If you’ve been practicing yoga for awhile, you’ve may have uttered the phrase, “Yoga is good for your immune system.”

Lately my students have been asking me, what exactly is the immune system and how does yoga help it?

The yoga world is full of fluffy euphemisms and vague unsubstantiated claims about the benefits of yoga. Sometimes, they are true (and sometimes they aren’t), and I hope that this article will help bridge the disconnect between what yogis say and what yogis know. First, we will go over the basics of the immune system and then return to the issue of yoga and immunity.

There are ten times as many bacteria cells living in/on you as cells that are actually you. These are mostly “good,” or innocuous bacteria that co-exist peacefully within us. Sometimes, the good bacteria get a little out of hand and cause problems. Other times, it is the “bad” bacteria that get the best of us. And sometimes it isn’t bacteria at all.

The immune system is a diverse and expansive system designed to protect the body several ways. Our primary immune defenses are physical, mechanical, and chemical barriers, with the skin being the most important. Other barriers, like the mucous membranes lining our mouth and GI tract, are sticky to trap “bugs.”  Actions like coughing, sneezing, urinating, crying (and even OM-chanting!) help to expel or flush out unwanted bugs out of the body. Most body surfaces and secretions have enzymes designed to break up pathogens (any bug that can make you sick). Saliva, tears, milk, and mucus all contain natural antibacterial enzymes called lysozymes that target and break down the sugars on the cell wall of bacteria. Some body surfaces, such as the skin and lining of the lungs, have tiny little “host defense” enzymes to ward off various fungi, bacteria, and viruses. Most of the bugs that make us sick are single-celled organisms or not even cells at all (e.g. viruses). Thus, there are major structural differences in the cellular architecture of our cells and their cell (or lack there of).  This is the basis of antibiotics and other antimicrobials.

If an organism (virus, worm, bacteria, etc.) breaches the physical barriers of the body, the next line of defense is the innate immune system.

Its called innate, because you are more or less born with it, and its defenses don’t adapt and evolve as your body learns to fight the millions of germs you are exposed to on a daily basis. The innate immune system is understood as the immediate and nonspecific branch of the immune system. It includes things like little white blood cells called macrophages that often reside in specific tissues (dendrocytes in the skin, microglila in the brain, adipocytes in fat, etc.) or patrol the blood stream (neutrophils). Neutrophils are recruited to a site of invasion or injury by chemical signals and arrive at the scene within minutes contributing to the inflammatory process. All these cells are phagocytes (Latin for to eat) and gobble up dead cells or invading organisms, and most of them use the digested material to report back to other immune cells what they found.

One of the hallmarks of the immune system is inflammation.

In the short term, inflammation is good, because it sends little chemical messages that attract immune cells to come attack the foreign invader and get rid of and/or repair damaged tissue.

But left unchecked, the immune system can wreak havoc on the body. This is what happens with chronic stress, auto-immune disorders, and even some mental health issues. Interestingly, the immune system and stress affect our mood and brain function so much that some scientists even use an inflammatory model to study depression.

We know that little immune molecules called cytokines regulate the brain’s ability to change over time (also known as neuroplasticity). This includes the brain’s ability to develop new brain cells, form new memories, and the ability of cells to form the new connections and networks they need to fulfill these roles. Thus, prolonged inflammatory states can also impair cognition and lead to loss of brain mass. In part, this is why people may feel foggy or forgetful when highly stressed.

Stress and inflammatory processes also decreases serotonin, a neurotransmitter that makes us feel good and changes the way the brain and hormones respond to stress. Cortisol is the major stress hormone in the body. Chronic stress interferes with the circadian rhythm of cortisol, and the sleep cycle becomes dysregulated, leading to insomnia and chronic fatigue—further contributing to memory issues and a weakened immune state.

