Consuming nuts during times of stress can improve mental health and overall well-being

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Walnut consumption was associated with increased improvements in self-reported mental health and stress. It was also linked to improved sleep quality and metabolic biomarkers.

Walnuts contain omega-3 fatty acids, melatonin, and other vitamins and nutrients associated with mental and gut health.

Stressed university students might want to add walnuts to their daily diet in the weeks leading up to their next exam.

A new clinical trial of undergraduate students during their university studies has shown positive effects of walnut consumption on self-reported measures of mental health and biomarkers of general health.

The University of South Australia study, published in the journal Nutrients, also suggests that walnuts may counteract the effects of academic stress on the gut microbiota during periods of stress, especially in females.

Lead researchers, Ph.D. student Mauritz Herselman and Associate Professor Larisa Bobrovskaya, say the results add to the growing body of evidence linking walnuts with improved brain and gut health.

“Students experience academic stress throughout their studies, which has a negative effect on their mental health, and they are particularly vulnerable during exam periods,” Herselman says.

Eighty undergraduate students split into treatment and control groups were clinically assessed in three intervals, at the beginning of a 13-week university semester, during the examination period and two weeks after the examination period. Those in the treatment group were given walnuts to consume daily for 16 weeks over these three intervals.

“We found that those who consumed about half a cup of walnuts every day showed improvements in self-reported mental health indicators. Walnut consumers also showed improved metabolic biomarkers and overall sleep quality in the longer term.”

Students in the control group reported increased stress and depression levels in the leadup to exams but those in the treatment group did not. The walnut consumers also reported a significant drop in feelings associated with depression between the first and final visits, compared to the controls.

Previous research has shown that walnuts are full of omega-3 fatty acids, antioxidants, as well as melatonin (sleep inducing hormone), polyphenols, folate and vitamin E, all of which promote a healthy brain and gut.

“The World Health Organization has recently stated that at least 75 percent of mental health disorders affect people under the age of 24 years, making undergraduate students particularly vulnerable to mental health problems,” Herselman says.

Assoc Prof Larisa Bobrovskaya says mental health disorders are common in university students and can adversely affect students’ academic performance and long-term physical health.

“We have shown that consuming walnuts during stressful periods can improve mental health and general wellbeing in university students, as well as being a healthy and delicious snack and a versatile ingredient in many recipes, to fight some negative effects of academic stress,” Assoc Prof Bobrovskaya says.

“Due to fewer numbers of males in the study, more research is needed to establish sex-dependent effects of walnuts and academic stress in university students. It’s also possible that a placebo effect might have come into play as this was not a blind study.”


Nuts are energy dense foods rich in bioactive macronutrients, micronutrients and phytochemicals. The unique composition of nuts is critical for their health effects. Indeed, there are consistent evidences from epidemiologic and clinical studies of the beneficial effects of nut consumption on risk of CHD, including sudden cardiac death, as well as on diabetes in women, and on major and emerging cardiovascular risk factors, as summarized in Table 3.

Table 3

The effect of nut consumption on cardiovascular risk factors. Summary of scientific evidence.

VariablesEffectLevel of evidence
Epidemiologic studies
Coronary heart diseaseDecrease++
Sudden cardiac deathDecrease+
Ischemic strokeNo change+
Heart failureNo change+
HypertensionDecrease+/-
DiabetesNo change/decrease+/-
CancerNo change/decrease+/-
Gallstone diseaseDecrease+
Complications of diverticular diseaseDecrease+
Inflammatory markersDecrease+
Body weightNo change/decrease++
Clinical studies
Blood cholesterolDecrease++
Insulin sensitivityNo change/increase+/-
Blood pressureDecrease+
OxidationNo change/decrease+/-
InflammationNo change/decrease+/-
Vascular reactivityIncrease+
Body weightNo change++
Visceral adiposityDecrease+
+/-, equivocal evidence;
+, limited evidence from few studies;
++, consisting evidence in several studies.

The evidence to date is convincing that including nuts in a healthy dietary pattern will extend the cardioprotective effects beyond those attributable to the components of any healthy diet exclusive of nuts. Importantly, these effects take place without undue weight gain, or even with reduced adiposity, and target multiple cardiovascular risk factors and mechanisms, which help explain why nuts so potently reduce the risk for CHD.

