If you’ve ever swapped sugar for something “lighter” in your tea or morning yoghurt, you’re not alone. Sweeteners are in nearly everything these days, from drinks to protein bars, and most of us assume they’re the smarter choice.
But new research suggests that some of these sugar substitutes might not be as harmless as they seem - and the findings are giving scientists plenty to think about.
This article is intended for general informational purposes only. It’s not medical advice, and individual reactions to sweeteners can vary. If you’re concerned about your diet or cognitive health, speak with a qualified healthcare professional before making changes.
What The New Study Actually Found
A new long-term study published in Neurology, the journal of the American Academy of Neurology, found that people who regularly consumed low or no-calorie sweeteners such as aspartame, saccharin, and erythritol experienced faster declines in memory and thinking skills compared with those who ate less. Researchers followed more than ten thousand adults for about eight years and noticed the link was most noticeable in participants under sixty.
It’s important to note this was an observational study, meaning it shows an association but not direct cause and effect.
Which Sweeteners Were Tracked
Seven sweeteners were assessed via diet questionnaires: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose.
In analyses of individual sweeteners, aspartame, saccharin, acesulfame-K, erythritol, sorbitol, and xylitol were associated with faster decline; tagatose was not linked to decline in this dataset. Not all sweeteners (for example, sucralose) were evaluated.
How Big Might The Effect Be?
These figures were adjusted for factors such as age, education, physical activity, and overall diet quality to help isolate the relationship with sweetener intake. The researchers also noted that the link appeared strongest among participants with type 2 diabetes, suggesting that metabolic health may play a role in how these sweeteners affect the brain.
Association Versus Causation
Because diets were self-reported and many lifestyle factors co-vary, residual confounding cannot be ruled out; the authors adjusted for numerous variables, but the design cannot prove that sweeteners cause cognitive decline.
How This Compares With Earlier Research
Other cohort studies, such as those published in Stroke and Alzheimer’s & Dementia, have reported similar associations between diet drink consumption and poorer brain outcomes. Experimental studies in animals have also hinted at possible effects of aspartame and other sweeteners on neurotransmitters and oxidative stress.
However, human data remain limited, and scientists continue to emphasise that more controlled trials are needed to confirm any direct impact.
