Does Caffeine Constrict Blood Vessels?

Caffeine can affect the body and brain in a number of ways. While it is most commonly used for alertness and mental focus, caffeine consumption does have other possible side effects that should not be overlooked. Blood vessel constriction, also known as vasoconstriction, is one of these potential side effects.

Two business people sitting together drinking mugs of coffee. Credit: Digital Vision./Photodisc/Getty Images

Caffeine's Effects on the Body

Caffeine, a substance found naturally in tea leaves, kola nuts, cocoa beans and coffee, quickly passes into the brain once ingested. It then stays in the body for many hours, which means its effects can last for hours. Among the potential side effects of caffeine include increased heart rate, anxiety, difficulty sleeping, nausea, restlessness and frequent urination. Suddenly stopping caffeine use can cause withdrawal symptoms, including drowsiness, headaches and irritability.

Causes of Vasoconstriction

Vasoconstriction is the narrowing of blood vessels. When vasoconstriction occurs, blood flow is slowed down or partially blocked. It can occur in response to psychological conditions or drugs, such as decongestants, pseudoephedrine or caffeine. According to MedlinePlus, medications exist to both increase and reduce vasoconstriction, depending in the condition being treated.

Caffeine, Vasoconstriction and the Brain

A study published in 2009 in "Human Brain Mapping" set out to determine the effect of caffeine on cerebral blood flow. The researchers found that caffeine use reduced cerebral blood flow by an average of 27 percent. This means that, while caffeine is known for improving mental energy, it can actually reduce the total amount of blood in the brain, which could potentially result in reduced cognitive function.

Limiting Caffeine Intake

By limiting your caffeine intake, you may be able to avoid vasoconstriction and decreased blood flow in the brain. The study published in "Human Brain Mapping" found that those who consumed high levels of caffeine had less cerebral blood flow, when compared to low and moderate caffeine users. In the study, 45 milligrams per day was considered low dosage, 405 milligrams per day was considered moderate and 950 milligrams per day was considered a high level of caffeine.

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