What is cortisol?

Cortisol is often called the "stress hormone" as it is the hormone that helps the body to respond to stress ultimately affecting almost every organ and tissue in the body.  High levels of cortisol can increase blood pressure and heart rate, muscle tension, as well as disturb the digestive system causing nausea, vomiting and diarrhoea.

How is cortisol regulated?

The adrenal glands release cortisol upon stimulation by another hormone called ACTH (adrenocorticotropic hormone) ,which is produced by the pituitary gland in the brain. Additionally, ACTH is controlled by a hormone called CRH (corticotropin-releasing hormone) made in the hypothalamus which is also found in the brain. Both CRH & ACTH are affected by a negative feedback loop by the cortisol they ultimately stimulate.

Why is cortisol important?

Simply put, without cortisol we would not get up in the morning! It often gets a bad rap but not enough cortisol is worse in many respects than too much. Not enough could leave us unable to meet challenging physical tasks and completely disrupt our circadian rhythm (our natural body clock).

Cortisol Effects

Acute

• Increases hunger 
• Acute cortisol release increases stomach acid
• Increases adrenaline 
• Increases the sugar in the blood by breaking down proteins 
• Increases the body's perception of stress
• Increases sodium absorption and retention
• Reduces Calcium absorption in intestines 
• It acts as an Anti-inflammatory 
• Cause the breakdown of muscle tissue for energy
• Can both prevent sleep, cause early waking or prolong sleep (based on when or if it reaches peak levels)
• Acts to narrow blood vessels 
• Reduced Bone density by changing the activity of cells that break down bone
• Inhibits IGA (a supporting immune system element, particularly important in the gut) 
• Decreases Kidney filtration (increases probability of inflammation in the kidneys

Chronic

• Fatty acids (acute cortisol release = fat breakdown for energy but chronic cortisol release = storage of fat)
• Chronic cortisol release conditions can negatively affect the adaptivity of the immune system leading to less protection and increased inflammatory response 
• Chronic cortisol release (along with other stress hormones) shut down digestion and motility

As you can see above cortisol has a multitude of effects on the human body. high or low levels of cortisol is not enough information to determine their impact on health. A common aspect of life is that the dose makes the toxin and time is a primary factor in the response. When looking at cortisol levels it's important to look at symptoms as well as surrounding biomarkers that may interact with cortisol under different scenarios of exposure. In many contexts it is not exactly the reduction of cortisol you want to achieve but a rebalancing of this key hormone.

Key behaviours to rebalance cortisol response when dysregulation of the pathway is suspected:

• Reduce training session length  below 45 mins (longer training sessions will likely stimulate an increase in cortisol production and release. When the pathway is under strain this is often not the best idea)
• Breath work that focuses on breathing out for twice as long as your breath in - example, 3 seconds in and 6 seconds out (This type of breathing stimulates the parasympathetic arm of the nervous system and will often have a positive impact on cortisol balance)
• Specific adaptogenic herbs - example, Ashwagandha, lemon balm & the amino acid theanine (when taken as supplements can have balancing effects on cortisol even when cortisol may be low)