A new study published in Clinical Nutrition links the consumption of nuts to a decreased risk of depression in middle-aged to older adults. The study, conducted using the UK Biobank resource, found that daily consumption of up to 30 grams of nuts is associated with a 17% lower risk of developing depression in adults over a 5.3-year follow-up period.
This large-scale study was conducted on 13,504 middle-aged and older adults in the UK, with researchers from various institutions such as Universidad de Castilla-La Mancha, Universidad de la República, Universidad Autónoma de Chile, and Universidade Estadual de Londrina.
The authors write:
“Depression is among the most common mental disorders… complementary lifestyle-oriented approaches have shown promising effects in preventing depression and alleviating depressive symptoms. Therefore, it is recommended that mental health systems emphasize a multidimensional framework focused on lifestyle strategies to prevent depression.”
The authors begin from a conception of depression as arising from a wide variety of interconnected causes in all realms of life, including emotion, behavior, and cognition — while the brain may be implicated, neurotransmitters do not exist in a vacuum. As a result, depression is intertwined with personal experiences and daily routines. Mental health can also be impacted by lifestyle and dietary changes.
Researchers used data from UK adults participating in the UK Biobank cohort between 2007–2012 (baseline) and 2013–2020 (follow-up). A biobank is an archive of biological collections from humans, including DNA and tissue samples. It also serves as a library of information volunteered by participants and can be used for healthcare and medical research. In this case, the UK Biobank is one of the largest biobanks on earth and yielded more than 13,000 participants for this longitudinal study.
Information about nut consumption was gathered using the Oxford WebQ 24-hour questionnaire, while depression was identified through self-reported physician diagnosis or antidepressant use.
Participants’ data could fall into three categories: no nut consumption, moderate consumption (a partial serving or one serving), and high consumption (more than one serving). These classifications were created based on the number of servings consumed daily, where one serving was ~30g of any nut.
Participants were considered depressed based on whether or not they self-reported depression to a physician or if they were prescribed antidepressants. Covariates were also considered in the data analysis, so age, BMI, smoking habits, loneliness, and comorbidities were all accounted for in the results.
After a mean follow-up of 5.3 years, out of 13,504 participants, 1,122 (8.3%) incident cases of depression were identified. Daily consumption of up to one serving (30 grams) of nuts, such as walnuts, almonds, Brazil nuts, cashews, hazelnuts, and pistachios, was associated with a reduced risk of depression. This association was consistent, regardless of all potential confounders considered, such as BMI status, lifestyle behaviors, and health factors.
Participants who moderately consumed nuts (a serving or less than one serving each day) were 17% less likely to have depression when compared to participants who did not consume nuts whatsoever.
“Since diet is a modifiable lifestyle factor,” the authors write, “future long-term clinical trials should evaluate whether nut consumption is an effective strategy to prevent depression in adults. Specifically, understanding the optimal dose and mode of preparation of nuts to promote the greatest mental health benefits will guide the development of more specific dietary recommendations for reducing the risk of depression.”
The study is part of the “Nuts4Brain Project” and is funded by the Ministry of Science and Innovation of Spain, the European Union NextGenerationEU program, the Instituto de Salud Carlos III in Spain, and the FEDER Funds. Bruno Bizzozero-Peroni was supported by a grant from the University of Castilla-La Mancha, Spain, co-financed by the European Social Fund.
While the study provides valuable insights into the potential protective effects of nut consumption on depression, it has some limitations. The findings are based on self-reported data for depression, for instance. Moreover, the study primarily focuses on middle-aged and older UK adults, and the results may not be generalizable to other age groups or populations.
This research comes off the heels of other studies that highlight how similar dietary changes can improve mental health, such as the popular “Mediterranean diet.” What makes this study so different is that it is supported by robust data from the UK Biobank, and its tremendous sample size combined with its consideration for confounding variables makes its results that much more worthwhile.
This study adds to the growing body of evidence suggesting that dietary changes, such as nut consumption, may play a role in preventing or mitigating depression. However, more research, including long-term clinical trials, is needed to understand the optimal dose and preparation methods for maximizing mental health benefits. By recognizing the multifaceted nature of depression, including psychosocial, behavioral, and environmental factors, a holistic approach that emphasizes lifestyle strategies can be an essential part of mental health care.
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Bizzozero-Peroni, B., Fernández-Rodríguez, R., Martínez-Vizcaíno, V., Garrido-Miguel, M., Medrano, M., Jiménez-López, E., & Mesas, A. E. (2023). Nut consumption is associated with a lower risk of depression in adults: A prospective analysis with data from the UK Biobank cohort. Clinical Nutrition, 42(9), 1728–1736. https://doi.org/10.1016/j.clnu.2023.07.020 (Link)
Observational studies like this are useless. They cannot control for all the various factors between those who eat nuts and those who don’t. In addition, self reported data are notoriously inaccurate. The supposed 17% reduction in depression is no doubt the relative risk reduction. What is the more meaningful absolute risk reduction and why wasn’t it mentioned? Because it’s unimpressively low?
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Hi, Marie.
Are you suggesting that there is, indeed, such a medical condition as “clinical depression” or any other kind of depression, and, if so, I wonder if you could offer a definition of it, please?
Thank you for your very interesting comments…on paper which leaves me (even while I believe that many tree nuts contain densely packed nutrients essential to optimal physical health) almost speechless.
Best wishes.
Tom.
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“Hazard regression models estimating the predictive ability of nut consumption for the risk of developing depression were adjusted for sociodemographic, lifestyle, and health confounders.” – So states the Summary of that paper, but without revealing, any more than Liam does, if other dietary constituents were considered.
