How can cold water strengthen my immune system?
This particular health benefit claim may have been popularised by a 2016 Dutch study where users of daily cold showers showed a reduction in self-reported sickness [1]. Since then, there have been numerous studies showing that cold exposure, typically in winter ice swimmers, increases the plasma levels of a number of different immune cells [2]. Quite simply, more immune cells in your blood is generally a good thing.
A study comparing regular winter swimmers who practiced more than once per week to non-habitual swimmers showed that resting concentrations of some white blood cells such as leukocytes and monocytes were higher compared to the non-habitual swimmers [3]. Another study found regular winter swimming may decrease respiratory tract infections by 40 percent [4]. These studies bolster all those anecdotal claims shared among communities of winter swimmers and cold water enthusiasts that they experience fewer colds and influenza.
The benefits around winter (ice) swimming with temperature in waters below 5°c are perhaps the most numerous and therefore the most cited, and where plasma (blood) levels have been measured objectively. The benefits of ice water exposure correlate to better immune health and perhaps with the added benefit of the cold exposure being undertaken in nature. Who knows the importance of the ‘nature’ aspect until detailed studies are explored - but we shouldn’t overlook it: whenever it’s safe - nature is best.
DCE boost the immune system.
We know that cold water exposure appears to boost certain populations of immune cells. When healthy young men were exposed to cold multiple times over a period of six weeks, their CD25 lymphocytes increased after three weeks, while CD14 monocytes increased after six weeks. This is another indicator that the benefits derived from the adaptation that occurs in the body come from repeated exposure, not from the very occasional dip or cold shower.[4] This isn’t a surprise when we all know that doing the odd set of press-ups doesn’t make us fit.
Another study demonstrated that cold exposure increased the numbers of white blood cells, specifically a specialised type of immune cell that can kill cancer cells. The white cell counts remained elevated for two hours after cold exposure. The participants’ natural killer cells (white blood cells of the innate immune system) also increased [5], a separate study noted similar findings [6].
Immune Strengthening and the Wim Hof Method
Wim Hof and the Wim Hof Method (WHM) are perhaps now increasingly cited in terms of pushing the boundaries of our innate ability to control our immune system, something previously understood to be autonomic, beyond our control [7]. WHM combines DCE with breathwork and mindset training. In the most famous study of the WHM, subjects who trained for only 4 days were able to suppress their primary (innate) immune response to a bacterial endotoxin that was injected directly into their bodies. Should the WHM be of interest to you? Hell yes! [8].
If you want to stock up on plasma immune cells then cold exposure is certainly worth looking into. If you want to go much further into suppressing inflammation, strengthening immune response and managing autoimmune response then the WHM (cold and breath work) is worth exploring.
References
- Cold showering and sickness: https://journals.plos.org/plosone/article?id=10.1371/ journal.pone.0161749
- Winter (ice) swimming and health, a review: https://www.ncbi.nlm.nih.gov/pmc/articles/ PMC7730683/
- https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2281.2000.00235.x
- https://www.sciencedirect.com/science/article/abs/pii/ S0306987703002706?via%3Dihub
- https://link.springer.com/article/10.1007/BF00242274
- Activation of NK cells: https://www.liebertpub.com/doi/10.1089/jir.1988.8.393
- Wim Hof, regulation of autonomic function during cold exposure: https://pubmed.ncbi. nlm.nih.gov/29438845/
- Wim Hof Method: https://www.wimhofmethod.com/practice-the-method
