encouraged to make informed decisions regarding their sugar substitute consumption.
