Older adults who ate two handfuls of peanuts a day for 16 weeks showed changes in the brain regions that matter most for memory
Peanuts are one of the cheapest and most common snacks in the world. Researchers at Maastricht University in the Netherlands wanted to know whether that reaches the aging brain. They gave 31 healthy adults aged 60 to 75 about 60 grams of unsalted, skin-roasted peanuts every day for 16 weeks, roughly two small handfuls, and compared that with 16 weeks of eating no peanuts. Each person went through both periods, in random order, with brain scans along the way.
During the peanut period, blood flow to the brain rose by 3.6% overall, and by 4.5% in the brain’s gray matter. Participants also remembered 5.8% more words on a delayed memory test, about 1.4 extra words, and their systolic blood pressure fell by about 5 points.
A newly published follow-up analysis from the same trial found something more specific. After the peanut period, regions of the brain involved in memory became more responsive to insulin, a hormone that also acts in the brain and whose effects tend to weaken with age. Poor insulin responsiveness in the brain has been linked to Alzheimer’s disease.
“Our study found that daily peanut consumption beneficially affected insulin responsiveness in memory-related brain regions in older adults,” the researchers said.
The team chose skin-roasted peanuts on purpose. The thin red skins contain polyphenols, plant compounds with antioxidant effects, and peanuts also provide L-arginine, which the body uses to make nitric oxide, a molecule that helps blood vessels relax.
The evidence is not all in one direction. A separate 12-week trial published this year gave peanuts and peanut butter to 30 overweight older adults with memory complaints and heart risk factors, and found no significant change in thinking or brain activation. Differences in health, dose and trial length may explain the gap, but it is a reminder that small trials can disagree.
The second finding is about blood pressure. The roughly 5-point drop in systolic pressure is in the range seen with some dietary changes recommended for heart health, and blood vessels that serve the heart also serve the brain.
For anyone who likes peanuts, the findings are a reasonable reason to keep them in the diet, as long as they are unsalted and eaten in place of less healthy snacks rather than on top of them. Sixty grams of peanuts contains roughly 350 calories. Healthy eating patterns tend to show benefits across the board, as a study of 10 diets and biological aging found, and small daily habits can matter, as with tea and heart health.
There are limits to what this shows. With 31 participants, the trial was small and lasted 16 weeks, so it cannot show whether peanuts protect against dementia. Participants were healthy, and the results may not apply to people with memory problems. The memory gain was modest. Nut-industry funding is common in research of this kind, and the papers’ funding statements are worth checking.
Source
Kerkhof L, et al. “Daily consumption of unsalted, skin-roasted peanuts beneficially affects regional brain insulin responsiveness in older adults: results of a longer-term randomized controlled trial.” Food & Function, 2026.
DOI: 10.1039/D6FO03208G
Also cited
Chiriac G, Barnes SR, et al. “Effects of peanut consumption on task-related brain activation, cognition and neuroinflammation in older adults with memory complaints: a randomized controlled trial.” Frontiers in Nutrition, 2026.
DOI: 10.3389/fnut.2026.1817518
