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:
Does Infrared Sauna Improve Immune System Functioning?
Let’s first consider how a far infrared sauna boosts immune system functioning. Even though some of the studies are currently carried out with traditional saunas, infrared saunas cause similar increases in body temperature, and hence, have the same effect. So let's explore some effects infrared saunas have on your immune system:
White Blood Cells
As a result of spending time in a sauna, white blood cell counts go up (12). These increases occur in different types of white blood cells, such as basophils, neutrophils, monocytes and lymphocytes, all of which have different functions inside your immune system.
These increases in white blood cell counts are different for different people. Athletes have a different white blood cell profile than non-athletes do, for instance, and see increases in their white blood cell count.
The significance of this study is demonstrating that saunas do affect immune function and that increases in different cells of that immune system are found. More specific research is still needed though, into many different cells and how they're affected by sauna usage.
Next up, another way saunas boost your immune system:
Heat Shock Proteins And Fighting Infections
Activating so-called “heat shock proteins” is another way you can boost your immune system using a sauna. Heat shock proteins are activated under different conditions, such as heat, cold, ultraviolet light exposure (which potentially gives you sunburns), and more (13; 14; 15; 16).
From an evolutionary perspective, fever is interrelated with a strong bodily response against infections. To accomplish this effect you need an increase of 2-3 degrees of core body temperature. Our True Wave II™ heaters are specifically designed to achieve a maximum increase in core body temperature while giving you an experience that is as gentle as possible. These heaters are therefore also amazing at stimulating your heat shock proteins.
Also, as a consequence of the heat shock protein response and the increase of your body temperature, you'll subsequently get a mobilisation of immune cells. These immune cells will then do their job at a site of injury or infection, and modulate inflammation in your body.
The heat shock proteins also play a role in what is called the “presentation of antigens”. These antigens can be produced by your own body or from foreign material, and lead to an antibody response as a result. In plain English, your body will be better at removing invaders.
You might think: “what do these numbers mean to me? How do I know higher white blood cell counts and heat shock protein stimulation aid my risk of disease?” Let’s explore the answer to that question:
Is A Far Infrared Sauna Good For Your Immune System? The Real-World Results
Fortunately, scientific studies exist showing real-world improvements as a result of these changes in the immune system (17; 18).
Finnish researchers looked at study participants’ sauna habits and their risk of getting pneumonia. Participants were followed over a period of 25+ years. Participants who engaged in 2 sauna sessions or more per week reduced their pneumonia risk by 21% compared to if you used a sauna once a week or less.
Also, a higher frequency of sauna bathing was protective against excess inflammation. Higher levels of inflammation increased pneumonia risk in this study, except for if you used a sauna twice a week or more.
Another study by the same research group found a general reduction in respiratory diseases as well. Compared to using 1 sauna session per week or fewer, 2-3 sessions led to a 27% reduction in respiratory disease risk, and 4 sessions or more reduced risk by 41%. Once more, study participants were followed for a 25+ year period.
These outcomes are highly significant because the earlier increases in white blood cells and activation of the heat-shock protein do lower disease risk for infections. Of course, it’s always the real-world results that you’re after, not necessarily stimulation of physiological mechanisms. In other words, stimulating physiological mechanisms, such as increasing white blood cell count, is meaningless in the absence of any real-world results such as reduced disease risk or feeling better.
Conclusion: The Future For The Relation Between Heat And Immune Function Is Bright
So, when I’m asked, “Johannes, does sauna help immune system functioning?” - I answer with a resounding “yes”. Not only have different physiological mechanisms been identified and is there an evolutionary link between your immune system and heating up your body once in a while, but real-world results are also already demonstrated too.
Still, I’d like to see far more research on this topic, such as autoimmune disease risk, immunodeficiency, genetic differences, and cancer, all in relation to the question of is a far infrared sauna good for your immune system. The future is bright though, as current research points to a promising direction…