Research suggests that incorporating unsalted, skin-on roasted peanuts into the diet daily could enhance memory and cerebral blood circulation in older individuals.

In the study, participants who consumed 60 grams of peanuts, equating to roughly two handfuls, each day over a period of 16 weeks, demonstrated a 5.8 percent boost in verbal memory. They excelled in tasks requiring them to remember words from a list after a delay.

The positive effects are believed to come from L-arginine, an amino acid present in peanuts that enhances cerebral blood flow, along with bioactive compounds in the peanut skins that offer protection to brain cells.

When blood flow improves, the brain receives increased oxygen and nutrients, thereby bolstering memory and cognitive abilities.

Imaging studies showed that overall cerebral blood flow went up by 3.6 percent, with an even greater increase of 4.5 percent specifically in the brain’s gray matter.

Blood flow in key regions associated with memory and language also improved, rising 6.6 percent in the frontal lobes and 4.9 percent in the temporal lobes.

Peter J Joris, from Maastricht University in the Netherlands, said: ‘Adequate blood flow in the brain is important for the delivery of oxygen and nutrients to the brain cells. 

‘Without enough oxygen and nutrients, the highly metabolically active brain cannot function properly, and key functions like memory can be affected.’

Participants who consumed 60 grams, about two handfuls, of peanuts each day for 16 weeks showed a 5.8 percent improvement in verbal memory, performing better at recalling words from a list after a delay

The study, conducted in two phases, involved 31 healthy adults, aged 65 to 75, who had no history of cardiovascular disease, diabetes, or peanut allergies and were not current smokers, PsyPost reported.

During the intervention phase, participants ate 60 grams of unsalted, skin-roasted peanuts daily for 16 weeks. 

In the control phase, they avoided peanuts and other nut-based products for 16 weeks, following an eight-week break between phases. 

This crossover design allowed each person to act as their own baseline, directly comparing the effects of peanut consumption with no peanuts.

Researchers measured brain blood flow using a non-invasive MRI technique and tested memory, thinking speed, and problem-solving skills with computerized cognitive tests. Blood pressure and diet were also tracked through questionnaires.

‘We were intrigued to see improvements not only in specific brain regions but across the whole brain,’ Joris said. 

‘That indicates a more widespread effect on vascular function than we observed in earlier studies.’

Along with changes in blood flow, participants performed better on memory tasks, recalling more words from a list they had seen 20 minutes earlier compared with the control period.

Average brain blood flow maps after the study showed (A) participants who ate peanuts and (B) participants during the control period

‘Our results suggest that eating unsalted, skin-roasted peanuts every day can support brain health as we age,’ Joris added.

Even with roughly 340 extra calories per day from the peanuts, participants’ body weight remained mostly stable, likely because they naturally adjusted their intake of other foods.

The study has some limitations, as participants knew when they were eating peanuts, which could have influenced their behavior or self-reports, though the researchers analyzing brain and memory results were unaware of who was in which phase.

While the study clearly links peanut consumption to better brain blood flow and memory, the exact mechanism is not fully understood. 

It remains unclear whether the benefits come primarily from L-arginine, the compounds in the peanut skins, the healthy fats, or a combination of these nutrients.

‘One important point is that the peanuts were unsalted and skin-roasted,’ the researcher added. 

‘The skin contains many antioxidants and fiber that may contribute to the beneficial effects.’