How Exercise and Nutrition can Effect the Role of the Immune System in Mental Health Disorders

The Immune System and Mental Health

Previous posts on our site have talked about the impact of nutrition and exercise on mental health disorders. In the research, for both of those posts, a common theme was the link between the immune system and mental health. The immune system is the body’s protective mechanism from damaged cells, pathogens and other compounds [3]. However, there can be circumstances where the immune system can be compromised and can become over or under-active. Increased activity of the immune system can lead to mental health disorders and psychiatric disorders [4]. These mental health disorders occur due to a series of changes which take place neuroimmune changes which take place, leading to reductions in the production of neurotransmitters. This article is going to talk about the immune system’s role in mental health disorders, how exercise and nutrition improve immunity, and why.

Inflammation

Inflammation is one of the initial responses made by the immune system after trauma and is an essential aspect of the bodies healing process [3]. It can be triggered by pathogens, damaged cells, and toxic compounds among other things. Although inflammation is necessary for healing, it mustn’t is important that it does not become excessive as this can lead to further damage or disease. Inflammation in otherwise healthy individuals can predict the development of mental health disorders in subsequent months, or years [4]. It has also been shown that there is an increase in inflammatory mediators within people with conditions such as depression, anxiety, schizophrenia, and psychosis [1]. In these individuals with high baseline levels of inflammation, it is effective to treat psychological disorders with not only antidepressants, or antipsychotics, but also with anti-inflammatories [4,6].   

Trauma

 In our article on PTSD, we mentioned trauma in early life increases the risk to mental health disorders later on. Interestingly, It is also shown that trauma early in life also make the immune system more active [4]. In addition to this, the immune system can become active following interpersonal violence, or maltreatment, socioeconomic disadvantage, or other forms of chronic stress. This immune response of inflammation is a risk factor for mental health disorders. This may be because of the presence of certain immune cells in the brain causes alterations in the brains function and reduce serotonin activity along with neuroplasticity and neurogenesis [4].this may also be because of inflammation in the digestive tract reducing the production of serotonin and other neurotransmitters. 

It has been shown that people with depression are at greater risk of infection due to changes in their immune systems and may be less responsive to vaccinations [5]. 

Autoimmune and respiratory conditions

 Inflammatory disorders are also examples of where this inflammation becomes excessive and damages the body [1]. Examples of these conditions are Rheumatoid Arthritis (RA), causing inflammation of cartilage structures, and Irritable Bowel Syndrome (IBS), causing inflammation in the digestive tract. It has been shown that people with inflammatory disorders are more likely to suffer from mental health disorders than the average person due to inflammation [1].

 This inflammation can not only occur in the digestive system, as seen with IBS, and in connective tissue, as seen in RA, but also the circulatory, respiratory, endocrine, nervous, and reproductive systems [3].

 Alzheimer’s disease and Multiple Sclerosis (MS) are both examples of when an overactive immune system affects the nervous system[1,2]. Immunity is a risk factor for Alzheimer’s and there is also an increased inflammatory response in the brain present in people with the disease [1]. MS is an autoimmune disease where the immune cells in the brain and spinal cord attack the myelin sheath with encases nerves [2]. 

How to Improve Immunity

So we know some of the ways the immune system impacts our mental health, so now we need to go through how to make the immune system work more effectively without becoming overactive and causing excessive inflammation. The two most common ways outside of medication are exercise and diet.

Exercise 

Exercise has been shown to alter the immune system and reduce inflammation related to depression [8]. It has also been seen to improve the mental health of patients with inflammatory disorders. This can be achieved via an increase in the activity of the vagal nerve. The vagal nerve connects the brain to the abdominal region and restrains the production of pro-inflammatory factors and neurotoxic metabodies. The increased vagal tone also leads to an anti-inflammatory reflex and reduces systemic inflammation. 

Exercise also helps to maintain muscle mass. This, in turn, helps to maintain mitochondrial biogenesis, reducing the risk of multiple diseases including mental health disorders like depression [8]. 

Cortisol is released by the body when stress is placed during exercise. As well as stopping the secretion of insulin, cortisol also inhibits pro-inflammatory immune cells, reducing overall inflammation [8].

Toll-Like Receptors (TLR) mediate inflammation in the body and their activity is implicated in inflammatory diseases [8]. A sedentary lifestyle can increase the signaling of TLR resulting in an increase in systemic inflammation. It has been shown that both short and long periods of anaerobic training can reduce TLR signaling for hours post-exercise and people who are physically active express reduced TLR activity than inactive people. 

