This article investigates the current literature on the link between yoga and our immune system. The result may be a bit surprising.
What is yoga?
Throughout the course of history, yoga has been praised for its wholistic approach to health, being able to affect the body and mind in a different way than traditional physical exercise. In addition to the physical postures (asana), the philosophy of yoga encourages a mindful approach to what you do; eating, walking, speaking and using your senses with purpose, being focused and observing the moment, listening to your body, your needs. Moreover, yoga is a lifestyle.
Yamas and niyamas
Yamas and niyamas offer ethical and moral guidelines to follow, such as non violence (ahimsa) and truthfulness (satya). It is all about being good to life, other people, animals and nature, as well as yourself. It might not be surprising that, yoga may boost your immune system if life follows this path. Or does it? This article investigates the current literature on the topic. The result may be a bit surprising.
Yoga is a wholistic art; it encompasses not only asanas (the physical postures), but also pranayama (breathing), mindfulness (observing the moment as it is), meditation (calming the mind to a quiet state of focus), in addition to yamas and niyamas (ethical and moral codes). No wonder why it has been known to boost the immune system.
Method of measurement
There exist various methods to measure inflammation, one popular parameter is the stress hormone Cortisol, which is an inflammatory regulator that suppresses the immune system when the body is exposed to inflammation and stress over a longer period of time. Cortisone, the synthetic version of Cortisol, is used in medicines to inhibit an inflammatory reaction.
The substance became very popular among doctors when first released on the market, however, after a while, one came to see the adverse effects it had on the immune system (Dr. Barry Sears 2011). There is found a clear correlation between being healthy, feeling well, and having low values of cortisone, moreover scientists have found that depressed-out patients have higher levels of cortisol (Thirthally et al. 2013). This knowledge has been used in studies to measure inflammation levels before and after yoga interventions. The results turn out to be inconsistent!
Looking at healthy university students, Lim et al. 2015 measured cortisol levels in a yoga group compared to an exercise group. When comparing the results, they found increased levels in both groups, indicating a negative effect of both yoga and exercise on the immune system. Other studies, on the other hand, have concluded the opposite, which is not unusual in the world of science.
West et al. 2004, for instance, measured salivary cortisol levels to compare yoga and african dancing in healthy undergraduate students. They found that the yoga group had a significant reduction in cortisol levels compared to the dance group. Brainhart et al. 1997 supports this result in their study, finding a significant reduction of plasma cortisol in their yoga group.
Other than contradictory results, the methods used in the studies above are neither ideal. Most laboratories today measure cortisol levels both in the morning and the evening to get a true picture of the endocrine status of a patient, as this very hormone fluctuates a lot during the day.
The studies assessed above have not specified in detail at what time the tests were done, except for Lim et al. who report measuring saliva cortisol between 2pm and 3pm, also one and not two times in one day. One could also look to other representative parameters of the immune system, for instance to follow the participants over a longer period of time in order to report on cases of illness (measured as both subjective parameters, but also objective such as fever, doctors declaration etc.).
No clear conclusion
In any case, the above suggests that there is need for more studies on the effect of yoga on the immune system to be able to draw a conclusion on the topic.
Meanwhile, I dare say that it won’t harm to give it a try. Many of my students have experienced a better connection to their bodies through the practice of yoga, and as a result becoming better at making decisions that are good for your mental and physical health. Yoga is, after all, so much more than what you do on the math. A yogic lifestyle, in my opinion, is way more powerful than the asana practice isolated, because it is incorporated in your every day lifestyle.