Caffeine is a chemical found in several different foods products. You may ingest it in coffee, energy drinks, chocolate, over-the-counter drugs, frozen desserts, soft drinks or tea. Caffeine has several different effects on the body, including raising your heart rate and blood pressure, increasing stomach acid, irritating the stomach lining and increasing the amount of water your body excretes. It also stimulates the cortex of your brain and increases your mental awareness and may be beneficial in the prevention of heart disease, according to Pegasus NLP.
Blood Pressure
Blood pressure is a measurement of the amount force required against the walls of the arteries for the heart to pump blood through the body. The amount of force is impacted by the size of the blood vessels, flexibility of the blood vessels and the amount of blood volume in the body, according to MedlinePlus. It is also affected by your activity, the foods or drugs you take, circulating hormone levels, emotional state, posture, temperature and diet. Your blood pressure is also an indicator of the health of your cardiovascular system and a predictive factor in your risk of cardiovascular disease, stroke and heart attack.
Sympathetic Nerve Activity
The sympathetic nervous system is part of the flight or fight response in the body. When it is activated it diverts blood away from the gastrointestinal tract, and to the muscles and lungs. Your pupils relax for greater distance vision and the vessels around the heart dilate to increase the function of the muscle. Researchers Switzerland recently discovered that the sympathetic nervous system activity is markedly activated with the ingestion of coffee, whether caffeinated or decaffeinated. The research, published in the "Journal of the American Heart Association" in 2002, found that people who were regular coffee drinkers had a great response of the sympathetic nervous system, without an increase in blood pressure. As early as 1977 researchers published findings in the "New England Journal of Medicine" that proved a link between increased sympathetic nervous system activity and the release of plasma renin after administration of caffeine.
Plasma Renin
Renin is an enzyme that is released by the adrenal glands, located on the kidneys, that work in the system to control the body salt and water balance. Doctors will test the amount of renin in the blood stream to determine the type of high blood pressure you are suffering and the best medication to be used, according to MedlinePlus. The administration of caffeine will increase the activity of the sympathetic nervous system and production of renin, which in turn affects the hormonal balance of salt and water in the body. These changes affect your blood pressure measurements.
Catecholamines
Catecholamines is the group name for epinephrine and norepinephrine. They are activated in times of stress. Norepinephrine is also released during increased levels of sympathetic nervous system activity. When there are high levels of sympathetic activity the amount of norepinephrine in the blood stream increases dramatically, according to CV Physiology. This increase results in constriction of the peripheral vascular system, which raises the force against which the heart pumps blood and blood pressure. Although the release of norepinephrine after caffeine ingestion may initially stimulate the heart rate it will decrease as other systems in the body regulate the rate.
References
- Pegasus NLP: Be Careful with Caffeine
- MedlinePlus: Blood Pressure
- Journal of the American Heart Association; "New Buzz on Coffee: It's Not the Caffeine that Raises Blood Pressure"; Roberto Corti MD; November 2002
- New England Journal of Medicine; "Possible Role of Renin in Hypertension as Suggested by Renin-Sodium Profiling and Inhibition of Converting Enzyme"; D Case, J. Wallace, H. Keim et. al.; March 1977
- MedlinePlus: Renin
- CV Physiology: Circulating Catecholamines
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