Year Published: 2021
Isabella Parilli-Moser, Inés Domínguez-López, Marta Trius-Soler, Magda Castellví, Beatriz Bosch Sara Castro-Barquero, Ramón Estruch, Sara Hurtado-Barroso, Rosa M. Lamuela-Raventós
The three-arm, parallel-group randomized controlled trial was conducted from November 2019 to June 2020 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 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 control had a similar macronutrient composition as the roasted peanuts and peanut butter but was free of phenolic compounds and fiber. Consumption of the peanut products began after a two-week, peanut-free period in advance of the study. Study participants 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, a phenolic compound also present in peanuts. In addition, other nuts were excluded from the diet. At the beginning and end of the study, trained personnel assessed the cognitive functions of participants, administering in a standard order a broad range of validated neuropsychological tests and mood disorder questionnaires. The tests evaluated the three main cognitive domains – memory, executive function and processing speed. The Hospital Anxiety and Depression Scale, validated for the Spanish population, was also used to detect anxious states and depressive states.
Results showed that consumption of peanuts and peanut butter seemed to improve cognitive functions and reduce stress in healthy young adults. Researchers point to the polyphenols in peanuts that likely aided memory, executive function and processing speed and resulted in a reduction of cortisol, anxiety and depressive levels in a control group of mostly college students. “The improvement of memory function and stress response after consuming regular peanuts and peanut butter seem to be related to the mental health effects of bioactive compounds such as resveratrol and p-coumaric acid found in peanuts, as well as the increased level of short chain fatty acids and very long chain saturated fatty acids in plasma and feces associated with peanut consumption,” says Dr. Rosa M. Lamuela-Raventós, the lead researcher from the Department of Nutrition, Food Sciences and Gastronomy, XIA, School of Pharmacy and Food Sciences, at the INSA-University of Barcelona and CIBEROBN.