Cortisol, commonly called the stress hormone, is a steroid hormone that regulates many different bodily functions.
It’s produced in the adrenal glands, which are small, triangle-shaped glands that sit on top of each kidney. Cortisol levels are controlled by communication between the adrenal glands, the pituitary gland, and the hypothalamus of the brain.
Collectively, they are called the hypothalamic-pituitary-adrenal axis, or HPA axis.
While many people know cortisol for its role in the stress response, this is not its only function. Cortisol is also involved in immunity, metabolism, and blood pressure control. In fact, it can be used by almost every cell in your body.
At ZOE, we know that all bodies are different and there is no one-size-fits-all approach to being healthy. That’s why we believe in the power of personalization.
The ZOE at-home test analyzes your blood sugar and blood fat responses to food, as well as the makeup of your unique gut bugs, to give you personalized nutrition advice so you can achieve your best health.
To get started today, take our free quiz.
How cortisol relates to stress
How you react to stress, known as the fight-or-flight response, is a tool your body uses to help you survive. In a highly stressful situation, your body triggers physical changes to help you deal with danger, whether that means fighting or running away.
This was a critical survival instinct for our ancestors when dealing with life-or-death situations, like an encounter with a deadly animal.
Your heartbeat and breathing may increase, and you may begin to sweat or feel a rush of heat across your body.
When your brain senses danger or some other stressful situation, it communicates with other parts of your body to release a hormone called adrenaline. This is when the physical changes of the fight-or-flight response take place.
After adrenaline is released, your brain triggers the HPA axis, ultimately resulting in the release of cortisol.
While we rarely experience the same life-or-death situations as our ancestors, our body still reacts this way to everyday stressors, like relationship problems or financial troubles.
When short-term stress passes, cortisol levels fall, and your system returns to normal. Long-term stress, however, keeps your stress response activated and can negatively affect your health over time.
The healthy functions of cortisol
Your cortisol levels naturally fluctuate throughout the day. They are generally highest when you first wake up, and then they go back down as the day goes on.
Although cortisol is often thought of in a negative way, having the right amount is a vital part of many bodily functions, such as:
controlling blood sugar levels
influencing blood pressure
maintaining the body’s salt and water balance
The effects of too much cortisol
A healthy level of cortisol is important, but having too much can negatively affect your health. People who have cortisol levels that are too high for too long, known as Cushing’s syndrome, may have a variety of symptoms, including:
weight gain in the face, neck, or belly
high blood pressure
mood swings, anxiety, or depressive symptoms
excess body hair and irregular periods in women
low sex drive and erectile dysfunction in men
Having too much cortisol has also been associated with overall weight gain. This is because it can slow down your metabolism, increase your appetite, and change the way your body controls blood sugar.
Join our mailing list
Sign up for fresh insights into our scientific discoveries and the latest nutrition updates. No spam, just science.
The effects of too little cortisol
In the same way that having too much cortisol can damage your health, not having enough can also have negative effects, such as:
vomiting or nausea
lack of appetite and weight loss
What causes high levels of cortisol?
Elevated cortisol levels can be a result of a variety of factors.
As mentioned above, chronic stress keeps your body’s cortisol response switched on. In one small study, researchers found that participants experiencing long-term stress had higher levels of cortisol compared with those who were not experiencing chronic stress.
What you’re eating may also cause cortisol levels to rise. Although evidence is limited, cortisol levels may increase in response to certain foods, including:
caffeinated coffee without sugar
fermented milk products
What causes low levels of cortisol?
Having levels that are too low is often the result of a problem in the HPA axis.
Adrenal insufficiency is when your adrenal glands don’t make enough of certain hormones, including cortisol. Since cortisol release relies on a chain reaction along the HPA axis, any issues along the way can disrupt this process.
When the hypothalamus senses stress, it uses a hormone to signal this to the pituitary gland. The pituitary gland then produces its own hormone to communicate this to the adrenal glands, which then produce cortisol.
How can I regulate my cortisol levels?
As mentioned above, the amount of cortisol in your blood fluctuates throughout the day, but it’s highest when you first wake up.
If you’re looking to lower your cortisol levels, lifestyle changes may help. These include building a healthy gut, getting enough sleep and exercise, and supporting your mental health.
If you think you may have unhealthy cortisol levels, or if you are experiencing any symptoms of Cushing’s syndrome or adrenal insufficiency, talk to a healthcare professional. They may suggest you take a cortisol test.
Cortisol, known as the stress hormone, plays important roles in many different functions throughout the body.
In addition to the stress response, this also includes immunity, metabolism, and regulating blood sugar and blood pressure.
Healthy levels of cortisol are important, but having levels that are too high or too low can damage your health over time. If you are experiencing symptoms of unhealthy cortisol levels, talk to a healthcare professional to see if a cortisol test is right for you.
ZOE understands that there is no one-size-fits-all approach to living a healthy life. The ZOE at-home test gives you personalized information about your own food responses and gut microbiome, as well as nutrition advice tailored to what your body needs.
To get started today, take our free quiz.
Adrenal glands. (n.d.). https://www.hopkinsmedicine.org/health/conditions-and-diseases/adrenal-glands
Adrenaline. (2018). https://www.yourhormones.info/hormones/adrenaline/
Cortisol. (2019). https://www.yourhormones.info/hormones/cortisol/
Cortisol test. (2020). https://medlineplus.gov/lab-tests/cortisol-test/
Cortisol test. (n.d.) https://www.uclahealth.org/endocrine-center/cortisol-test
Cushing’s syndrome. (2018). https://www.niddk.nih.gov/health-information/endocrine-diseases/cushings-syndrome
Cushing’s syndrome/disease. (n.d.) https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments/Cushings-Disease
Definitions and facts of adrenal insufficiency and Addison’s disease. (2018). https://www.niddk.nih.gov/health-information/endocrine-diseases/adrenal-insufficiency-addisons-disease/definition-facts
Elevated hair cortisol levels in chronically stressed dementia caregivers. Psychoneuroendocrinology. (2014). https://www.sciencedirect.com/science/article/abs/pii/S0306453014001541
Health alert: adrenal crisis causes death in some people who were treated with hGH. (2021). https://www.niddk.nih.gov/health-information/endocrine-diseases/national-hormone-pituitary-program/health-alert-adrenal-crisis-causes-death-people-treated-hgh
Impact of age, sex, and body mass index on corisol secretion in 143 healthy adults. Endocrine Connections. (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597974/
Iatrogenic Cushing syndrome. (2020). https://emedicine.medscape.com/article/117365-overview
Inheritable stimulatory effects of caffeine on steroidogenic acute regulatory protein expression and cortisol production in human adrenocortical cells. Chemico-Biological Interactions. (2012). https://www.sciencedirect.com/science/article/abs/pii/S000927971100322X
The effect of diet components on the level of cortisol. European Food Research and Technology. (2016). https://link.springer.com/article/10.1007/s00217-016-2772-3
The hypothalamic-pituitary-adrenal axis: A brief history. Hormone Research in Paediatrics. (2018). https://pubmed.ncbi.nlm.nih.gov/29719288/
Understanding the stress response. (2020). https://www.health.harvard.edu/staying-healthy/understanding-the-stress-response