According to new research, the first cup of coffee of the day may damage arteries, the European Society of Cardiology was told in Stockholm on September 3, the Daily Telegraph London reports. Dr Charalambos Vlachopoulos, of Henry Dunant Hospital, Athens, Greece, who has studied the effects of coffee on blood vessels, said: "Our study demonstrates that just one cup of coffee could stiffen one's arteries." According to his study, this could lead to systolic hypertension, a blood pressure condition common among elderly people. The effect of one cup of coffee lasted for 2-3 hours, he said, and the first breakfast coffee after fasting all night may be the worst. The stiffening effect was measured by recording a blood pressure wave in the forearm. When the blood is pumped around the body, the surge is called a reflected wave. Given the physics property that a wave travels faster in a rigid tube, the researchers were able to make their measurements. Subjects in the trial were given a 100mg caffeine capsule, the equivalent of one cup of coffee or a placebo capsule. Half way through the study the capsules were swapped around. According to Dr Vlachopoulos, one of the consequences was that the heart found it more difficult to pump against stiff rather than flexible arteries and that stiff arteries were more prone to rupture and losing their protective linings. However, according to Dr Vlachopoulos, more research is necessary to determine how much coffee, if any, could be consumed without risk.