The Western diet is linked to faster memory loss
STUDY: Wöbbeking-Sánchez M et al, Nutrients 2026;18:1361
STUDY TYPE: Systematic review
FUNDING: Facultad de Psicología, Universidad Anáhuac México; Dirección de Investigación, Universidad Anáhuac México
Background
Ultraprocessed foods are industrially manufactured products that bear little resemblance to their nutrient origins. Canned tomatoes, sliced bread, and butter are minimally processed, but ultraprocessed means packaged snacks, fast food, sugary drinks, and frozen meals. Even healthy-looking stuff like 100% whole grain chips.
They are linked to obesity, metabolic disease, and cardiovascular disease. This review looks at their cognitive toll.
The Study
- 16 studies that examined ultraprocessed food intake and cognitive performance in adults 18 and older.
- Two randomized trials; the rest prospective cohort studies and cross-sectional analyses.
- Most used food questionnaires; about half used the NOVA food classification system to define ultraprocessed foods.
Results
81% of studies found worse cognitive outcomes with higher ultraprocessed food consumption: impaired memory, executive function, and global cognition.
In middle-aged adults, getting more than 19% of daily calories from ultraprocessed foods was linked to a 28% faster rate of global cognitive decline and a 25% faster rate of executive function decline. Older adults showed increased risk of mild cognitive impairment and dementia.
Results in younger adults were mixed. One observational study found no link between ultraprocessed food intake and executive function problems; a small randomized crossover trial found that young adults on an ultraprocessed food diet showed weaker inhibitory control.
The three studies that found no association were all cross-sectional, which may not detect the cumulative effects of long-term dietary exposure.
How Do They Harm?
Gut microbiome disruption, neuroinflammation, and deficits in key micronutrients such as magnesium, zinc, and vitamins C, D, and B12. They are linked to reduced brain volume in the amygdala and frontal cortex. Trans fats alter the composition of brain cell membranes, impairing communication between neurons.
Limitations
Most studies were observational, so cause cannot be established. However, animal studies do show causation, as did a crossover study discussed above. For people with metabolic syndrome, we have randomized trials showing cognition improves when ultraprocessed foods are cut (these were not a part of this review).
Practice Implications
- Limit processed foods to three small servings per week (or less). That’s the guidance from the diet for depression, which also helps cognition.
- The OpenFoodFacts app scans grocery items and rates them on the Nova processing system.
— Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
