EARLY last year we travelled to the icy mountains of Poland as part of an unusual experiment. A group of volunteers that we had recruited spent the next four days immersing themselves in freezing-cold water, lying in snow or hiking up a mountain wearing just shorts in temperatures as low as -27 °C. We were hoping these volunteers might shed new light on the workings of the immune system.
Our immune system is vital for protection against invaders such as bacteria and viruses, and without it we would be quickly overcome. But there is another side to this story: many conditions are caused by the immune system kicking in when it shouldn’t, attacking components of our bodies. These autoimmune disorders include rheumatoid arthritis, multiple sclerosis and type 1 diabetes, with alone. If there was a way to control our immune reactions without drugs, the benefits would be huge. Even better, what if we could consciously control our immune system?
At first this seems a ridiculous idea, because our body’s innate immune system has long been known to operate in an autonomic fashion: we can’t voluntarily control it. But what if this understanding was wrong?
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, certainly thinks so. Hof holds several world records for withstanding extreme cold, such as immersion in ice for almost 2 hours. Over the years, he developed techniques that allowed him to withstand low temperatures. These include meditation, breathing methods and repeated exposure to cold. But he also made the outlandish claim that he could exert control over his immune system. In 2011, although we were sceptical, we put Hof’s claim to the test.
“He made the outlandish claim he could exert control over his immune system”
In our department at Radboud University Medical Centre in the Netherlands, we have an experimental model set up to test the human immune system. We used this for many years to trial potential new drugs for inflammatory conditions such as sepsis. The model involves injecting healthy volunteers with a substance called endotoxin (found in the cell walls of bacteria), which tricks the immune system into reacting as if there are bacteria in the bloodstream that need to be eradicated. In response to this “infection”, the body mounts an immune response, producing signalling molecules called cytokines and inducing flu-like symptoms and fever. This response only lasts a few hours and is not harmful, aside from feelings of illness. We used this set-up to test Hof’s claim.
To our surprise, levels of the stress hormone adrenaline – the molecule produced in a “fight or flight” response by the sympathetic nervous system – increased rapidly to a high amount after Hof started practising his breathing techniques. Hof also reported almost no flu-like symptoms after being injected with endotoxin and the levels of cytokines in his blood were less than half those of a control group of healthy volunteers.
How could we make sense of this finding? It has been known for several decades that stress hormones like adrenaline can suppress the immune response, so Hof appeared to be able to subdue his by consciously activating his sympathetic nervous system (SNS). This was a remarkable finding, because the SNS is part of the body’s autonomic nervous system and, as its name suggests, was not thought able to be voluntarily influenced. But to provide proper proof of this discovery, we needed to conduct a larger study with two groups of subjects, one practising Hof’s techniques and the other serving as a control group. That is where Hof’s second claim came into play: that he is not unique and can teach his technique to anyone.
This is how in winter last year we ended up in Poland, where 12 healthy volunteers were trained in Hof’s techniques. As well as showing them his cold-exposure methods, Hof taught them his meditation and breathing techniques, which involve hyperventilation and then holding one’s breath. Witnessing the training baffled us, because we did not expect all the volunteers to be able to complete this challenging programme. But, motivated by Hof’s leadership, they did.
When we got back to the Netherlands, we tested the volunteers’ immune responses using the endotoxin model. : the volunteers trained by Hof, who practised the breathing techniques during the experiment, showed exceptionally high adrenaline levels – even higher than those measured in people bungee jumping for the first time (PNAS, vol 111, p 7379). They also reported fewer flu-like symptoms, experienced lower fevers and had cytokine levels of less than half those of the control group. These results show, for the first time, that it is indeed possible to voluntarily influence the SNS and hence the innate immune system.
What does this mean for people with autoimmune diseases? Although the possibility of keeping our immune system in check without medication is a new and promising concept, there are many questions that need to be answered before this method could be used on people with such illnesses. For instance, which of Hof’s three techniques is responsible for the profound suppression of the immune system observed? Are all three needed? It would make the process more feasible if people only needed to learn and practise one or two of the techniques. Also, our results came from studying healthy volunteers, so at this stage we do not know whether practising these techniques is feasible for people with autoimmune diseases.
We aim to dig further into this area in the next few years, evaluating the most effective parts of Hof’s techniques for people with rheumatoid arthritis to see whether they are truly effective in such a chronic inflammatory condition. The prospect of one day being able to manage autoimmune diseases without the use of drugs certainly warrants a closer look.
Read more: “Three ways the iceman controls his immune system“
This article appeared in print under the headline “Just chilling out”
