Does sauna improve immune system functioning? In this blog post, I’ll first consider some of the basics of immune system functioning and explain why regulating body temperature has an evolutionary link to how well your immune system functions.
Then, I show that by increasing your body temperature with an infrared sauna you affect the immune system at several levels, such as increasing white blood cell count and affecting what are called “heat shock proteins”. Lastly, I demonstrate that these outcomes translate into real-world results, such as a huge overall lower respiratory disease risk, including pneumonia.
Let's begin with the basics though:
Immune System Basics And Its Tight Relation To Thermoregulation
Before talking about the relationship between the immune system and thermoregulation, let’s first consider some basics of that immune system:
Just like your brain, your immune system expresses a certain “intelligence”. For instance, you’ve got parts of the immune system that are quicker acting, called the “innate immune system”, and parts that are slower and more deliberate, called “adaptive immunity” (1; 2).
And, also just like your brain, your immune system engages in memory, learning and adaptation, while many different parts of the immune system are interacting with each other. And just like you’ve got many different brain areas and subdivisions therein, the same is true once again for the immune system.
Here are some examples:
You’ve got dendritic cells, natural killer cells, macrophages, and different types of T-cells. All of these cells have their own roles and also work together for immune function to work well. The broader goal of the immune system is to defend you, as an organism, against substances that are not you or a threat to you.
Harmful bacteria or viruses are an example of an invader that is not you, and a collection of cells that goes haywire and becomes cancerous is an example of you but still a threat to you and your health. Both of these problems are aimed to be eliminated by the immune system.
Throughout millions of years of evolution, that immune system has developed in interaction with the environment. Millions of years ago, primates evolved into the first humans in a very specific environment. Not did the ancestors interact with the environment through the consumption of many different plants and animals and defend themselves against pathogens, but the nature of the environment itself also played a major role.
For instance, thermoregulation was essential to survive. And, thermoregulation - so dealing with (extreme) cold and hotness - still affects the immune system and all of its other tasks in you and me to this day. For instance, extreme heat still affects inflammation levels, which in turn influence both your risk of getting a clinical depression and immune system functioning at many different levels.
However, our current living environment - with 24/7 food availability, no necessity to move, and stable temperatures - isn’t great for optimal immune system functioning.
Hence, if you don’t move and exercise, your immune system won’t function properly (3; 4; 5). The same is true for undereating or overeating, or eating the wrong foods - the immune system won’t function properly (6; 7; 8; 9). Brown and beige fat, which is built through cold exposure, is similar (10; 11; 12).
Hence, certain preconditions in both the living environment and the interaction with it exist for optimal human immune function. Heat is similar, and therefore, I’ll explore that dynamic in more detail right now: