04/09/2025
There’s growing evidence of an association—but not proof of causation—between high intake of artificial sweeteners (the kinds used in Diet Coke and similar drinks) and faster decline in some aspects of cognition.
Here’s the best current read:
• A large new cohort study (12,772 Brazilian adults, 8-year follow-up) just published in Neurology found that people with the highest intake of low-/no-calorie sweeteners (aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol) had a ~62% faster decline in memory, verbal fluency and overall cognition than those with the lowest intake. The signal was strongest in adults under 60 and in people with diabetes. (Observational study → can’t prove cause.)
• Earlier observational work (Framingham Offspring, 2,888 adults) linked diet-soda intake with a higher risk of stroke and dementia—again, association only.
• Small human experiments suggest short-term brain/metabolic effects. A randomized trial (n=39, 6 weeks) reported that sucralose supplementation worsened performance on memory/executive-function tests; another trial showed altered brain and insulin responses when sucralose was consumed with carbohydrate. (These are small/short studies, so treat as preliminary.)
What about Diet Coke specifically?
• Diet Coke is typically sweetened with aspartame (sometimes with a bit of acesulfame-K; formulas vary by market—check your can’s label).
• Regulators still consider aspartame safe within the acceptable daily intake (ADI): WHO/JECFA and the FDA have kept the ADI at ~40–50 mg/kg/day. WHO notes a typical diet soft drink has ~200–300 mg aspartame; a 70-kg adult would need >9–14 cans/day to exceed the ADI (not a recommendation—just context).
How to use this info pragmatically
• If brain health is a priority, it’s sensible to avoid making diet sodas a daily habit, especially if you’re
People consuming the high levels of certain artificial sweeteners — about 1 teaspoon daily — saw their cognitive abilities decline by 1.5 years, a new study found.