With respect to immunity, cortisol makes certain immune cells less responsive and decreases levels of some immune modulators (chemical signals) that the immune system uses to communicate and coordinate the immune response. This can lead to changes in the distribution of immune cells in the body, so they aren’t where they need to be to fight off the pathogens.

Together, all these things increase the body’s susceptibility to illness.

So, it [immunity] is a balance. Too much of an immune response is bad and results in the body hurting itself. Too little of an immune response impairs the body’s ability to protect us from pathogens. In may ways, yoga helps balance the levels of immune activity by dialing down the stress drive behind chronic inflammation and resulting disease. More specifically, yoga has been shown to decrease activity of the more severe and nonspecific arm of the immune system (Th1 arm) that can become overactive with chronic stress, which causes our bodies to get caught in the crossfire. Yoga and similar exercise regimens reduce cortisol. Yoga is also known to increase oxytocin, a hormone released during orgasm or breastfeeding, which may indirectly suppress cortisol secretion. With cortisol levels in check, the body is better able to regulate sleep, mood, and fight disease.

In other ways, yoga turns up the immune system’s ability to fight. Generally speaking, when stress levels go down, the more specific part of the immune system functions better, so the immune system is activated to more appropriately target pathogens.  Yoga also increases activity of our immune system’s natural killer cells, which helps to clear out pathogens. Additionally, some studies report that yoga can increase cell lifespan of certain immune cells and raise antioxidant levels, further bolstering the immune system. Much of what we hear about yoga inversions and yoga is similar to that of the immune benefits of cardiovascular exercise. Yoga can improve circulation of blood and lymph, which gets things moving in the body so that toxins and bugs can be filtered out by the liver and kidneys or immune system, respectively.

Overall, the combination of stress reduction via mediation and breath control coupled with the exercise and inversion components of yoga support healthy levels of immune activity by decreasing stress hormones and maintaining healthy levels of immune activity.

 

Sources: 

Akhtar P, Yardi S, Akhtar M. Effects of yoga on functional capacity and well being. Int J Yoga. 2013 Jan;6(1):76-9. doi: 10.4103/0973-6131.105952. PubMed PMID: 23439856; PubMed Central PMCID: PMC3573548.

Arora S, Bhattacharjee J. Modulation of immune responses in stress by Yoga. Int J Yoga. 2008 Jul;1(2):45-55. doi: 10.4103/0973-6131.43541. PubMed PMID: 21829284; PubMed Central PMCID: PMC3144610.

Cortisol. (2014, February 26). In Wikipedia, The Free Encyclopedia. Retrieved 15:33, February 26, 2014, from “Cortisol.”

Muller SM, Dennis DL, Gorrow T. Emotional well-being of college students in health courses with and without an exercise component. Percept Mot Skills. 2006 Dec;103(3):717-25. PubMed PMID: 17326495.

Rao RM, Telles S, Nagendra HR, Nagarathna R, Gopinath K, Srinath S, Chandrashekara C. Effects of yoga on natural killer cell counts in early breast cancer patients undergoing conventional treatment. Comment to: recreational music-making modulates natural killer cell activity, cytokines, and mood states in corporate employees Masatada Wachi, Masahiro Koyama, Masanori Utsuyama, Barry  B. Bittman, Masanobu Kitagawa, Katsuiku Hirokawa Med Sci Monit, 2007; 13(2): CR57-70. Med Sci Monit. 2008 Feb;14(2):LE3-4. PubMed PMID: 18227770.

Qu S, Olafsrud SM, Meza-Zepeda LA, Saatcioglu F. Rapid gene expression changes in peripheral blood lymphocytes upon practice of a comprehensive yoga program. PLoS One. 2013 Apr 17;8(4):e61910. doi: 10.1371/journal.pone.0061910. Print 2013. PubMed PMID: 23613970; PubMed Central PMCID: PMC3629142.

 

Love elephant and want to go steady?

Sign up for our (curated) daily and weekly newsletters!

Editor: Jenna Penielle Lyons

Photo: Flickr user dollen