Coffee, a stimulant considered responsible to slow the blood flow to the heart by 22 percent. According to the observational research done on 20 people, it was seen that a shot of caffeine drink such as espresso can raise blood pressure and cause constriction in arteries resulting in low supply of blood.

At the University of Palermo it was observed that after an hour of consumption of the drink the average blood flow was reduced simultaneously resulting in increase rate of blood pressure. It was also stated that the probable cause for the same could be slow caffeine metabolism linked to genes.

However the hunch in this research is the sample size. With small number of twenty individuals, it is difficult to draw any conclusions. Also, the moderate level of difference in blood flow and blood pressure could not be significant enough to reach any conclusion. Although it may prove fatal for the caffeine sensitive lot, otherwise it is a safe drink which can be consumed without health risks (as there is a need for extensive studying this area).