Although insulin is best known for regulating blood sugar, it also plays a vital role in the brain, supporting nerve cell growth, survival and communication, and underpinning memory and other cognitive abilities. Healthy insulin signalling may also help protect against processes linked to Alzheimer’s disease.
Following daily peanut consumption for 16 weeks, researchers observed improved insulin responsiveness in a group of brain regions in the right hemisphere. These included portions of the lingual gyrus, hippocampus, parahippocampal gyrus and posterior cingulate gyrus, all of which contribute to memory-related processes.
“The hormone insulin plays an important role in the brain, where it supports memory and other cognitive processes. As people age, the brain may become less responsive to insulin, which has been linked to age-related cognitive decline,” says Dr. Peter Joris, the study’s senior author and an associate professor in the Department of Nutrition and Movement Sciences, NUTRIM, Maastricht University Medical Center. “Our study found that daily peanut consumption beneficially affected insulin responsiveness in memory-related brain regions in older adults. These findings suggest that enhanced regional brain insulin responsiveness may contribute to the cognitive benefits of unsalted, skin-roasted peanut intake.”
The study involved 31 healthy adults aged 60 to 75 who, during the peanut phase, consumed 60 grams (about two servings) of peanuts each day for 16 weeks. Researchers used a randomized, controlled crossover design, allowing comparison of peanut consumption with a control period in which peanuts were avoided.
The new findings build on Joris’s earlier research published in 2025, which reported that peanut consumption for 16 weeks increased overall cerebral blood flow by 3.6% and improved verbal memory performance by 5.8%.
Cerebral blood flow measures how much blood circulates through the brain, delivering oxygen and nutrients to support function. These earlier results appeared in Clinical Nutrition.
To examine changes in brain function, researchers used arterial spin labelling magnetic resonance imaging (ASL-MRI), a technique that measures blood flow in different brain regions. Insulin responsiveness was assessed by tracking changes in regional cerebral blood flow after intranasal insulin administration.
The team also utilised abdominal MRI scans to measure fat accumulation in the liver (intrahepatic lipid, IHL content) and evaluated cognitive abilities using the Cambridge Neuropsychological Test Automated Battery (CANTAB).
Researchers believe several components of peanuts may contribute to the observed brain health benefits, rather than any single nutrient being responsible. “Multiple nutrients present in peanuts, including unsaturated fats, dietary fibre, vitamins and minerals and bioactive phytochemicals, could potentially contribute to the observed brain benefits,” says Joris. “Peanuts are also a good source of plant-based protein and are especially rich in L-arginine. L-arginine is a key precursor of nitric oxide (NO), which has been reported to facilitate learning and memory performance.”
To ensure consistency, researchers supplied participants with premeasured packets of skin-roasted peanuts throughout the peanut intervention period. Participants were advised to eat their peanuts in the morning or afternoon and could consume the entire portion at once, divide it into smaller amounts, or incorporate them into meals. During the control phase, peanuts were avoided, and after 16 weeks, participants crossed over to the opposite condition.
The study was led by Associate Professor Dr Peter J. Joris and conducted by PhD candidate Lucia Kerkhof of the Department of Nutrition and Movement Sciences at Maastricht University Medical Center. Funding was provided by The Peanut Institute Foundation, which had no involvement in designing or conducting the study, analysing or interpreting the results, or preparing the manuscript.
