Does yoga practice improve the immune system?
We have all heard about the many positive health effects of a regular yoga practice. But can it actual improve our immune system? Fellow Yogi and Anatomist on my Yoga Teacher Training Course David Keil looks in detail at this very question.
Both acute and low-intensity chronic stressors can trigger a response from our immune system, which can include inflammatory responses in the body. Markers of our immune system responding to a stressor can include the presence of certain chemicals called cytokines, which are part of our body’s inflammatory response, as well as endothelial microparticles. Experiencing an immune system response to a stressor can also change our immune cell counts, antibody responses, and our gene expression in immune cells.
There have been multiple clinical trials which have evaluated the effects of yoga on one or more specific measures of immune system function. The research study that we summarize in this article conducted a review of all of those previously published studies to see if there were commonalities among them. This kind of study, a systematic review of many smaller published studies, can help highlight important findings that might not show up in the same way if we were looking at the results of only one study at a time.
The research team searched science databases, PubMed, Web of Science, and PsycINFO, for relevant randomized control trial type studies that examined the effects of yoga on the immune system. They found 15 studies that fit their criteria for inclusion in their review. The research team reviewed each of these individual studies for yoga treatment used and specific effects on immune system function.
Each of the individual studies that they reviewed for their larger study varied considerably in the yoga treatment that was used. Yoga practice time in each of the individual studies varied from 30 to 90 minutes. Practice frequency varied from once per week to daily. The duration of each study varied from one to six months. Style of yoga also varied between studies. Immune system response markers that were measured included: the presence of particular cytokines, CRP, and endothelial microparticles. (Cytokines, CRP, and endothelial microparticles are all pro-inflammatory markers; they’re compounds in the body that are present when the immune system is triggered by a stressor of some kind.) Some studies also measured immune cell counts, antibody responses, and gene expression markers in immune cells.
Multiple studies that were examined in the larger review study reported that a pro-inflammatory immune system marker, IL-1beta, was reduced in the yoga treatment groups. Two other pro-inflammatory immune system markers, IL-6 and TNF-alpha, decreased in yoga treatment groups in some studies, but were not affected in others.
More generally, these results suggest that yoga contributes to down-regulating several pro-inflammatory markers, resulting in the reduction of certain compounds in the body which are produced when the immune system is triggered by a stressor of some kind. No study in this review reported any negative effects of yoga on immune system markers. No study reported either increased pro-inflammatory markers or decreased anti-inflammatory markers.
Why is this relevant to yoga practitioners?
The most current research is suggesting that yoga may potentially provide a number of health benefits beyond just increased strength and flexibility. What is often unclear, due to the nature of doing clinical-type research, is what yoga treatment specifically is necessary to experience these benefits. Review papers such as this one are helpful because they can bring our attention to the commonalities between individual studies and inform us of which aspects of a yoga treatment seem necessary to experience a particular benefit. In this case, it doesn’t appear that the length of an individual practice session or style of yoga, for example, impacted whether or not yoga positively affected the immune system.
The authors of this review do point out in their discussion, however, that the duration of all studies included in their review was fairly short, six months at the longest. They note that two studies of a different type, which could not be included in their review, found that yoga practitioners who had practiced for at least two or at least five years had lower levels of some pro-inflammatory markers than yoga practitioners who were new to yoga at the time of those studies. This suggests that while yoga may indeed improve immune system function, it may also take some time, potentially years, to experience that benefit.