Got Salt? Yoga, the immune system, and the problem with some scientific studies

by Nina

Currents in Salty Water by Brad Gibson

So I’ve been seeing these articles about a particular scientific study circulating in the blogosphere that claimed the study was proof that yoga improved your immune system system. One example is from Can Yoga Boost Your Immune System? at salon.com, which claimed:

“This latest study confirms those findings, links them to the body’s immune system, and suggests this effect may be instantaneous.”

Naturally, as a dedicated yoga blogger, I decided I needed to check these articles out because I need to share the good news with our readers, too, right? But my initial readings left me scratching my head a bit (for example, “a comprehensive yoga program rapidly produces internal changes on a genetic level”), so I decided to consult with my handy scientist co-bloggers to find out more, specifically what the relationship is between changes in gene expression and the immune system.

Dr. Ram Rao put it this way:

“The article describes effects of Yoga on genes that influence the immune system. There are so many factors that affect gene expression (environment, diet, pollutants, stress etc) and so the authors looked to see if Yoga did the same.”

That makes sense, right? So far, so good. But Dr. Brad Gibson said it this way:

OK, what they were measuring was gene expression profile changes in PBMC.

"Right before and after each regimen, 20 ml blood was drawn, PBMCs were immediately isolated, total RNA was recovered and used in gene expression profiling experiments interrogating >47,000 independent transcripts in two hybridization runs"

First, PBMCS (according to Wikepedia) are "peripheral blood mononuclear cell (PBMC) is any blood cell having a round nucleus. For example: a lymphocyte, a monocyte or a macrophage. These blood cells are a critical component in the immune system to fight infection and adapt to intruders."

So, what they are suggesting is that the observed changes in the gene expression profiles in blood immune cells (PBMCs) in Yoga practioners is correlated with an improved immune function. However the second bit is pure speculation.  They see a change, but it's anybody's guess if this represents a better or healthy immune system.  They provide some guesses, but….

Okay, I admit it, that phrase “the second bit is pure speculation” was a bit disappointing. I’d just wasted my time (and theirs) on an idea for a blog post that I couldn’t really use because, after all, on this blog anyway, we try to back up our claims with good science. But a few days later I realized I actually had more of a contribution to make on the topic than some of the other blogs because while everyone else was simply parroting some kind of good news about yoga they didn’t really understand, I had an actual real-life scientist weighing in on the significance of the study and he said to take it with a giant BUCKET OF SALT.

However, before writing the post, I decided to do a bit more research by looking an the original scientific journal article that everyone was quoting from Rapid Gene Expression Changes in Peripheral Blood Lymphocytes upon Practice of a Comprehensive Yoga Program—you know, just in case. And here is the abstract from the study:

One of the most common integrative medicine (IM) modalities is yoga and related practices. Previous work has shown that yoga may improve wellness in healthy people and have benefits for patients. However, the mechanisms of how yoga may positively affect the mind-body system are largely unknown. Here we have assessed possible rapid changes in global gene expression profiles in the peripheral blood mononuclear cells (PBMCs) in healthy people that practiced either a comprehensive yoga program or a control regimen. The experimental sessions included gentle yoga postures, breathing exercises, and meditation (Sudarshan Kriya and Related Practices – SK&P) compared with a control regimen of a nature walk and listening to relaxing music. We show that the SK&P program has a rapid and significantly greater effect on gene expression in PBMCs compared with the control regimen. These data suggest that yoga and related practices result in rapid gene expression alterations which may be the basis for their longer term cell biological and higher level health effects.

Whoa, I’m thought, somehow we went straight from “wellness” and “benefits” to specific claims about the immune system. Then there were all those vague words like “suggest” and “may.” But, of course, I’m not scientist, so again, I consulted with Brad. Here is what he said: 

Look at their last sentence:
"These data suggest that yoga and related practices result in rapid gene expression alterations which may be the basis for their longer term cell biological and higher level health effects."

That is, they don't know whether the change in gene expression patterns they observed has anything to do with the yoga practice, let alone a more healthy immune system.  This is a general problem of small correlative studies of this type.  At best I would say this is an intriguing pilot study (low N, not really statistically significant enough to establish even correlation), which will need considerably more work to establish:
(1)  'causation' (i.e., yoga practice causes these genetic expression changes as opposed to some random or other variable that wasn't accounted for)
(2) 'benefit' (the expression changes that are observed are actually beneficial and lead to an improved immune system)
(3) 'mechanism' (why these gene changes lead to a more healthy or robust immune system).

My translation? The number studied was so low that correlation couldn’t be established. Causation definitely was not established. And then there was a bunch of speculation. So, yes, get out the salt everyone, and sprinkle liberally! (For you non-American readers out there, we have an expression “take it with a grain of salt” that means you should be skeptical about something. So I like to joke about buckets of salt, when I think a lot of skepticism is warranted. And, as much as we love yoga, this is not the first time we’ve looked at scientific studies of yoga that indeed warrant quite a bit of skepticism.)

Note: I’m pretty sure that yoga is good for the immune system, however. Stress compromises the immune system—this is known medical fact—and yoga reduces stress. Spending more time in Rest and Digest mode (where your body restores itself) rather than Fight or Flight mode (where your body depletes itself) is therefore good for your immune system.

New Study Supports Our Personal Bias! Yoga is Good for Older Adults!

by Baxter

Baxter in My Yoga Room by Nina Zolotow

One of the benefits of our blog is that we get to keep up on all the latest developments in research on yoga and aging. Just the other day, Nina came across an abstract from the National Institutes of Health that piqued my fancy, which was titled “The effects of yoga on physical functioning and health related quality of life in older adults: a systematic review and meta-analysis.” Man, is that a mouthful! What the authors were interested in finding out was how yoga compared to other forms of physical activity. Well, let me have them tell you what their goal was:

“The goal was to review systematically the comparative effectiveness of yoga, compared with other exercise interventions, for older adults as shown on measures of health and physical functioning.”

Okay, so once again, researchers are limiting their look at yoga to the physical level of yoga asana, but to me, any advancement in acknowledging the benefits of yoga for aging is a step in the right direction.

So, how did they go about figuring out the answer to their question? Well, they scoured the studies that had already been done; in other words, they looked back to see what other folks had already done, instead of designing a new study of their own from scratch. This can be a helpful way of answering some questions, especially if you can find enough studies out there that meet your criterion to include in your analysis. In this case, they looked for studies published in English, done between 1950 and 2010, which were a certain kind of study that is considered more objective, and they looked in a variety of sources, including ones like PubMed. When all was sifted through, they found 18 studies that qualified and met their specific standards.

What their analysis of the data from these 18 studies yielded sounds pretty promising, with a few caveats where either the data was not so strong or just didn’t support yoga helping at all, like with cognitive issues such as Alzheimer’s Disease. Here’s what they found:

“[our analysis] suggested that the benefits of yoga may exceed (emphasis is mine) those of conventional exercise interventions for self-rated health status, aerobic fitness, and strength. However, the effect sizes were modest, and the evidence was mixed for yoga's effect on depression, sleep, and bone-mineral density. Studies did not find an effect on cognition.” 

As is almost always to case, they go on to say that while these findings are encouraging, what is needed is more studies, well-designed, with a lot more participants involved. Good news for future yoga therapists wanting to do research, but mixed news for the rest of us. But again, overall, any news like this is encouraging for those of us doing yoga regularly that our efforts do bear some good fruit. Perfect timing for this harvest season! And if we are lucky, Brad might lend us his scientific take on this study in a future post.

To read the abstract in its entirety, see here.