Peanuts may improve regional brain insulin response

A randomized crossover trial found changes in insulin-induced cerebral blood flow following 16 weeks of daily peanut consumption, although the connection to improved memory remains unclear.

By
Andrea Surnit
October 16, 2026
4 min

MDSpire News

Overview

In a randomized, single-blind crossover trial of 31 adults aged 60–75 years, 60 g of unsalted, skin-roasted peanuts daily for 16 weeks was associated with a lower insulin-induced cerebral blood flow response in one right-hemisphere cluster involving memory-related regions. No significant differences were found in global or broader brain measures, and the regional change was not significantly associated with previously reported improvement in verbal recognition memory.

Background

Brain insulin responsiveness is studied in relation to cognitive processes, including memory, and can be assessed indirectly through cerebral blood flow responses after intranasal insulin. The trial examined whether sustained peanut consumption affected this response in older adults, alongside metabolic and inflammatory measures. Its findings concern a regional imaging outcome and do not establish direct changes in neuronal insulin signaling. Related research has examined intranasal insulin delivery to the brain and insulin-related hippocampal responses, but those studies address different questions.

Data Highlights

Measure	Finding
Participants and design	31 adults aged 60–75 years completed a randomized, single-blind crossover trial; mean age 67 years, 15 women. Each completed 16 weeks of 60 g/day unsalted, skin-roasted peanuts and a 16-week control period, separated by an 8-week washout.
Regional insulin-induced cerebral blood flow	One right-hemisphere cluster showed a significant reduction after peanut consumption versus control: mean difference −5.4 mL/100 g brain tissue/min; cluster volume 552 mm³. It included portions of the lingual gyrus, hippocampus, parahippocampal gyrus, thalamus, and posterior cingulate gyrus.
Broader brain measures	No significant differences in insulin-induced cerebral blood flow responses at global, gray matter, cortical, or subcortical levels.
Memory association	Regional response changes were not significantly associated with previously reported improvements in verbal recognition memory in the same study population.
Metabolic and inflammatory measures	No significant effects on liver fat (5.3% after peanuts vs 5.0% during control), fasting glucose, insulin, HOMA-IR, total cholesterol, LDL cholesterol, HDL cholesterol, or high-sensitivity C-reactive protein. Triglycerides were lower after 8 weeks (mean difference −0.20 mmol/L), but this difference was not evident at week 16.
Adherence and safety	Median adherence was 100%. One participant withdrew because of gastrointestinal discomfort; no study-related serious adverse events were reported.

Key Findings

Participants received 60 g of unsalted, skin-roasted peanuts daily for 16 weeks and completed a control period without nuts, with an 8-week washout.
Whole-brain analysis identified one right-sided cluster with a statistically significant reduction in insulin-induced cerebral blood flow after the peanut intervention compared with control.
The cluster included portions of several regions associated with memory-related processes; the highest average localization probabilities were in the lingual gyrus (20%), hippocampus (14%), and parahippocampal gyrus (11%).
No significant differences were detected in global, gray matter, cortical, or subcortical cerebral blood flow responses, and regional changes were not significantly associated with verbal recognition memory improvement previously reported in this cohort.
Fasting glucose, insulin, HOMA-IR, liver fat, cholesterol measures, and high-sensitivity C-reactive protein did not differ significantly between intervention and control periods. The triglyceride difference observed at week 8 was no longer evident at week 16.
The authors noted that cerebral blood flow responses are an indirect measure of insulin-related neuronal activity; the small sample and absence of an energy- and macronutrient-matched control limit interpretation.

Clinical Implications

The study reports a region-specific imaging change, not a demonstrated improvement in cognition or direct evidence of altered neuronal insulin signaling. The authors state that the relationship between the regional response and previously reported verbal recognition memory improvement could not be determined; the small sample and lack of an energy- and macronutrient-matched control are relevant limitations.

Conclusion

Sixteen weeks of daily peanut consumption was associated with a lower insulin-induced cerebral blood flow response in a right-hemisphere cluster involving memory-related regions, without significant changes in broader brain measures or a significant association with verbal recognition memory. The findings do not establish the mechanism or cognitive significance of this regional response.