There is also emerging evidence from acute studies that single meals enriched with nuts can have a beneficial impact on postprandial events related to atherogenesis, such as glucose and triglyceride raises, inflammation, and endothelial activation. Understanding the underlying biological mechanisms of the effects of nuts on mediators of CHD, obesity, metabolic syndrome, diabetes, and cancer should help in the design of diets that include nuts to maximally reduce chronic disease risk.

The vegetarian, Mediterranean, and many Asian diets are traditional plant-based dietary patterns that include nuts and are reputed for their beneficial effects on health.

A healthy dietary pattern is high in vegetables, fruits, legumes, nuts, whole grains, and lean protein sources and low-fat dairy products [10]. Nuts are a popular and important source of unsaturated fat and high-quality vegetable protein in vegetarian diets, where they rank high on the list of foods most frequently consumed, above meat substitutes [9,148].

The optimal nutrient composition of nuts and the impressive evidence gained from epidemiologic and clinical studies on their health benefits indicates that they are an indispensable contribution to a well-balanced vegetarian diet. Also, knowledge has accumulated that dietary patterns close to the Mediterranean diet, in which nuts are a key food item, are associated with many beneficial health outcomes [16,149].

Indeed both exposure to the Mediterranean diet and frequency of nut consumption are among the dietary factors with stronger evidences for a causal link with CHD prevention [150]. Ongoing research like the large randomized PREDIMED trial, wherein one daily serving of mixed nuts within the context of the Mediterranean diet is provided to participants at high cardiovascular risk in one arm of this six-year study [80], might eventually settle the critical issues of whether, in comparison with a healthy control diet without nuts, a healthy diet supplemented with one daily serving of nuts prevents cardiovascular events and development of other prevalent chronic disorders, including diabetes, cancer and neurodegenerative diseases.

Table 1

Average nutrient composition of nuts (per 100 g).

NutsEnergy (kJ)Fat (g)SFA (g)MUFA (g)PUFA (g)LA (g)ALA (g)Protein (g)Fiber (g)Folate (μg)PS (mg)
Almonds241850.63.932.212.212.20.0021.38.829120
Brazil nuts (dried)274366.415.124.520.620.50.0514.38.522NR
Cashews231446.49.227.37.87.70.1518.25.925158
Hazelnuts262960.84.545.77.97.80.0915.010.411396
Macadamia nuts300475.812.158.91.51.30.217.96.011116
Peanuts222049.26.824.415.615.60.0025.88.5145220
Pecans288972.06.240.821.620.61.009.28.422102
Pine nuts (dried)281668.44.918.834.133.20.1613.73.734141
Pistachios233244.45.423.313.513.20.2520.69.051214
Walnuts273865.26.18.947.238.19.0815.26.49872

Data for raw nuts, except where specified. SFA, saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; LA, linoleic acid; ALA, α-linolenic acid; PS, plant sterols; NR, not reported.

Source: US Department of Agriculture Nutrient Data Base at: http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl (Accessed on 26 April 2010).

Table 2

Calcium, magnesium, sodium and potassium content of nuts and other foods in mg/100 g of edible portion.

NutsCalciumMagnesiumSodiumPotassium
Almonds2482751728
Brazil nuts1603763659
Cashew nuts3729212660
Hazelnuts1141630680
Macadamia nuts851305368
Peanuts9216818705
Pecans701210410
Pine nuts162512597
Pistachios10712111025
Walnuts981582441
Other foods
Apples (with skin)651107
Bananas5271358
Beans (white, cooked)90636561
Broccoli (cooked)402141293
Cheese (cheddar)7212862198
Chickpeas (cooked)49487291
Ham24221304287
Lettuce (romaine)33148247
Milk1131040143
Rice (white, cooked)1038135
Sardines (canned in oil)38239505397
Spinach (cooked)1368770466
Tomato10115237
Veal (cooked)222687325
Wheat bread7286527252

Source: US Department of Agriculture Nutrient Data Base at: http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl (Accessed on 26 April 2010).

reference link : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257681/


Original Research: Open access.
The Effects of Walnuts and Academic Stress on Mental Health, General Well-Being and the Gut Microbiota in a Sample of University Students: A Randomised Clinical Trial” by Mauritz F. Herselman et al. Nutrients

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