Caffeine & Arteries

Caffeine is ubiquitous in American society and in the global culture, being the most widely used drug worldwide. Its effects vary from a pleasant increase in alertness to less pleasurable nervousness, insomnia or headache. Caffeine is relatively quick acting, with noticeable effects occurring within 15 to 45 minutes after consumption. Part of the reason behind the positive and negative reaction to caffeine is its impact on the cardiovascular system, particularly the arteries.

Effects

Caffeine's effects on arteries involve a chemical in the body called adenosine. This substance helps to induce sleep by slowing activity of the nervous system. It also dilates blood vessels. Caffeine interferes with this chain of events by binding to the receptors on cells for adenosine. This has the opposite effect of adenosine by causing blood vessels to constrict.

Blood Pressure

Blood pressure measures the pressure of blood flow in the arteries. Systolic pressure is the top number and reflects the force of contractions of the heart. Diastolic pressure, the bottom number, shows the pressure within the arteries when the heart is at rest. Since caffeine constricts blood vessels, it will cause a temporary rise in blood pressure due to the narrowing of the space in which blood can flow. A 2010 study by the University of Palermo in Italy documented increases in both systolic and diastolic blood pressure in participants consuming caffeinated coffee.

Heart Rate Rhythm

Regardless of any effects on the arteries, the heart still must supply adequate amounts of blood throughout the body. To accomplish this, the heart rate rhythm will change to reflect the effects of caffeine on blood vessel constriction. A 2010 study by University of Medicine and Science - Chicago Medical School points out that caffeine may induce arrhythmia or irregular heartbeat. While harmless in most cases, the potential exists for worsening of symptoms in individuals with damaged heart tissue.

Fight-or-flight Response

In some ways, the arteries' reaction to caffeine mimics the effects of the fight-or-flight response initiated by the nervous system. When you exercise or are in a stressful situation, your heart rate and blood pressure increase to help deliver blood and oxygen more quickly to your muscles. Caffeine acts similarly by constricting blood vessels and can offer some benefits in terms of athletic performance. A 2011 study by Carnegie Research Institute and Leeds Metropolitan University in the United Kingdom concluded that caffeine enhanced endurance by positively affecting perceived exertion levels, allowing participants to exercise more effectively. If you have concerns about caffeine and cardiovascular health, consult your doctor.