Adults who consumed the most low- and no-calorie sweeteners showed cognitive decline 62% faster than those who consumed the least, according to a study published in the medical journal Neurology. Six sweeteners were tied to the effect, including aspartame, saccharin, acesulfame-K, erythritol, xylitol, and sorbitol.
Tagatose was the only one of the seven examined that was not linked to faster decline. The gap works out to roughly 1.6 additional years of brain aging over the eight-year follow-up.
Participants in the middle consumption group fared better but still declined about 35% faster than low consumers, an effect the researchers compared to 1.3 extra years of aging.
Researchers at the University of São Paulo followed 12,772 Brazilian adults with an average age of 52, tracking their diets and running cognitive tests across three waves between 2008 and 2019, the American Academy of Neurology reported.
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"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 lead author Claudia Kimie Suemoto, MD, PhD.
There is an important caveat. The study is observational, meaning it shows a pattern, not a cause.
Sweetener consumption can travel with other habits, such as diet quality, weight, or underlying health conditions, that could contribute to the decline. The team also noted that dietary intake was self-reported.
Why age and diabetes mattered
The link was clearest in adults under 60. In people over 60, the researchers found no significant association. Effects were also stronger among participants with diabetes, a group more likely to use sugar substitutes.
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Suemoto has called the age pattern one of the more surprising results, since she had expected to see stronger effects in older adults, according to Medical News Today.
Where these sweeteners hide on the label
Aspartame turns up in many diet sodas, chewing gum, and tabletop sweetener packets. Saccharin, one of the oldest sugar substitutes, appears in packets and processed foods and drinks.
Sugar alcohols like xylitol, sorbitol, and erythritol are common in sugar-free gum, mints, low-carb baked goods, and "keto" desserts. Acesulfame-K is often blended with other sweeteners in diet drinks and flavored waters.
None of these ingredients are being pulled from the market, and each is approved by US regulators as a food additive. Still, if your day quietly runs on zero-sugar drinks and sugar-free treats, the new research is a nudge to notice how much you are really consuming and to raise it with your doctor, especially if you have diabetes.
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