- Low-calorie sweeteners and sugar substitutes such as aspartame, saccharin, and xylitol have been used since the early 1900s.
- Past studies show there may be potential health risks to using sugar substitutes, including cognitive issues.
- A new study provides more evidence suggesting a correlation between sugar substitute use and cognitive decline.
Low-calorie sweeteners and sugar substitutes have been around for a long time. The first artificial sweetener, saccharin was first sold to consumers in the early 1900s.
Since the 1970s, the
Previous research has suggested there are some benefits to using sugar substitutes, including reducing blood sugar spikes in people with diabetes, and potentially protecting the teeth from cavities and decay.
However, there have also been a number of studies showing the potential health risks of sugar substitutes, such as a possible negative impact on the gut microbiome.
Furthermore, low-calorie sweeteners have been linked to a higher risk of certain health conditions, such as
A study published in Neurology, the medical journal of the American Academy of Neurology, in September 2025, now provides more evidence suggesting a correlation between sugar substitute use and cognitive decline.
For this study, researchers recruited 12,772 adults from Brazil, with a median age of 52. Participants completed questionnaires regarding their dietary habits, including what they drank. Scientists followed the participants for an average of eight years.
Scientists focused on the artificial sweeteners aspartame, saccharin, acesulfame-K, erythritol, xylitol,
“Previous studies had already shown that artificial sweeteners were linked to several health conditions, such as type 2 diabetes, cancer, cardiovascular disease, and depression, but their potential impact on cognition had not been investigated,” Claudia Kimie Suemoto, MD, PhD, formerly associate professor of geriatrics at the University of São Paulo in Brazil, now a professor specializing in longevity and aging neuroscience at UT Health San Antonio, told Medical News Today.
Suemoto, who is the lead author of this study, went on to explain the basis for the current research, noting that:
“In our own prior work with the
ELSA-Brasil study , we found that higher consumption of ultra-processed foods was associated with faster cognitive decline, and many sugar-free ultra-processed foods contain artificial sweeteners.”
At the study’s conclusion the researchers found that participants who had consumed the largest amount of sugar substitutes — an average of 191 milligrams a day (mg/day) — had a 62% faster decline in their overall thinking and memory skills, compared to those who consumed the least, on average 20 mg/day.
“A 62% faster decline means that people in the highest group of sweetener consumption experienced cognitive aging at a much quicker pace than expected, which could increase their risk of earlier impairment later in life,“ Suemoto explained.
“While our study cannot prove causation,“ she cautioned, “this magnitude of association raises concern that frequent sweetener consumption is not a harmless habit, and it underscores the need for more research and for people to be cautious with long-term use,” said the researcher.
Suemoto added that participants who consumed the largest amounts of artificial sweeteners showed declines in memory and overall thinking skills that were similar to what we would expect after 1.6 extra years of aging.
“This calculation is just a way to make the interpretation of the statistical results easier,” she detailed. “It does not mean someone instantly feels older, but rather that their brain function may be aging at a faster pace.“
“The significance is that even small accelerations in cognitive decline, when accumulated over years, can increase the risk of earlier or more severe impairment later in life,” Suemoto told us.
Additionally, researchers reported that in the study participant group that consumed the most artificial sweeteners, those under the age of 60 and those with diabetes had the fastest cognitive decline.
“One of the most surprising findings for me was that the association between low- and no-calorie sweetener consumption and cognitive decline was only significant among participants younger than 60 years old. I had expected the association to be more evident in older adults, since they are at higher risk of dementia and cognitive impairment. Instead, our results suggest that midlife exposure to sweeteners may be particularly harmful, which is important because midlife is a critical period for setting the trajectory of brain health.”
– Claudia Kimie Suemoto, MD, PhD
“Cognitive decline and dementia are thought to begin developing decades before symptoms become noticeable, so exposures during midlife may accelerate these processes and have long-term consequences,” she continued. “This emphasizes the importance of understanding dietary habits earlier in adulthood, when preventive strategies could have the greatest impact.”
