Walnut consumption may boost mood in men, new research finds
The study, carried out by UNM nutrition professor Peter Pribis, showed that non-depressed healthy, males aged 18-25 had a 28% reduction in overall mood disturbances after eating two ounces of walnuts everyday for eight weeks.
"In the past, studies on walnuts have shown beneficial effects on many health outcomes like heart disease, diabetes and obesity," Pribis said.
"Our study was different because we focused on cognition, and in this controlled randomized trial (CRT) we measured mood outcomes in males and females."
The 64 participants of the study, who represented varied ethnic groups, were asked to eat three slices of banana bread every day for sixteen weeks—eight weeks of banana bread with walnuts and eight weeks of banana bread without the tree nut.
The nuts were finely ground into the dough so the two banana breads were similar in taste and appearance. While eating banana bread with walnuts the participants consumed half a cup of walnuts daily. The mood of the students was measured at the end of each eight-week period.
"We used a validated questionnaire called Profiles of Mood States (POMS)," says Pribis.
"It is one of the most widely used and accepted mood scales in studies on cognition. The test has six mood domains: tension, depression, anger, fatigue, vigor, confusion and also provides a Total Mood Disturbance score (TMD). The lower the TMD score the better the mood."
In this double-blind, randomized, placebo controlled, cross-over feeding trial with walnuts for eight weeks, Pribis observed a significant improvement in mood in young, healthy males.
"There was a meaningful, 28 percent improvement of mood in young men. However we did not observe any improvement of mood in females. Why this is we do not know," he said.
There are several nutrients in walnuts that could be responsible for the improved mood like alpha-Linolenic acid, vitamin E, folate, polyphenols or melatonin. However, this was a whole food study, so in the end it was the synergy and interaction of all the nutrients in the walnuts combined.