Could Artificial Sweeteners Affect Brain Health?

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Artificial sweeteners are everywhere — diet sodas, flavored waters, low-calorie desserts, protein shakes even some yogurts. Many people turn to these low- and no-calorie sweeteners (LNCSs) as a way to cut sugar and calories, especially if they are trying to manage weight, blood sugar or other health concerns. But a new study published in Neurology, the medical journal of the American Academy of Neurology, suggests that these sugar substitutes may not be as harmless as they seem when it comes to long-term brain health.

“Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar; however, our findings suggest certain sweeteners may have negative effects on brain health over time,” said study investigator Claudia Kimie Suemoto, M.D., Ph.D., of the University of São Paulo in Brazil.

The Study at a Glance

A team of investigators from Brazil followed 12,772 adults, with an average age of 52 years, for about eight years. Participants were part of the Brazilian Longitudinal Study of Adult Health, which tracks the health of thousands of civil servants over time. Importantly, this study involved a large, diverse group of people and tracked them for nearly a decade.

At the beginning of the study, participants filled out detailed food questionnaires that captured what they ate and drank over the previous year. From this, researchers calculated how much of seven common artificial sweeteners people consumed: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. These sweeteners are commonly found in ultraprocessed foods such as diet sodas, flavored water, energy drinks, “sugar-free” desserts, gum and some yogurts.

Researchers then divided participants into three groups based on their intake, with the low-intake group consuming about 20 mg/day (roughly less than a sip of diet soda) and the high-intake group consuming about 191 mg/day on average — the equivalent of one can of diet soda (for aspartame).

Participants also underwent cognitive testing at three points during the study — at the start, in the middle and at the end. These tests measured skills like memory, attention, processing speed, verbal fluency and working memory.

What They Found

Over the eight years, people who consumed the highest levels of artificial sweeteners showed a 62% faster decline in overall memory and thinking abilities compared with those who consumed the least. This decline was equivalent to about 1.6 years of extra aging.

Those in the middle group also showed a 35% faster decline, equal to about 1.3 years of aging.

The effect was especially pronounced in people under the age of 60. For younger adults, high consumption of sweeteners was linked to faster decline in verbal fluency and global cognition. For people over 60, the link was not as clear.

Another key finding: The connection between sweeteners and brain health appeared stronger in people with diabetes. Since many people with diabetes rely on sugar substitutes to manage their condition, this is an important consideration.

When looking at individual sweeteners, the study found that aspartame, saccharin, acesulfame-K, erythritol, xylitol and sorbitol were associated with faster decline in thinking and memory. The only sweetener with no observed effect was tagatose.

“While we found links to cognitive decline for middle-aged people both with and without diabetes, people with diabetes are more likely to use artificial sweeteners as sugar substitutes,” said Suemoto. “More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, may be effective alternatives.”