Cortisol is one of forty stress hormones from the adrenal glands called glucocorticoids. The adrenals sit atop the kidneys and are divided into two areas: the adrenal medulla and adrenal cortex. The medulla produces epinephrine and norepinephrine (noradrenaline) used for immediate fight-or-flight response. The cortex has several zones that produce the glucocorticoids (including cortisol) and mineralocorticoids, which regulate electrolytes and fluid balance and impact blood pressure. Along with cortisol, the other key hormones are dehydroepiandrosterone (DHEA) and aldosterone.
Cortisol production is tightly regulated by feedback mechanisms in the midbrain, hypothalamus, and pituitary gland, with rising cortisol shutting down further stimulation of the adrenal glands. This feedback loop is called the hypothalamic-pituitary-adrenal (HPA) axis. However, in a state of continued stress, including the wrong foods and eating habits, the feedback loop between the brain and the adrenal glands’ cortisol production breaks down, leading to inappropriate levels of cortisol.
Elevated Cortisol Causes:
Elevated cortisol, from poor dietary habits or other chronic stress, leads to a change in the brain and endocrine system called allostasis. This revolutionary new concept describes the stress response as not simply a short-term adjustment that eventually returns the body to a preset level of cortisol secretion, but a more permanent change in the control over stress-hormone production. Even if the original stressful event has been resolved, a new set point might continue, leading to ongoing excess cortisol production.
The damage that occurs from this new set point of cortisol production is called allostatic load, made even worse by poor dietary habits and nutritional deficiencies. Eventually, the wear and tear of poor adaptation and allostatic load, coupled with the brain’s fail-safe shutdown of chronic cortisol elevation, lead to a failure of normal cortisol regulation, inhibiting additional cortisol secretion by the adrenal glands. This leads to fatigue, anxiety, depression, poor resistance, and an inability to recover effectively from life’s challenges.
Emotional states impact adaptation and cortisol levels as well. The brain, through the limbic lobe (the emotional center), connects emotions and perceptions of the world with the appropriate level of cortisol production and nervous system stimulation.
Fear, worry, anxiety, or the anticipation of a stressful experience is enough to trigger the brain to initiate the biochemistry of stress. Poor diet, lack of exercise, and obesity also increase cortisol levels and allostatic load. Many people are more prone to be emotionally stressed because of poor dietary habits, which change the brain’s chemistry and reduce their ability to adapt, leading again to more cortisol. Even more problematic is the fact that elevated cortisol itself alters the emotional stress response, increasing allostatic load, obesity, and disease.
Stages of Stress Response
• The brain experiences or thinks of something stressful.
• An immediate release of norepinephrine and epinephrine from the adrenal medulla and sympathetic nervous system occurs.
• This raises heart rate, blood pressure, and respiration rate and shunts blood from the digestive tract to the muscles.
• If stress is not resolved immediately, the brain secretes CRH (corticotropin-releasing hormone).
• CRH causes the release of ACTH (adrenocorticotropic hormone) within fifteen seconds and the subsequent release of cortisol from the adrenal glands.
• The pancreas releases glucagon, which raises the circulating levels of glucose for use by the brain and muscles for energy during the stress.
• The pituitary gland releases prolactin to suppress reproductive activity and reduce testosterone, estrogen, and progesterone.
• Thyroid function and growth-hormone production are inhibited.
• Endorphins, enkephalins, and vasopressin are secreted to suppress pain and improve cardiac function.
• If the stress continues, many of these effects become chronic and cause continued alterations in physiology.
• Chronic stress leads to elevated blood glucose, insulin resistance, depressed sexual function, weight gain, suppressed immunity, and elevated blood pressure and heart rate.