A groundbreaking study published in the journal Neurology has raised concerns about the long-term effects of artificial sweeteners on cognitive health. The research, conducted by a team of Brazilian scientists, suggests that high consumption of certain low- and no-calorie sweeteners may be associated with faster cognitive decline, particularly in middle-aged adults and those with diabetes.
Key Findings of the Study
The study, led by Dr. Claudia Kimie Suemoto from the University of São Paulo, followed over 12,000 Brazilian adults with an average age of 52 for an average of eight years. Participants completed detailed dietary questionnaires at the beginning of the study, reporting their intake of various artificial sweeteners commonly found in ultra-processed foods such as flavored water, soda, energy drinks, yogurt, and low-calorie desserts.
The researchers focused on seven artificial sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose. They divided the participants into three groups based on their total consumption of these sweeteners. The lowest group consumed an average of 20 milligrams per day (mg/day), while the highest group consumed an average of 191 mg/day. For context, one can of diet soda sweetened with aspartame contains around 200 to 300 milligrams of the sweetener.
Cognitive Decline and Sweetener Consumption
Participants underwent cognitive tests at the start, midpoint, and end of the study to assess their memory, language, and thinking skills. The tests evaluated areas such as verbal fluency, working memory, word recall, and processing speed.
The results were striking. People who consumed the highest amounts of artificial sweeteners showed a 62% faster decline in overall thinking and memory skills compared to those who consumed the lowest amounts. This decline is equivalent to about 1.6 years of brain aging. Those in the middle group experienced a 35% faster decline, equivalent to about 1.3 years of aging.
Age and Diabetes: Significant Factors
The study revealed that the impact of artificial sweeteners on cognitive decline was more pronounced in certain groups. Specifically, adults under 60 years old and those with diabetes showed the fastest cognitive decline. This suggests that midlife dietary habits could have long-lasting consequences for brain health, even decades before the onset of cognitive symptoms.
Dr. Suemoto noted, “Cognitive performance peaks around the third decade of life, between 25 and 30 years old, and after that, there is a very slow, gradual decline in function. What our study shows is that sweetener consumption may accelerate this natural process, even in middle-aged adults.”
Potential Mechanisms
While the study did not establish a causal relationship between artificial sweeteners and cognitive decline, the researchers proposed several potential mechanisms. Animal studies suggest that aspartame can trigger inflammation in the brain, while sugar alcohols like erythritol and sorbitol may alter gut microbes and compromise the blood-brain barrier. However, these studies used very high doses of sweeteners, which are not typical of human consumption. Therefore, more research is needed to understand the effects of realistic doses in humans.
Not All Sweeteners Were Equal
Interestingly, not all sweeteners were associated with cognitive decline. Tagatose, a rare sugar, did not show any link to cognitive decline. The other six sweeteners—aspartame, saccharin, acesulfame-K, erythritol, sorbitol, and xylitol—were all significantly associated with faster cognitive decline, particularly in memory and verbal fluency.
Implications and Future Research
The findings of this study raise important questions about the safety and long-term health effects of artificial sweeteners. Dr. Suemoto emphasized the need for more research to confirm these findings and to explore the biological mechanisms underlying the observed associations. She also suggested that future studies should investigate whether other refined sugar alternatives, such as applesauce, honey, maple syrup, or coconut sugar, might be safer alternatives.
The International Sweeteners Association (ISA) responded to the study, noting that it is an observational study and cannot establish causation. The ISA also highlighted the safety of low- and no-calorie sweeteners, as confirmed by leading global health authorities.
Practical Advice
For individuals concerned about their cognitive health, Dr. Suemoto recommends moderation in the consumption of artificial sweeteners. “It is wise to limit consumption as much as possible, ideally avoiding daily use,” she advised. She also suggested focusing on a diet rich in whole, plant-based foods, which have been shown to promote brain health over time.
In Closing
This study adds to the growing body of research suggesting that artificial sweeteners may have unintended health consequences. While more research is needed to fully understand the mechanisms and long-term effects, the findings underscore the importance of a balanced and mindful approach to diet, especially for middle-aged adults and those with diabetes.