What is the HPA axis and what are its main components?
The Hypothalamic-Pituitary-Adrenal (HPA) axis is the central stress response system.
Components:
- Hypothalamus: releases CRH (corticotropin-releasing hormone)
- Pituitary gland: releases ACTH (adrenocorticotropic hormone)
- Adrenal cortex (zona fasciculata): produces cortisol in response to ACTH
What are key factors that can disrupt the HPA axis?
Chronic psychological stress, trauma, infections, inflammation, sleep deprivation, circadian rhythm disruption (shift work, light at night), poor diet, blood sugar instability, overtraining, chronic illness, toxin exposure (mold, chemicals).
How does hypoglycemia affect the HPA axis?
Hypoglycemia activates the HPA axis via the hypothalamus detecting low glucose.
- CRH → ACTH → cortisol release
- Cortisol mobilizes glucose via gluconeogenesis
- Chronic low blood sugar can overactivate HPA axis and dysregulate cortisol rhythm.
How does hyperglycemia and insulin resistance affect the HPA axis?
Chronic hyperglycemia increases systemic inflammation → stimulates HPA axis.
Insulin resistance elevates cortisol due to ongoing stress signals and altered metabolic signaling.
Cortisol also worsens insulin resistance by antagonizing insulin action on cells.
Where is cortisol produced?
Zona fasciculata of the adrenal cortex produces cortisol in response to ACTH from the pituitary.
ACTH release is stimulated by CRH from the hypothalamus during stress.
What are the main biological effects of cortisol on immune function?
Acute: Anti-inflammatory, suppresses immune overreaction.
Chronic: Immune suppression (increased infection risk), impaired mucosal immunity, dysbiosis risk, reduced wound healing.
What are the main biological effects of cortisol on metabolism?
Increases gluconeogenesis, mobilizes amino acids from muscle, mobilizes fatty acids from fat tissue, antagonizes insulin, preserves glucose for the brain, promotes central fat storage if chronically elevated.
What are the main biological effects of cortisol on bone health?
Chronically high cortisol reduces bone formation by inhibiting osteoblast activity, increases bone resorption, decreases calcium absorption, increases calcium excretion → risk of osteoporosis.
What factors can cause high cortisol?
Chronic stress, inflammation, pain, infections, overtraining, blood sugar instability, stimulants (caffeine, nicotine), circadian disruption, unresolved trauma, certain medications (glucocorticoids).
What are common symptoms of high cortisol?
Central weight gain, insomnia, anxiety, muscle wasting, high blood sugar, low immunity, digestive issues, irregular cycles, low libido, bone loss, brain fog.
What protocols can support high cortisol clients?
Reduce stress load (mindfulness, breathwork), balance blood sugar (protein/fat with meals), improve sleep hygiene, reduce stimulants, support circadian rhythm (morning light, limit night light), adaptogens (ashwagandha, reishi, holy basil), magnesium, vitamin C, phosphatidylserine.
How does cortisol normally follow a diurnal rhythm?
Peak: ~30 minutes after waking (Cortisol Awakening Response)
Gradual decline through the day
Lowest: around midnight
Disruption: chronic stress, inflammation, or shift work can flatten curve.
How does cortisol affect inflammation?
Acute: reduces inflammation by suppressing pro-inflammatory cytokines.
Chronic: dysregulates immune system, can cause both immune suppression and increased inflammatory signaling depending on tissue context.
How does exercise affect the HPA axis?
Moderate exercise: healthy stimulation of HPA axis, improves resilience.
Excessive/high-intensity without recovery: chronic cortisol elevation, HPA dysregulation.
What nutrients are important for healthy cortisol regulation?
Vitamin C, magnesium, B vitamins (B5 for adrenal function), zinc, omega-3 fatty acids, adequate protein, electrolytes (Na, K).
How does cortisol increase blood glucose availability? Stimulates gluconeogenesis in the liver, converting amino acids and glycerol into glucose to ensure the brain has enough fuel during stress or fasting.
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How does cortisol mobilize stored fuel for glucose production? Promotes protein breakdown in muscle to release amino acids and stimulates lipolysis in adipose tissue to release glycerol and free fatty acids.
How does cortisol interact with insulin?
Cortisol antagonizes insulin by reducing glucose uptake in muscle and fat, preserving glucose for the brain (‘glucose sparing’). Chronic high cortisol can contribute to insulin resistance.
How does cortisol support glucagon in blood sugar regulation? .
Cortisol works with glucagon to increase blood glucose, especially during fasting, illness, or prolonged stress.
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What is the relationship between cortisol and post-meal blood glucose?
Normally, cortisol is low post-meal, allowing insulin to act. High cortisol blunts insulin effect, causing prolonged elevated blood sugar
What is the effect of high cortisol during stress on glucose?.
Acute stress: boosts glucose to supply brain and muscles. Chronic stress: sustained high glucose and insulin resistance
What happens with low cortisol (adrenal insufficiency) and glucose regulation?
Poor gluconeogenesis, increased risk of hypoglycemia, especially during fasting or overnight.
happens to glucose regulation during fasting with adequate cortisol?
Cortisol promotes gluconeogenesis and limits insulin action so glucose levels remain stable to supply the brain
