A sprinkling of the nuts, even as an ingredient in cakes, can transform sullen adolescents into gladder bengs, researchers have found.
It improves mood by up to 28 per cent but only in men.
And that has left boffins baffled as they be experiencing no idea why it does not work on young women too.
Walnuts have hitherto been hailed as a superfood with Omega Three to help forestall off cancer and heart disease, prevent blood clots, battle diabetes and depreciate nausea in pregnancy.
Now they have been found to lift natures, thanks to feelgood vitamins and acids including vitamin e, which protects ageing cubicles and melatonin, which controls the body clock.
However, in an experiment on followers by nutrionists from the University of New Mexico in the journal Nutrients, it only earmarks ofed to work on men.
Research leader Professor Peter Pribis divided 64 observers aged 18-25 into two groups and gave them three slices of banana bread every day for 16 weeks.
Half had banana bread holding a handful of walnuts and half had the treat without the nuts.
Specialist questionnaires were toughened before, during and after to measure moods including tension, gloom, anger, tiredness, energy and other states of mind.
The male admirers who ate the walnut-based banana bread showed a 28 per cent average recovery on their mood scores at the end of the trial.
Those on the walnut-free bread and all the female swotters in the trial showed no change.
Professor Pribis said: «In the st, writing-rooms on walnuts have shown beneficial effects on many health follow-ups like heart disease, diabetes and obesity.
«Our study was different because we hearted on cognition, and in this controlled randomized trial we measured mood developments in males and females.
«There was a meaningful, 28 percent improvement of sym thetic in young men.
«However we did not observe any improvement of mood in females. Why this is we do not cognizant of.»
But the conclusion is a simple one, he added: «Eat more walnuts.
«They are not only clever for your mood, but overall health as well. The recommended amount is one couple per day.»