Cortisol, a glucocorticoid (steroid hormone), is produced from cholesterol in the two adrenal glands located on top of each kidney. It is normally released in response to events and circumstances such as waking up in the morning, exercising, and acute stress. Cortisol’s far-reaching, systemic effects play many roles in the body’s effort to carry out its processes and maintain homeostasis.
When chronically elevated, cortisol can have deleterious effects on weight, immune function, and chronic disease risk.
Cortisol (along with its partner epinephrine) is best known for its involvement in the “fight-or-flight” response and temporary increase in energy production, at the expense of processes that are not required for immediate survival.
Blood Sugar Imbalance and Diabetes
Under stressful conditions, cortisol provides the body with glucose This energy can help an individual fight or flee a stressor. However, elevated cortisol over the long term consistently produces glucose, leading to increased blood sugar levels.
Cortisol blocks the effect of insulin—essentially rendering the cells insulin resistant—the body remains in a general insulin-resistant state when cortisol levels are chronically elevated.
Weight Gain and Obesity
Chronically elevated levels of cortisol leads to weight gain. Consistently high blood glucose levels along with insulin suppression lead to cells that are starved of glucose. This activates hunger signals to the brain causing overeating and cravings for high-calorie foods. Studies have demonstrated a direct association between cortisol levels and calorie intake in populations of women.
Immune System Suppression
Cortisol functions to reduce inflammation in the body, which is good, but over time, these efforts to reduce inflammation also suppress the immune system. Chronically elevated cortisol is associated with an increased susceptibility to colds and other illnesses, an increased risk of cancer, the tendency to develop food allergies, and an increased risk of autoimmune disease.
Cortisol activates the sympathetic nervous system, As a rule, the parasympathetic nervous system must then be suppressed, since the two systems cannot operate simultaneously. The parasympathetic nervous system is stimulated during eating, which is important for digestion and absorption. Digestion and absorption are compromised,
Cortisol constricts blood vessels and increases blood pressure to enhance the delivery of oxygenated blood. This is advantageous for fight-or-flight situations but not perpetually. Over time, such arterial constriction and high blood pressure can lead to vessel damage and plaque buildup, increasing the incidence of Heart disease and stroke.
Elevated cortisol relating to prolonged stress can lend itself to erectile dysfunction or the disruption of normal ovulation and menstrual cycles..
Cortisol secretion has a normal diurnal rhythm. With aging and chronic stress this rhythm is altered. Cortisol should be highest in the morning and low at night. Elevation of cortisol at night down regulates melatonin receptors and causes insomnia.
Cortisol elevation over time causes shrinkage of the hippocampus, an area of the brain where memory is stored. High levels of cortisol cause memory problems.
Assessing Cortisol Levels
The best way to evaluate cortisol is a salivary test, Four saliva samples are taken every 6 hours. A blood cortisol test is available, but it is considered inferior to the salivary test as it tests cortisol levels only at one given point in time and may miss alterations in diurnal rhythm of cortisol. A 24 hour urine for free cortisol is also frequently ordered by physicians but averages the cortisol over time again missing the diurnal rhythm of cortisol.
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