A daily handful of walnuts can slash depression particularly among women, a new study.
Eating 24 grams or just under an ounce of walnuts per day lowered the prevalence of depression symptoms.
Depression scores were 26 per cent lower for walnut eaters and eight per cent lower for other nuts eaters compared to those who avoided the tasty seeds.
Those who ate a daily amount of walnuts or nuts had better concentration, higher energy levels, more interest in doing things, and greater self-control of rates of speech and movement.
One in six Britons and Americans will experience depression at some point in their lives and are often prescribed antidepressants.
Adjunct Professor Dr Lenore Arab of the David Geffen School of Medicine at The University of California, Los Angeles, explained: “Although antidepressant usage may be indicative of other underlying problems not just clinical depression, the depressive symptomatology of the population is of concern.
“The various risks related to depression range from suicide to obesity.
“Depression can both cause and be caused by poor diets.
“The percentage of people reporting depression in the US who are obese is 43 per cent.
“Understanding and addressing the possible role of poor diets in depressive symptoms can be of great public health importance.
“It is important to find low-cost interventions, such as dietary changes, that are easy to implement and may help reduce the incidence of depression.
“Walnuts have previously been investigated for their role in cardiovascular and cognitive health, and now we see an association with depression symptoms – providing another reason to include them in a healthy eating plan.”
She noted numerous studies have shown a Mediterranean diet, characterised by their olive oil and nut consumption, to be correlated with lower depression risk.
Prof Arab added: “Tree nuts, often characterised by healthy fatty acid profiles, differ substantially in their nutritional profiles, with walnuts being high in alpha-linolenic acid, a fatty acid associated with brain health in animal studies.
“In addition, the polyphenol content of walnuts differs from other tree nuts in ways that might affect the gut–brain axis related to serotonin production.
“Walnuts have also been associated with positive effects on cognition.”
So the study looked at whether nuts and in particular walnuts, reduced the risk of depression.
It used data from the National Health and Nutrition Examination Survey which asked 26,656 about their dietary intake over the course of one to two days.
They were also asked about their depression symptoms over the past two weeks including how often they experienced factors such as little interest in doing things, trouble sleeping or sleeping too much, feeling tired or having little energy, and trouble concentrating on things.
Prof Arab said: “We found that in the US population, reported nut and walnut use, after controlling for covariates, remains significantly associated with lower prevalence and frequency of depressive symptoms.
“The mean depression scores of individuals, even in the normal range, are lower among the walnut consumers.
“We have also identified the components of depression reported to be less common among walnut consumers.
“These include greater interest in activities, higher energy levels, less hopelessness (among women), better concentration, and greater optimism.
“Nut consumption in general appears advantageous.
“We found this association, however, to be significantly higher among walnut consumers than consumers of other tree nuts.”
While the association between nut consumption and depression scores was consistent for men and women, the effect appeared to be strongest among women, who are more likely to report greater depression symptoms and use of antidepressants, compared to men.
Prof Arab noted: “A growing understanding of the brain–gut connections is revealing pathways by which food choices may affect mood.”
The independent study funded by the California Walnut Commission was published in the journal Nutrients.
By Tony Whitfield