My suspicion, having lived some 47 years on one or other of “the British Isles,” is that, while “depression” or human hopelessness or suffering is neither a disease or disorder in Great Britain or in Ireland, there is a great chance that those adult citizens enlightened/educated/ affluent/motivated enough to regularly graze on tree nuts are likely to be making other dietary and lifestyle choices consistent with a happier human existence…and the summary of the paper above does not reveal to what if any extent this was taken into account by researchers in lands far, far away from them.
Indeed, simply deciding to CHOOSE supposedly “healthier” snacks such as nuts rather than higher carb, less nutrient dense “trash” may indicate a more proactive attitude towards one’s health, with all that that suggests/entails…
If only I could manage to find and for long enough to stick to that optimum diet, possibly much richer in tree nuts and in oily fish than my present one, which brings me to and maintains me at my highest level of functioning, whatever that might look like, but presumably the most easeful, joyful, humorous and creative, then maybe I could crack this nut?
RDA’s, or recommended daily allowances, not only originally, notoriously crudely formulated as estimates of what minimal daily intake levels might prevent frank, obvious, detectable, identifiable clinical signs of that nutrient’s deficiency in the ?average adult male, adult female or child.
Since then, we have learned so much more about human and animal nutrition, and about human consciousness.
We may overlook the facts that
(i) many nutrients, rather than having any optimal daily requirement, may, like proteins, caffeine and fluids, have optimal intakes at various intervals throughout a day, while others, such as fat-soluble vitamins and certain minerals, may be fine if taken in every few days or more;
(ii) the Canadians, for instance, may not have been at all foolish in outright abolishing dairy products as “a food group;”
and
(iii) any assumption that we can even articulate what “optimal human health” might be may now need to be radically re-addressed, perhaps bearing in mind that, while our brains may endlessly urge us to feed them glucose, our minds (and more?) may have longer and broader agendas in mind, and impel us to endlessly seek those foods and diets which most efficiently promote our ascents to higher levels of consciousness (and/or to “spiritual awakenings”) – whatever these might look like?
I often reflect on the story of the Salmon of Knowledge or of Wisdom or of Enlightenment or of Spiritual Awakening, https://en.wikipedia.org/wiki/Salmon_of_Knowledge .
It fascinates me that this salmon was reputed to have eaten hazelnuts, and that, nowadays, we are told that both tree nuts, like the hazelnut, and oily fish, like the salmon, are rich in the essential fatty acids so vital for optimal brain function.
It intrigues me also to consider what Western societies might look like if the ancient Romans had been busy conquering ancient Ireland instead of ancient Israel around the year Zero, and appropriating an ancient ?Celtic rather than an ancient Jewish mythology: Would we have long since all become enlightened – not so much from eating more hazelnut-guzzling salmon as from not beating ourselves up over having fallen in/from Eden, or considering ourselves sinful or disordered miscreants and, instead, understanding that enlightenment is something which can and must inevitably happen to us all, regardless of our best intentions?
“Depression risk 50 times lower in Japan due to fish intake
IRISH people are 50 times more likely to develop depression than the Japanese because we don’t eat enough fish, a conference was told in Dublin yesterday.”
https://www.irishexaminer.com/news/arid-20084767.html
I’d dare suggest that Ireland’s lower fish intake may have much to do with its Roman Catholic history. So, too, though, may the optimism or otherwise of its population relative to that of the Japanese?
“But why on earth,” you may ask, “should it be necessary for man to achieve, by hook or by crook, a higher level of consciousness? This is truly the crucial question, and I do not find the answer easy. Instead… I can only make a confession of faith: I believe that, after thousands and millions of years, someone had to realize that this wonderful world of mountains and oceans, suns and moons, galaxies and nebulae, plants and animals, exists. From a low hill in the Athi plains of East Africa I once watched the vast herds of wild animals grazing in soundless stillness, as they had done from time immemorial, touched only by the breath of the primeval world. I felt then as if I were the first man, the first creature, to know that all this is. The entire world round me was still in its primeval state; it did not know that it was. And then, in that one moment in which I came to know, the world sprang into being; without that moment it would never have been. All Nature seeks this goal and finds it fulfilled in man, but only in the most highly developed and most fully conscious man. (CW 9i, §177)”
Why should it be necessary?
Presumably, as Carl very well knows by now, because that is where the best love and laughter and sex and jokes and music and art are, among other things?
So why not? But why nut?
Possibly because many (Western) populations derive proportionately so many of their calories from carbs and saturated fats, and so seriously lack plant-derived pufa’s (polyunsaturated fatty acids) that they cannot themselves synthesize sufficient for “health?”
The following may seem a stretch, but, for the record, walnut comes in at #8:
https://turmericaustralia.com.au/12-foods-that-look-like-body-parts-theyre-benefiting/
And, for the other record, weirdlier still, perhaps, is that “Julian” of Norwich reported that, though she fully expected that the hazelnut she saw in the palm of her hand, representing all of Creation, would have disappeared when she came to from that “showing” of hers…it had not: Perhaps the hazelnut was an essential part of her own spiritual awakening?
Thank you, Liam, for bringing this piece of research to our attention –
as well as reminding us that
psychiatrymassive sample size, alone, cannot create causation from correlation,
that “depression” is, if anything, a symptom, and not a sign nor a syndrome nor an illness nor a disorder,
and that a symptom is, by definition, something which only the person experiencing it can report.
Best wishes, and God rest ye merry, all.
Tom.
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