But perhaps their best-known contribution to human health is their ability to improve brain function and reduce the risk of cognitive decline in older adults. This benefit, according to studies, stems from their abundance of plant-based omega-3 fatty acids and polyphenols, which can reduce brain inflammation. Chronic brain inflammation is believed to be a key driver of neurodegenerative disorders like Alzheimer's disease and dementia.
A clinical trial conducted by researchers from the University of South Australia (UniSA) has found that walnuts also provide mental health benefits. Daily walnut consumption in a small group of undergraduate students was shown to effectively reduce stress and depression and counteract the negative effects of stress on the gut and metabolic health.
How stress impacts mood, gut microbiota and metabolic markers
Stress can affect all systems of the body and is known to cause a number of symptoms. Among these, dramatic changes in mood and appetite, pain, depression and stomach discomfort are the most common.
Your body produces high amounts of cortisol when you are under a lot of stress. Cortisol is the primary stress hormone released as part of the body's fight-or-flight response to stimulate the liver to produce more glucose and facilitate the conversion of nutrients into energy. These are meant to naturally boost energy levels to enable the body to better respond to the cause of stress.
But having persistently high cortisol levels, as in the case of chronic stress, has negative consequences, particularly for mental health. Studies show that an elevated cortisol response is associated with acute and severe forms of major depressive disorder. Abnormal cortisol levels can also lead to the development of Cushing syndrome, a condition that causes weight gain, high blood pressure and mood changes.
Aside from mood, stress also has a negative impact on the gut and commensal bacteria. Research has found that during times of stress, distress signals reach the gut via a pathway mediated by immune cells. This event triggers inflammation, which favors the growth of certain gut bacteria that could become pathogenic when allowed to flourish.
A stress-induced shift in gut microbial composition can also cause an imbalance (dysbiosis) and increase the permeability of the gut barrier, resulting in a "leaky gut" that allows potentially harmful bacteria to seep into circulation. Gut dysbiosis and decreased diversity of gut commensal bacteria have been linked to chronic conditions like obesity and Type 2 diabetes, and neurodegenerative disorders like Alzheimer's and Parkinson's in the elderly.
Multiple studies have also reported a link between stress and metabolic disorders. In fact, chronic stress is considered an important risk factor for metabolic syndrome, a cluster of conditions that occur together and increase a person's risk of heart disease, stroke and diabetes. Other risk factors used to diagnose metabolic syndrome include excess belly fat, high blood pressure, high triglyceride levels, low high-density lipoprotein cholesterol (good cholesterol) and high fasting blood sugar.
According to studies, stress has a direct influence on these metabolic markers. For instance, a report published in the journal Medicine found that chronic stress can increase blood triglyceride and low-density lipoprotein (bad cholesterol) levels and decrease high-density lipoprotein. High cortisol levels have also been linked to abdominal obesity as it can trigger uncontrollable eating.
And because cortisol promotes the production of glucose, chronic stress can keep your blood sugar elevated and put you at risk of developing Type 2 diabetes. This is why effective stress management is very important, especially for people constantly exposed to various stressors in their daily lives. Having three of the five risk factors mentioned above is enough to be diagnosed with metabolic syndrome.
Walnuts can help students deal with academic stress
Academic stress is a chronic stressor that negatively affects the mental health of university students. According to the National Alliance on Mental Illness, about 75 percent of mental health disorders develop prior to the age of 24. Because undergraduate students are continually subjected to academic stress, they are particularly prone to depression. A 2022 study corroborates this, with survey results showing an overall 135 percent increase in depression and a 110 percent increase in anxiety among college students across the U.S. from 2013 to 2021.
As multiple studies have pointed out, chronic stress leads to the dysregulation of the body's stress response system, which results in chronically high levels of cortisol. Excessive amounts of cortisol have been shown to impair learning and memory and disrupt the mesolimbic dopaminergic system, a key component of the brain's reward pathways. The resulting decrease in reward sensitivity is what ultimately leads to feelings of depression.
But recent investigations into dietary interventions that could help prevent stress-induced depression have found that walnut consumption exerts positive effects on both cognition and mental health. These benefits appear to be linked to walnuts' abundance of brain nutrients, such as omega-3 fatty acids, a-linolenic acid and tryptophan, and compounds that support cognition, such as melatonin, polyphenols, folate and vitamin E.
Thanks to these brain-supporting components as well as walnuts' fiber content, regular walnut intake has also been reported to promote gut microbial diversity. Because of the complex bidirectional interactions between the brain, the gut and gut commensal bacteria, researchers believe that the positive changes in gut microbial composition brought about by walnut consumption could also influence brain function and mood. (Related: Can walnuts prevent inflammation and brain decline?)
To explore how walnuts can help circumvent the adverse effects of academic stress, UniSA researchers recruited 80 undergraduate students and divided them into treatment and control groups. Half of the participants were asked to eat approximately 56 grams (g) of walnuts daily, while the other half (control) were asked to refrain from eating any nuts or fatty fish for 16 weeks. The 16-week study duration was based on UniSA's teaching semester and examination period.
During the course of the clinical trial, the participants answered questionnaires regarding their mental health at designated intervals. The researchers also took blood and saliva samples to monitor changes in the participants' metabolic biomarkers and sleep quality. Data confirmed that academic stress had a negative impact on the students' self-reported mood and mental health status. It was also associated with lower gut microbial diversity in females.
In contrast to the control group, which reported increased stress and depression in the lead-up to exams, the walnut group reported a significant drop in feelings associated with depression. Daily walnut consumption also reduced their risk of metabolic syndrome as well as their total cholesterol levels during and at the end of the semester.
In addition, eating walnuts helped reverse stress-induced changes in gut microbial composition. Results showed that walnut consumption stabilized gut microbial diversity throughout the periods of stress, but only for female students. Because there weren't enough male participants, the study could not determine the effects of academic stress and walnut consumption on males.
Another benefit of walnut consumption observed in the treatment group was improved sleep quality. Participants in the walnut group noted that it was easier for them to get to sleep and sleep through the night after adding walnuts to their daily diet. This improvement in sleep quality made them feel more refreshed throughout the day, which no doubt also affected their mood and brain performance positively.
Taken together, the study's findings suggest that eating walnuts is beneficial to students as it can protect against the negative effects of academic stress on mental, gut and metabolic health.
Read more about the health benefits of walnuts at Superfoods.news.
Watch this video to learn about simple yet powerful techniques to reduce stress from life coach Tim Brownson.
This video is from the Alternative Health Concepts on Brighteon.com.
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Sources include:
Aging-US.com [PDF]
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