“Our study suggests that high consumption of artificial sweeteners may be linked to faster cognitive decline. While more research is needed before making firm recommendations, it would be reasonable for people to reduce their intake as much as possible, ideally avoiding these products altogether,” the researcher advised.
MNT spoke with Kamal Wagle, MD, a geriatric specialist with Hackensack University Medical Center’s Center for Memory Loss and Brain Health in New Jersey, about this study.
Wagle, who was not involved in the study, commented that it is a noteworthy piece of research that adds to our understanding of how diet might affect long-term brain health.
Correlation not causation“While the finding that high consumption is linked to a faster decline is thought-provoking, it’s crucial to immediately highlight what the researchers themselves pointed out: this study shows a link, not a cause. It doesn’t prove that sweeteners are responsible for cognitive decline. It’s possible that other lifestyle factors associated with high sweetener consumption are at play. The fact that the link was stronger in people under 60 and those with diabetes is particularly interesting and tells us where we need to focus more attention.”
— Kamal Wagle, MD
“As a next step, I would like to see research that tries to understand the ‘why’ behind this link,” he continued. “This study was observational, so a more controlled study would be helpful to move closer to determining causation. Furthermore, research into the biological mechanisms is needed: how might these specific sweeteners affect brain cells or vascular health?”
“It would also be valuable to explore why this link was found in people under 60 but not older adults, and why the effect was more pronounced in those with diabetes,” Wagle added. “Finally, since tagatose was not associated with decline while the other six sweeteners were, investigating the differences between these compounds could provide crucial clues about what is actually happening at a biological level.”
Meanwhile, the Calorie Control Council, the international association representing the low- and reduced-calorie food and beverage industry, said it was important to point out that the study found a link and that correlation does not equal causation.
“This study has notable limitations, including reliance on self-reported dietary data collected only at baseline. While the authors admit finding no causal evidence, it risks misleading the millions with diabetes who rely on low/no-calorie sweeteners as recommended by the American Diabetes Association (ADA) and other global health experts,” Carla Saunders, president of the Calorie Control Council, said.
Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight, offered her top tips for those who may want to lower their consumption of low- and no-calorie artificial sweeteners.
“The new findings add to a pattern of concerns, not causations, that may be associated with intake of artificial sweeteners,” Richard commented. “The end result may signal caution and conscientiousness — not conclusivity — and it reinforces my usual guidance to individuals and families to prioritize whole foods and savor Mother Nature’s sweeteners sparingly when necessary.”
Richard advised that, in addition to meeting with a registered dietitian nutritionist (RDN) to assess individual needs, concerns, and dietary patterns, some general tips to minimize the use of artificial sweeteners in general include:
- conduct a “sweetener audit” by scaning the labels of foods you regularly consume for common sweeteners such as aspartame, sucralose, saccharin, acesulfame-K,
neotame ,advantame , and erythritol/xylitol to track daily “sweet hits” — such as drinks, bars, yogurts, and gums — for a week - taper intake by decreasing, by 25% or 50%, the amount of sweetener you use over 2 to 4 weeks to none, or to naturally flavored seltzer, unsweetened tea, water with citrus, berries, herbs, or a combination
- checking your tastebuds with an “apple test” — checking how an apple tastes to you you on a scale of 1-10, with 10 being very sweet; if you find that you are not as sensitive to the sweetness of fruit, over time, you can “retrain” taste buds
- swap out sweetener with flavor by using vanilla, cinnamon, cocoa, citrus zest, ginger, mint, or cardamom to boost satisfaction in coffee, yogurt, and oatmeal
- finally, use a touch of “Mother Nature’s sugar” by trying honey, maple syrup, fruit, pure sugarcane, agave, or monk fruit to sweeten beverages, baked goods, dressings, sauces or desserts.
“Don’t fear, but do add flavor and see how you can filter out the ‘hyper-sweet’ and synthetic additives in the diet for a healthier body and brain,” Richard suggested.