Strengthening the immune system has become an important focus for many people these days. In the current global pandemic, many are rightly asking themselves how they can build up their resistance to pathogens. They have no wish to face the looming danger passively and helplessly but wish instead to take active steps to ward off the danger themselves. Self-efficacy is a healthy and effective solution.
Sadly, one specific and relatively simple way of strengthening the immune defences has been largely ignored in favour of other options. Why has it still not caught on everywhere? Use your breathing!
BREATHING AS A DIRECT PATH TO THE IMMUNE SYSTEM
But perhaps this is overstating the case. In recent years in particular, certain breathing techniques (notably the Wim Hof breathing technique) and new knowledge about paths and strategies to healthy breathing have become more widespread. Quite rightly in my opinion, and I dare to predict that this is just the beginning. Following a wave of knowledge about meditation, mindfulness, stress reduction and the importance of an individualised, healthy diet and optimal sleep, one of our essential basic functions – our breathing – is now being accorded the importance it deserves. If, on the one hand, it is true that new findings about breathing have recently come to light as a result of much research, on the other hand, it is also true that there are some that are anything but new. Rather, they have been rediscovered – locked away in a drawer for some inexplicable reason. Old knowledge about breathing.
THE WIM HOF METHOD IN THE SCIENTIFIC SPOTLIGHT
In January 2014, an article was published in the renowned PNAS Journal [Proceedings of the National Academy of Sciences of the United States of America] under the title “Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans” . This study is based on a single case study of the Dutchman Wim Hof . This man has broken over 20 world records for cold endurance and has very successfully spread his very own method, the Wim Hof method, around the world. At that time, Wim Hof was still relatively unknown and was “The Iceman” just in Holland itself – mad and mocked. A few years after the study on Wim Hof by Dutch doctors at the Radboud University Medical Centre in Nimwegen, the results of which were published as a single case study, the same doctors conducted a second study but this time with a group of young people, who were then compared with a control group. Normally, the fundamental purpose of the work of this group is to find appropriate measures and mechanisms of action to counter the increasing incidence of sepsis. Both the study on Wim Hof himself and the group study published in PNAS investigated the human immune response to injections of lipopolysaccharides (LPS). LPS are found in the outer membrane of Gram-negative bacteria. They are released when the microorganisms die. They act in the host as endotoxins and induce inter alia the release of IL-1 and TNF-α by macrophages. This is a process that can be relatively easily monitored, and which allows investigators to, as it were, watch the immune system in action by taking regular blood samples during the first 4 – 6 hours after the endotoxin injection.
The 2014 study showed that it is possible to modulate the immune system with something as simple as a breathing technique, the result in this case being that there were hardly any reports of the otherwise observed severe malaise from the study subjects who had trained in the Wim Hof method for just 10 days. Objective parameters showed a marked difference in the cytokine levels in the two groups. In those who had received training, there was a dramatic increase in IL-10 following LPS administration, which correlated with an increase in adrenaline. Pro-inflammatory mediators such as IL-6, IL-8 and TNF-α were lower in number and correlated with IL-10. The sympathetic nervous system was activated by this method of breathing, resulting in an increase in adrenaline* but without any corresponding increase in noradrenaline and cortisol. The breathing method is no secret and can be learnt from the many instruction videos now available . The results generated a great deal of interest, and several renowned universities are now studying the Wim Hof method. Shortly after the publication of the results, an incredibly positive and informative article appeared in Nature, which optimistically concluded that we were well on the way to finding the connection between the immune response and neutral regulation . To have an idea of how the study subjects breathed following endotoxin administration, the following video from the additional files in the journal provide fascinating footage . The researchers themselves were extremely sceptical and reluctant at first. The first author Matthijs Kox told me in an interview that Wim Hof had come to them himself, claiming that he knew a way of influencing the autonomic system and thus also his immune response . This was considered medically impossible. Now, scientists are starting to think otherwise. Over-inflated expectations and hypercritical reporting aside, the essence and applicability of breathing techniques will become apparent in the future.
Several other studies on the Wim Hof method have been published since the PNAS study in 2014, but all with a different focus. For example, researchers at the University of Michigan in Detroit studied Wim Hof using fMRI (functional magnetic resonance imaging) and PET (positron emission tomography) to examine the metabolic and neural links to cold . The study of the Dutch group published in 2019 showed a significant fall in the ESR (erythrocyte sedimentation rate) in patients with the chronic autoimmune disease axial spondyloarthritis following an 8-week intervention (Wim Hof method) .
BE SELECTIVE IN THE USE OF ADRENALINE
It is very often incomprehensible to many why activation of the sympathetic nervous system and modulation of the immune system should be something positive. In many cases that is not necessarily true, this being the case when it is not just short-term but becomes chronic, such as in permanent stress. On the other hand, as Matthijs Kox pointed out to me, activation of the sympathetic nervous system and the corresponding increase in adrenaline levels are desirable in autoimmune disease. Adrenaline appears to have acquired a bad reputation. This is completely unjustified, as adrenaline is very beneficial for the function of the immune system. In this context it is helpful to refer to McEwen’s model of allostatic load . It describes the effect of overload after repeated and chronic exposure to stress. To put it very simply and briefly, our brain is constantly seeking to predict future events. To regulate to some degree the uncertainty of life, we scan our environment and continuously make predictions about changes to our environment and their effect on us. We feel secure in a predictable environment. On the other hand, if we find ourselves in an environment that constantly threatens us and in which we must always be on our guard, we are in a permanent state of stress. We are constantly trying, and above all expending much energy in doing so, to act predictively and to minimise the risk of any unpleasant surprises. And this is precisely what is associated with an increased allostatic load, which in the long term ultimately turns initially helpful short-term adjustment processes into the exact opposite. We pay for the chronic activation of neuroendocrine, cardiovascular and emotional alarm systems with pathophysiological changes.
But let us now turn back to short-term activation of the sympathetic nervous system. When we use the opportunity to increase adrenaline levels in the short term, our stress and immune systems are activated, and this is associated with two crucial factors: firstly, the activation is not prolonged but limited to a short period of time and secondly, our state of mind is playful, curious and relaxed, but not characterised by helplessness or anxiety. Breathing techniques that can trigger these effects can thus be used to control stress and be beneficial for oneself and one’s immune system. It remains to be seen to what extent these techniques are a specific or just one possible path to strengthening the immune system (alongside, for example, controlled states of stress such as sport, ice baths and sauna).
CONCLUSION: ADRENALINE AND LEARNING
It may be a surprise to learn that these short-term positive effects can even directly result in improved learning and memory consolidation. For both factual memory and in sport the all-important motor memory, specific activation of the sympathetic nervous system at the end of a learning unit, or more precisely an increase in adrenaline levels induced by breathing techniques or other paths, results in a marked improvement in mnestic retention. A further important point is that regular activation of adrenaline while in a calm state of mind helps strengthen both. This means that in situations that are stressful and likely to be beyond our control, as is certainly the case in many competitive situations in sport, we are more likely to achieve a trained mental balance and to possess, despite the activation of the sympathetic nervous system, more cognitive and emotional capacity to manage the situations to our advantage. Short-term stress training therefore has effects that transfer to areas that cannot be fully controlled.
*The terms adrenaline and epinephrine are synonymous. There is an incredibly interesting scientific story behind the two terms, with partly racist aspects. For more information, see Brian B. Hoffman: “Adrenaline”, Harvard University Press, Cambridge and London 2013.
 B.S. McEwen, E. Stellar: Stress and the individual. Mechanisms leading to disease.. In: Archives of Internal Medicine. 153, Nr. 18, 27. September 1993, S. 2093 – 101.