A small randomized crossover trial found that eating unsalted, skin-roasted peanuts daily changed an MRI-based measure of insulin responsiveness in memory-related brain regions. The finding is intriguing, but it does not show that peanuts prevent cognitive decline or Alzheimer’s disease.
What changed
Thirty-one healthy adults ages 60–75 consumed 60 grams of peanuts per day for 16 weeks and completed a no-peanut control period, separated by an eight-week washout. After intranasal insulin, researchers measured regional cerebral blood flow using arterial-spin-labeling MRI. Compared with control, the peanut period altered the insulin-related blood-flow response in one right-hemisphere cluster that included the hippocampus, parahippocampal gyrus, thalamus and posterior cingulate. The study did not find effects on liver fat or standard metabolic blood markers.
How strong is the evidence?
This was peer-reviewed human randomized crossover evidence, so each participant served as their own comparison. The controlled feeding period and brain imaging strengthen the experiment. However, regional blood-flow response to insulin is a surrogate marker—not a diagnosis, symptom or clinical outcome.
What remains uncertain
The sample was small and limited to generally healthy older adults. The study did not test dementia incidence or establish that the imaging change improves everyday cognition. It also cannot identify which peanut component caused the response. The Peanut Institute Foundation funded the work; researchers reported that the funder had no role in design, analysis or writing.
Why it matters
The result supports larger independent trials connecting brain insulin signaling with meaningful cognitive outcomes. For now, it is evidence of a biological signal—not a reason to treat peanuts as an Alzheimer’s therapy.
Sources
Original study in Food & Function, published September 30, 2026; research report, October 10, 2026.
Illustrative stock photograph by Rafael Rodrigues on Unsplash; it does not depict the study participants, intervention packets or results.
