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Stress and Immunity

The power of stress has been barely understood since Hungarian-Canadian researcher Hans Selye first put out his General Adaptation theory in 1936.

Selye broke down the idea of stress into two categories: Eustress (eu as in euphoria) and Distress. Both are energy outputs, but we see them in terms of positive and negative experiences. Getting married and getting divorced are measured as the same amounts of stress. Giving birth and losing someone to the grave, equally. These are extreme examples, but one may be said to be eustress, while the other creates great distress. In each of these cases, it takes a couple of years to adjust to the changes.

The body’s reaction to both types is similar. The greater the stressor, the more energy it requires from the body, whether we perceive it as positive or negative.

Selye focused on the HPA axis (hypothalamus-pituitary-adrenal), which prepares the body to mount a stress response, ready for the fight or flight. This is still unknown in some quarters. We generally only hear about the HPA axis from Naturopathic doctors, instead of having it understood in the main stream.

In Selye’s theory, he gave rise to the idea that chronic stress creates a state where we attempt to handle the stress over long periods. He called this the General Adaptation Syndrome, or GAS. This adaptation is a biological response to stress and has three stages: alarm, adaptation and exhaustion.


In the alarm stage, the body jumps into action to help us fight off an attacker. Cortisol and adrenalin are released into the blood stream. We get a load of sugar to the blood, cortisol to lubricate the joints, adrenalin to give us a boost of energy. The lungs dilate to help us breathe deeper, the heart speeds up and blood pressure rises.

We can imagine that this is the best preparation to run away from the tiger. But as it goes on, it is no longer a healthy response. The body begins to realize that the danger is not the emergency we imagined and things settle down a bit. But just a bit.


Also called the resistance phase, this is a time when the body is still on alert, because it realizes that the danger has not truly passed. Things do settle down a bit, but the blood pressure tends to stay a little high, heart rate may be faster than necessary, as we enter a state of watching and waiting. All of this puts a strain on the arteries. The breathing is still not at a level of deep meditation or relaxation and we may have trouble sleeping. Adrenalin and cortisol are still circulating unncessarily.

When we are in fight or flight, much of the body’s resources are diverted to the emergency and away from healing and restoration. This means that all of our usual functions are ranked in second place, so that we can pay attention to the emergency. Energy for anything we don’t need for general health gets diverted to the red alert. This includes digestion, reproduction, sleep and relaxation, kidney function and deeper levels of creativity and thought, so the brain also starves.


In this final phase, the body has given its all and still the stress remains. It creeps up again and looks remarkably similar to the alarm stage, but at this point, the body has run out of reserves. The energy it takes to maintain a constant state of alarm is extremely costly to our personal resources. Once they begin to exhaust, we are in danger of losing strength from all other areas of the body

This is how we come to understand the effect of stress on our immunity. Ongoing, unremitting stress will take our immune system down until we are unable to resist organisms that we would normally handle easily. The entire body is sapped of energy when we have ongoing stress. There are no resources left when an infection or disease comes to call.

In the recent history of germ theory there were two camps, headed by scientists Louis Pasteur and Claude Bernard. Pasteur said, “Oh my god, there are germs all around us; we have to kill them all”. Bernard said, “Oh my god, there are germs all around us; we have to make sure the terrain (‘milieu interieur’) of the body is strong so it can resist and overcome them.” Bernard laid the groundwork for the idea of homeostasis, in which the body seeks always to balance itself and its environment.

Resilient Immunity

Why do some people get sick (for example, with a flu that might be circulating over a winter), while others do not? Simple answers include dosage (to what extent were you exposed?) and resilience (how strong are you to fight it off?). Our vitality and available resources both help to determine how well we can fight off an invader.

The immune system’s education also helps. This entails how experienced the body is with a particular virus or strain. Every time we fight something off, the body remembers it, as we discussed in our three immune response blogs. If the body is resilient, has resources, and recognizes the invader (meaning we have built the necessary B and T cells), we may just feel tired for a few days, rather than actually getting sick. If it has to mount a full response, we will have all of the symptoms, including fever which is often the tip off that we are sick.

In either case we are quite capable of dealing with these germs. Yes, there are deadly diseases out there, but with modern conditions in the Western World, we have good sanitation, decent and plentiful food and clean water, all of which are necessary for general health. As we look into history at the great epidemics, we do well to remember that their living conditions and stress levels were quite different from ours.

One of the reasons, I believe, that people suffered so greatly in the flu pandemic of 1918, is that the world was exhausted by war and by the idea of a world war. It must have seemed as though the entire planet had gone mad, and the resulting distress lingered long after it was over.

This was declared the war to end all wars. Fat chance. But imagine the atmosphere at that time. All available food, clothing and mineral resources, including millions of horses were spent on this foolish endeavour, sapping communities and economies of their general health, wealth and transport, and creating an even more terrible isolation than we are feeling now. It’s no wonder people fell so sick so readily.

As we consider the continuing news cycle during this current pandemic, please think about your stress levels and how to keep them level. Your immune system depends on this for its ability to fight off the infection if it comes to you. Watch the numbers that are published rather than listening to the media report on them.

Here in Ontario, check our raw case data.

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