REVIEW OF: Bhave VM et al, Neurology 2024;102(11):e209432

STUDY TYPE: Prospective cohort study

We tell patients to “eat healthy,” but what does that actually mean? This large prospective study from the REGARDS cohort suggests that how food is processed matters for the brain, over and above adherence to Mediterranean, DASH, or MIND diets. More than 21,000 Black and White US adults aged 45 and older completed baseline dietary assessments, with follow-up averaging about 11 years for both cognitive and stroke outcomes.

Using the NOVA classification system, the investigators found that each 10% increase in ultra-processed food (UPF) intake, such as packaged snacks, chicken nuggets, and sugary cereals, was associated with 16% higher risk of cognitive impairment and 8% higher stroke risk. Each 10% increase in unprocessed or minimally processed foods reduced those risks by 12% and 9%, respectively. Both associations held after adjusting for established dietary quality scores and the usual cardiovascular confounders. Stroke risk from UPFs was significantly more pronounced in Black participants than in White participants. This was a pre-specified focus of the REGARDS cohort, which oversampled Black adults and residents of the Stroke Belt.

CARLAT TAKE

These are observational data, so causality isn’t proven. However, the effect sizes are clinically meaningful, and the associations survived adjustment for the best dietary benchmarks available. The practical takeaway is a shift in framing. Rather than advising patients to eat a Mediterranean diet, try something more concrete. Cut packaged and reconstituted foods and replace them with fresh produce, whole grains, legumes, and plain dairy. Because Black patients face social hardships that can exacerbate cardiovascular risk factors, the stroke signal warrants proactive conversation.