You probably know peanuts as a cheap, filling snack. Most of us keep a bag in the cupboard and barely think about it. Few would guess a daily handful could do anything measurable to the aging brain.
Researchers at Maastricht University have now reported exactly that. In a small randomized trial published in Food & Function, 31 healthy adults aged 60 to 75 ate 60 grams of unsalted, skin-roasted peanuts every day for 16 weeks.
After the peanut phase, memory-related areas on the right side of their brains responded more strongly to insulin. The affected cluster included the hippocampus, a region central to memory, along with nearby areas on either side of it.
Each participant swapped between a peanut period and a no-peanut period in random order, with an eight-week break in between. That design lets each person serve as their own comparison, which is a stronger way to test a dietary effect in a small group.
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Why insulin matters for the aging brain
Insulin is best known for moving sugar out of the blood. In the brain, it has a second job. It helps nerve cells grow and communicate, and those processes shape how we form and keep memories.
As people age, the brain can start to ignore insulin's signal. Lower brain insulin responsiveness has been tied to cognitive decline and to Alzheimer's disease in earlier research. That is the gap the Maastricht team wanted to probe with a simple food.
"The hormone insulin plays an important role in the brain, where it supports memory and other cognitive processes," study author Peter Joris of Maastricht University said about the findings.
What the same trial already showed about memory
The current paper is the second report from this trial. An earlier analysis in Clinical Nutrition, published in November 2025, looked at blood flow and memory in the same 31 participants.
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In that report, 16 weeks of daily peanuts raised overall brain blood flow by 3.6 percent. Verbal memory on a delayed recall task was 5.8 percent better during the peanut period than during the control period.
Blood pressure also edged down. Systolic blood pressure fell by about 5 mmHg and pulse pressure by about 4 mmHg while participants were eating peanuts.
What the study cannot answer yet
The sample is small. Only 31 people took part, all healthy and between 60 and 75. The trial does not show whether peanuts prevent dementia, and it did not compare peanuts with other nuts or snacks.
The researchers point to the mix of unsaturated fats, fiber, vitamins, minerals and plant compounds in peanuts as a plausible reason for the effect. The trial was not designed to pin the benefit on any single ingredient.
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The work was funded by The Peanut Institute Foundation. The authors state the funder had no role in study design, analysis or interpretation.
The dose used in the trial was 60 grams a day of unsalted, skin-roasted peanuts, about two small handfuls, taken for 16 weeks before the brain measures changed.
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This article is made and published by Aksel Kryhlmand, who may have used AI in the preparation.