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U.S. Secretary of State Hillary Clinton drinking coffee at the United Nations Human Rights Council in Geneva this week. Photo by Reuters
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Consuming the equivalent amount of caffeine found in three cups of coffee is good for the circulatory system and protects against heart attacks, researchers at the Sheba Medical Center have found. The results of their study were published this week in the American Journal of Cardiology.

This would seem to negate the conventional wisdom, as cardiologists tend to advise their patients to reduce coffee consumption, on the grounds that caffeine increases the pulse rate and blood pressure, requiring more oxygen for the heart to function properly.

The research team, headed by Prof. Michael Shechter, the director of the clinical research unit at the Heart Institute at Sheba, examined the effect of caffeine consumption on the cardiovascular system. Eighty adults participated in the study, half of them healthy and half of them heart patients. The participants were asked to come to the institute two times, a week apart, and take a 200 mg. pill of caffeine, equivalent to the amount of caffeine found in three cups of coffee. Each participant received the caffeine pill on one visit and a placebo on the other, in a double-blind test where neither researcher nor subject knew which pill was taken when.

An hour after the pill was taken, blood samples were taken and ultrasounds were conducted of the hand artery to examine how the endothelium, the innermost layer of the artery, was functioning. "In the past, it was believed that this is only an isolated layer of the artery, but over the past decade, it was discovered that it secretes substances that maintain proper blood flow, enables the expansion of blood vessels and prevents an inflammatory process as well as the accumulation of fats along the blood vessel walls," explained Shechter. "When this layer is damaged, atherosclerosis [hardening of the artery walls] develops."

The study found that caffeine consumption improves the functioning of the endothelium by 30 percent, reduces by 40 percent the C-reactive (CRP ) protein in the body , a leading predictor of heart attacks and stroke, and increases by 25 percent the amount of adiponectin, a protein which prevents heart attacks and strokes.

The benefits of caffeine were detected in both the heart patients and the healthy patients. "Coffee sometimes also contains milk, sugar or artificial sweetener, and artificial flavors and coloring," Shechter noted, "but the study only looked at the impact of caffeine. We found this substance did have a benefit related to improving the vascular functioning of the body." He said it is still not clear what the effect of coffee consumption is over the long-term, but that over the course of several hours, its effect is positive. "I wouldn't prohibit heart patients from drinking a reasonable amount of coffee, say three cups a day," he said. The researchers plan to expand their study to the long-term effects of caffeine consumption on the cardiovascular system.

The findings of the Sheba team are surprising given recent warnings issued against increased caffeine consumption. In October 2010, the Health Ministry recommending banning the sale of energy drinks to adolescents over concerns regarding increased caffeine consumption. According to medical studies, excess caffeine consumption can cause side effects like anxiety, tension, headaches, agitation and insomnia.

But the findings of the Israeli researchers correspond with similar findings around the world in recent years. In a study published in January in the journal Heart, American researchers reported that based on research conducted among 59,490 people in Finland, aged 25 to 74, drinking coffee did not increase the risk of heart failure. Researchers from Germany reported in April 2010 that the daily consumption of four to eight cups of coffee increased good cholesterol (HDL ) levels. British researchers reported in January 2010, based on an analysis of brain tumors among cancer patients in Europe, that consumption of coffee and tea reduces the risk of developing a type of cancerous tumor known as glioma.