On the contrary, very high training loads can lead to a detrimental anti-inflammatory state, leaving the body at an increased risk of minor infections [8]. This state however is only achieved by elite athletes who train intensely for hours per day.

Nutrition 

The under-consumption of certain nutrients in a diet can lead to the dysregulation of the immune system [8]. For example, not having enough fibre in your diet can reduce the diversity of microbiota in the gut [7]. This is because the fibre stimulates the growth of bacteria [9].  This is important as the gut microbiota constrains the growth of pathogens, reducing the inflammatory immune system response [7]. Therefore not having this diverse gut microbiota increases the risk of inflammation. This then activates an inflammatory reflex of the vagal nerve, reducing the production of neurotransmitters [8]. 90% of the serotonin produced in the body is produced in the gut so if the production is reduced here then you will be a lot more susceptible to mental health disorders [10]. Diversity in microbes can be developed by eating foods with a variety of types of fibre [7]. Mushrooms for example contain many types of fibre which feed gut bacteria and are associated with improved brain function and mood. Eating foods high in probiotics can also increase the diversity of microbiota in the gut as they adhere to the gastrointestinal tract where they colonise [9]. In addition to this, these colonises of probiotics help to maintain and repair the intestinal epithelial barrier, reducing the risk of conditions like irritable bowel syndrome, inflammatory bowel syndrome and obesity being developed there. Yeast and other fermented foods are high in probiotics. 

Both diet and exercise can be used to treat obesity. Reducing obesity can be beneficial to improving mental health as in sufferers of obesity, adipose tissue contains inflammatory cells which keep the body in a chronic state of low-level inflammation [8]. 

Overall

Over the last few posts, you should now have a better understanding of the proactive steps you can take to protect your mental health and how to keep your immune system as effective as possible. Not only that, but a greater understanding of why certain nutrients are important and some benefits to exercise that you may not have thought of before or fully understood. It is important to remember though that although these are all proven ways to improve mental health and psychiatric disorders you may still find it beneficial to talk to a mental health practitioner who may be able to help your root out the source of what you are feeling. This can be achieved through the NHS but the waiting lists may be long, judging by the average waiting time for treatment for PTSD being 4.5 years [11]. There are a variety of private options available and a variety of professionals in different fields, from counsellors to hypnotherapists, to life coaches who can help you. There are even apps on the app store which allow you to instant message counsellors and therapists. This combination of tools at your disposal should aid you in becoming your physically, and mentally best self.  


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References

  1. Taams, L. S. (2019). Neuroimmune interactions: how the nervous and immune systems influence each other. Clinical & Experimental Immunology, 197(3), 276-277.

  2. Kipnis, J. (2016). Multifaceted interactions between adaptive immunity and the central nervous system. Science, 353(6301), 766-771.

  3. Chen, L., Deng, H., Cui, H., Fang, J., Zuo, Z., Deng, J., ... & Zhao, L. (2018). Inflammatory responses and inflammation-associated diseases in organs. Oncotarget, 9(6), 7204.

  4. Pariante, C. M. (2016). Neuroscience, mental health and the immune system: overcoming the brain-mind-body trichotomy. Epidemiology and psychiatric sciences, 25(2), 101-105.

  5. Suzuki, H., Savitz, J., Teague, T. K., Gandhapudi, S. K., Tan, C., Misaki, M., ... & Bodurka, J. (2017). Altered populations of natural killer cells, cytotoxic T lymphocytes, and regulatory T cells in major depressive disorder: association with sleep disturbance. Brain, behavior, and immunity, 66, 193-200.

  6. Guo, X., & Jiang, K. (2017). Is depression the result of immune system abnormalities?. Shanghai archives of psychiatry, 29(3), 171.

  7. Kim, C. S., Byeon, S., & Shin, D. M. (2020). Sources of Dietary Fiber Are Differently Associated with Prevalence of Depression. Nutrients, 12(9), 2813.

  8. Mikkelsen, K., Stojanovska, L., Polenakovic, M., Bosevski, M., & Apostolopoulos, V. (2017). Exercise and mental health. Maturitas, 106, 48-56.

  9. Ashaolu, T. J. (2020). Immune boosting functional foods and their mechanisms: A critical evaluation of probiotics and prebiotics. Biomedicine & Pharmacotherapy, 130, 110625.

  10. DeSantis, N. Nutrition for Mental Health

  11. Foa, E. B., Keane, T. M., Friedman, M. J., & Cohen, J. A. (2020). Effective treatments for PTSD. Guilford Publications.