Quick answer: Caffeine in coffee stimulates the release of cortisol, the body’s primary stress hormone.
Coffee is one of the world’s most widely consumed beverages. Drinking coffee can have a range of effects on the human body due to its complex chemical composition. One of the key active compounds in coffee is caffeine, which is known to stimulate the central nervous system and have effects on various hormones in the body.
How does coffee increase cortisol levels?
Cortisol is often referred to as the “stress hormone” as it is released in response to both physical and psychological stressors. Cortisol plays an important role in the body’s stress response system by helping regulate blood pressure, blood sugar levels, metabolism, and immune function.
When you drink coffee, the caffeine is rapidly absorbed into the bloodstream and travels to the brain. In the brain, caffeine blocks the inhibitory effects of adenosine, resulting in increased firing of neurons and release of excitatory neurotransmitters like dopamine and norepinephrine.
This brain stimulation signals the adrenal glands to secrete cortisol and adrenaline. Cortisol levels typically peak between 30-60 minutes after caffeine consumption. The magnitude of the cortisol response depends on factors like the amount of caffeine ingested, size of the coffee drinker, and individual sensitivity to caffeine.
Other effects of cortisol
In addition to increased energy and alertness, elevated cortisol from coffee can have other effects:
Metabolism
Cortisol increases glucose levels in the bloodstream to provide immediate energy. It also mobilizes amino acids from muscle tissue into the bloodstream.
These metabolic effects provide the body with fuel to respond to the perceived stress of caffeine ingestion. Over time, repeated cortisol elevations from coffee may contribute to insulin resistance.
Anti-inflammatory
Cortisol helps suppress the immune system and inflammation in the short term. This anti-inflammatory effect may explain why regular coffee drinkers have a lower risk of certain inflammatory disorders.
However, chronic coffee intake and repetitive cortisol spikes may lead to impaired immune function.
Heart health
Acute cortisol elevation from coffee causes an increase in blood pressure and heart rate. Cortisol also elevates homocysteine, a compound linked to cardiovascular disease risk.
For individuals with high blood pressure or heart conditions, repeated cortisol spikes from coffee may increase the risk of heart attack or stroke. Those with normal blood pressure are less likely to experience adverse cardiovascular effects.
Other hormones affected by coffee
While cortisol is the main hormone increased, drinking coffee may also influence other hormone systems:
Adrenaline
Along with cortisol, the adrenal glands secrete adrenaline (epinephrine) in response to coffee. Adrenaline is responsible for the “fight-or-flight” response. It increases heart rate, blood pressure, breathing rate, and energy production.
Estrogen
Coffee may reduce the reabsorption of estrogen in the liver, leading to marginally higher blood levels of estrogen. More research is needed to confirm this effect.
Human growth hormone
A study in 18 young adults found that consuming caffeinated coffee led to a significant increase in growth hormone levels for up to 3 hours. Growth hormone has anabolic effects in the body and helps regulate metabolism.
Prolactin
High levels of caffeine from coffee can inhibit the release of prolactin, a hormone involved in breast milk production. This may explain why pregnant women are advised to limit caffeine intake.
How much coffee is safe?
Up to 400 mg of caffeine per day (equivalent to about 4 cups of coffee) is generally not associated with adverse effects in healthy adults. However, effects vary dramatically between individuals.
Those sensitive to caffeine or with anxiety disorders may experience significant cortisol spikes from smaller amounts of coffee. Pregnant women should limit caffeine intake to less than 200 mg per day.
To minimize cortisol spikes, avoid drinking coffee in the late afternoon or evening. Spread out coffee consumption throughout the morning and early afternoon. Also, try to limit sugar and refined carbs along with your coffee to prevent blood sugar crashes later.
The bottom line
Coffee is a double-edged sword. The caffeine provides energy, alertness, and potential health benefits. But it also triggers the body’s stress response, spiking cortisol and adrenaline levels.
Moderate your coffee habit by limiting intake to 1-2 cups in the morning. Avoid late day coffee and added sweeteners to reduce cortisol spikes and crashes. If you experience anxiety, jitteriness, or poor sleep after coffee, consider cutting back or switching to decaf.
