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The Hidden Brain Cost Of “Healthy” Sweeteners, Research Finds

Ava Durgin
Author:
October 06, 2025
Ava Durgin
Assistant Health Editor
Looking Down On Sun Lit Baking Ingredients
Image by Lucas Saugen / Stocksy
October 06, 2025

For years, low-calorie sweeteners like aspartame, saccharin, and xylitol have been marketed as a healthier swap for sugar—one that lets you keep your favorite treats without the “empty calories.” They’ve made their way into diet sodas, sugar-free gums, and many of the “better-for-you” snacks.

But new research suggests there’s a hidden cost: your brain.

Sweeteners & brain health

The study tracked more than 12,700 adults for up to 11 years, during which they completed repeated dietary surveys and a battery of six cognitive tests measuring memory, attention, verbal fluency, and overall cognitive performance.

Researchers specifically examined consumption of seven common low- or no-calorie sweeteners:

  • Aspartame
  • Saccharin
  • Acesulfame-K
  • Erythritol
  • Xylitol
  • Sorbitol
  • Tagatose

The impact of just one soda

Researchers compared people who consumed the highest amounts (~191 mg/day, approximately the amount in one diet soda) to those who consumed the least (~20 mg/day). Here’s what they found:

  • 62% faster decline: Participants who consumed the most sweeteners had a 62% faster decline in memory, attention, and verbal fluency compared to low consumers.
  • Younger brains were more affected: The association was strongest in adults under 60, suggesting younger brains may be more sensitive to sweetener-related brain changes.
  • Not just one culprit: Several sweeteners—including aspartame, saccharin, acesulfame-K, erythritol, xylitol, and sorbitol—were linked to faster decline.

What this means for your daily habits

This doesn’t mean you need to panic if you’ve been sprinkling sweetener into your coffee or sipping a diet soda here and there. The study doesn’t suggest that small or occasional use causes harm. Instead, the risks were seen in people consuming sweeteners regularly at higher levels, closer to one or more servings a day.

Here are some practical ways to use this research in your own life:

  • Cut back on the daily diet soda. An occasional can isn’t likely to cause harm, but if it’s part of your everyday routine, try swapping in sparkling water or kombucha.
  • Read labels carefully. Many “sugar-free” products—like snack bars, flavored yogurts, and condiments—pack in multiple sweeteners that add up quickly.
  • Opt for real, nutrient-rich sweetness. Whole fruits, a drizzle of honey, or a touch of maple syrup deliver natural flavor plus antioxidants and polyphenols.
  • Think big picture. Brain health depends more on your overall diet than on one ingredient. Prioritizing fiber, healthy fats, and quality protein will serve you better than micromanaging every sweetener.

The takeaway

This study adds to a growing body of evidence that low-calorie sweeteners may not be the harmless sugar swap they’re often marketed to be. They may come at the expense of long-term brain health.

Don’t fear every packet of sweetener or piece of sugar-free gum. Instead, it’s about recognizing patterns: if artificial sweeteners are a daily habit, it may be worth scaling back and leaning more on whole, nutrient-rich foods to satisfy your sweet tooth.