7 sugar substitutes linked to 62% faster decline in thinking, memory skills

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.

Now, a new study recently published in Neurology, the medical journal of the American Academy of Neurology, provides more evidence suggesting a correlation between sugar substitute use and cognitive decline.

For this study, researchers recruited more than 12,000 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, sorbitol, and tagatose, in their study.

“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, associate professor of geriatrics at the University of São Paulo in Brazil and lead author of this study told Medical News Today.

“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,” she said.

At the study’s conclusion, researchers found that study participants who consumed the largest amount of sugar substitutes — an average of 191 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. While our study cannot prove causation, 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.”

— Claudia Kimie Suemoto, MD, PhD

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.”

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,” Suemoto said. “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.”

“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.”

— Claudia Kimie Suemoto, MD, PhD

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.”

For readers who may want to lower their consumption of low- and no-calorie artificial sweeteners, we asked Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight, for her top tips.

“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 said, in addition to meeting with a registered dietitian nutritionist (RDN) to assess your individual needs, concerns, and dietary patterns, some general tips to minimize the use of artificial sweeteners in general include:

• Conduct a Sweetener Audit: Scan labels of foods you regularly consume for common sweeteners such as aspartame, sucralose, saccharin, acesulfame-K, neotame, advantame, and erythritol/xylitol to track your daily “sweet hits” (drinks, bars, yogurts, and gums) for a week.
• Taper Intake: Try decreasing, by 25% or 50%, the amount of sweetener you use over two to four weeks to none, or to naturally flavored seltzer, unsweet tea, or water with citrus, berries, herbs, or a combination.
• Check Your Tastebuds With an Apple Test: On a scale of 1-10, with 10 being very sweet, how does an apple rate? It may indicate that you’ve frequently chosen sweetened foods often and are not as sensitive to naturally sweet food such as fruit. Over time, taste buds can be “retrained” and the “natural sweet” radar restored.
• Swap Out Sweetener With Flavor: Use vanilla, cinnamon, cocoa, citrus zest, ginger, mint, or cardamom to boost satisfaction in coffee, yogurt, and oatmeal.
• Use a Touch of Mother Nature’s Sugar: Try honey, maple syrup, fruit, pure sugarcane, agave, or monk fruit to sweeten beverages, baked goods, dressings, sauces or desserts — a little goes a long way.

“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 added.