Close-up on… chronic stress
Cardiovascular Function and Salt
The stress hormone cortisol helps to regulate the balance of salt and
water in our body. This is essential because too much or too little
salt can affect the normal functioning of our heart. The electrical
currents that stimulate our heartbeat and the functioning of our heart
are highly dependent upon salt (sodium) levels.
You have surely noticed that your sweat is a little salty. We lose
salt when we sweat. This is his why drinks like Gatorade® have salt in
them. If our sodium levels become too low, then cortisol stimulates a
craving for salt.
i.e.: Pizza after moving day really hits the spot!
Cardiovascular Function and Water
Our body is mostly made of water; the range is between 55% in women
to 65% water in men. Our blood is fluid because of this water content.
The amount of water present contributes to what is known as blood
Blood volume is directly related to blood pressure. Higher blood
volume means higher blood pressure. A lot of water makes the heart work
harder. This is why certain blood pressure medications (e.g. diuretics)
are designed to reduce the amount of water in the system. Less water
means lower blood pressure.
TAKE HOME MESSAGE
A big problem in today’s world is that we often do not use up the energy
we consume. When we were mammoth hunters, we ran like crazy and used up
the energy. But today, the stress response system secretes stress
hormones when we are stuck in traffic or sitting at our desk at work. Why do we speak about mammoth hunters?
If everyday levels of stress hormones are high then the delicate
salt/water balance that keeps our heart working normally can be
disrupted. In the long-run, this can lead to cardiovascular disease.
Stress can also indirectly lead to high cholesterol levels. Repeated exposure to stress often leads to unhealthy lifestyles.
i.e.: Eating a diet high in saturated fats, weight gain, increased tobacco and alcohol intake, and decreased physical activity.
These habits all raise the levels of low density lipoprotein (LDL),
or bad cholesterol and decrease levels of high density lipoprotein
(HDL), or good cholesterol. But lifestyle alone does not explain the
The stress hormone cortisol has to be made or synthesized. The first
ingredient of cortisol is cholesterol. When exposed to chronic stress,
cholesterol levels increase to make more cortisol. But not all
cholesterol becomes cortisol! People at risk of developing high
cholesterol (e.g. family history) with unhealthy lifestyle and who are
chronically stressed are at greatest risk of health problems.
Insulin Resistance and Type II Diabetes
Insulin is a hormone that carries a message that lowers blood sugar levels and helps us to store energy for future use.
The receivers of messages in our body are called receptors. In type
II diabetes, the message carried by insulin is not understood by the
receptors and blood sugar levels remain high.
Normally, when cortisol levels rise, insulin secretion stops. After
all, we need all the energy we can get! Sugar fuels our muscles and
brain. So with lower levels of insulin, blood sugar levels can remain
high enough to provide us with the energy we need. Our stress response
system has a fail-safe just in case we still have insulin kicking
around. Stress hormones make sure that our cells do not respond to any
remaining insulin in our system.
If we are chronically stressed, then our insulin levels can remain
low and our blood sugar levels can remain high. On top of that, our
cells can become almost totally resistant to insulin.
Cortisol first and foremost maintains energy balance. When we expend
energy (i.e. use up calories), our body needs to replace the energy
lost. Cortisol carries this message: refuel!
Now, the brain and cortisol are always out to protect us. When we are
chronically stressed they will ‘help us out’ by making it easier to get
at our stored fuel (i.e. our fat tissue). So they begin storing energy
in easy-access areas, such as our gut or trunk. The end result is truncal obesity or fat around our midsection.
The unfortunate thing is that our brain and stress response system do
not know the difference and take for granted that we have used up the
energy. Our brains have not changed much since we were hunter-gathers
chasing mammoths, so we react similarly to the stressors of the modern
These are but a few examples of how stress hormones are vital to our
health. The take home message here is that our body and brain maintain
their normal functioning (homeostasis) through the delicate and precise interactions between many systems.
The stress response system and its end product cortisol are key
players in these interactions. When the cortisol system becomes
deregulated, it affects all other systems that depend on its integrity