Research from the University of Barcelona on the gut microbiota has found that daily consumption of peanuts and peanut butter can produce compounds in the gut that help improve memory and reduce stress response, including anxiety and depression, in healthy young adults. Findings from the Aristotle study were published online in theJournal of Functional Foods this September and shared by The Peanut Institute. 

The study was conducted to explore what’s known as the gut-brain axis, which is a relatively new area of research that examines the biochemical communication between the gut and brain. The researchers used a novel method to identify phenolic compounds derived from digesting peanuts and peanut butter and how those compounds can promote better brain health.

When compared to the control group, researchers found that those who consumed peanuts and peanut butter had higher levels of microbial phenolic metabolites (MPMs), which are compounds that can cross the blood-brain barrier and reach brain cells to protect them. Earlier results from the Aristotle trial showed that participants who consumed peanuts and peanut butter experienced an improvement in memory and stress response, largely due to polyphenols in peanuts. 

The new findings confirm the ability of the gut microbiota to potentially produce compounds from peanut polyphenols that can improve brain response. The study showed that MPMs were associated with an improvement in memory and reduced stress. 

“Peanuts and peanut butter may have a beneficial effect on the gut microbiota because they are rich in prebiotic fiber and polyphenols. Due to their very poor absorption, fiber and most polyphenols directly reach the colon, where they are metabolized by the gut microbiota, giving rise to new compounds (MPMs), which can have beneficial effects on the brain."

— Dr. Isabella Parilli Moser, First Author, Aristotle Study

Dr. Sara Hurtado-Barroso, co-author of the study, adds, “Prebiotic substances present in peanuts and peanut butter, such as polyphenols, may positively affect cognition and mood by promoting production of microbial phenolic metabolites.” 

The six-month, randomized controlled trial was conducted with 63 healthy participants (44 females and 19 males) who were 18 to 33 years of age. The participants, who were mostly students, were from the University of Barcelona in Spain and consumed either one handful (25 grams) a day of roasted peanuts with skins or two tablespoons (32 grams) a day of peanut butter or two tablespoons (32 grams) a day of a control butter.

The young men and women followed their regular diet and consumed the peanut products at any time of the day. Wine, grapes, dark chocolate with more than 70% cacao, and berries were excluded from the participants’ diets due to their high levels of resveratrol, an antioxidant present in peanuts. In addition, other nuts were excluded from the diet due to similar nutritional composition. 

“More and more research is looking at our gut microbiome and how it plays an integral role in affecting our immune system, brain health, and other body functions,” said Dr. Samara Sterling, a nutrition scientist and research director for The Peanut Institute. “These findings are exciting because the students consumed a relatively small amount of peanuts each day but the impact on their memory and mood was statistically significant.”

About the Research: 

The research is part of Dr. Isabella Parilli-Moser’s PhD thesis, mentored by Dr. Rosa M. Lamuela-Raventós at the University of Barcelona (Department of Nutrition, Food Sciences, and Gastronomy, XIA, School of Pharmacy and Food Sciences, at the INSA-University of Barcelona and CIBEROBN). 

It was supported by funding from The Peanut Institute, PID2020-114022RB-I00 and CIBEROBN from the Instituto de Salud Carlos III, ISCIII from the Ministerio de Ciencia, Innovación y Universidades, (AEI/FEDER, UE), Generalitat de Catalunya (GC) [2021-SGR-00334]. INSA-UB is Maria de Maeztu Unit of Excellence (grant CEX2021-001234-M funded by MICIN/AEI/FEDER, UE). None of the funders had a role in the study design, implementation, analysis, or interpretation of the data or the writing of the manuscript.