Coffee may help perk up your blood vessels

The caffeine in a cup of coffee might help your small blood vessels work better, according to research presented at the American Heart Association's Scientific Sessions 2013.

A study of 27 healthy adults showed – for the first time – that drinking a cup of caffeinated coffee significantly improved blood flow in a finger, which is a measure of how well the inner lining of the body's smaller blood vessels work. Specifically, participants who drank a cup of caffeinated coffee had a 30 percent increase in blood flow over a 75-minute period compared to those who drank decaffeinated coffee.

"This gives us a clue about how coffee may help improve cardiovascular health," said Masato Tsutsui, M.D., Ph.D., lead researcher and a cardiologist and professor in the pharmacology department at the University of the Ryukyus in Okinawa, Japan.

The study adds to a growing body of research about coffee, the most widely consumed beverage worldwide. Previous studies showed that drinking coffee is linked to lower risks of dying from heart disease and stroke, and that high doses of caffeine may improve the function of larger arteries.

Study participants were people who did not regularly drink coffee, ranging in age from 22 to 30. On one day, each participant drank one five-ounce cup of either regular or decaffeinated coffee. Then researchers measured finger blood flow with laser Doppler flowmetry, a non-invasive technique for gauging blood circulation on a microscopic level. Two days later, the experiment was repeated with the other type of coffee. Neither the researchers nor the participants knew when they were drinking caffeinated coffee.

The researchers noted blood pressure, heart rate, and vascular resistance levels. They also took blood samples to analyze levels of caffeine and to rule out the role of hormones on blood vessel function.

"This is an intriguing observation that may help us understand why consumption of coffee may be beneficial," said Tomaselli, former president of the American Heart Association.

The study involved 27 healthy adults, aged 22 to 30, who did not regularly drink coffee. They were asked to drink a 5-ounce cup of either caffeinated or decaffeinated coffee. Researchers then measured their finger blood flow using a noninvasive laser technique for gauging blood circulation.

Two days later, the experiment was repeated with the other type of coffee. Neither the researchers nor the participants knew when they were drinking caffeinated coffee.

The researchers found that blood flow in the small blood vessels improved by nearly one-third among the people who drank caffeinated coffee. The effect continued in those people over a 75-minute period.

Heart rate levels remained the same between the two groups, although caffeinated coffee slightly raised blood pressure.

The improved blood flow is likely because of improved function of the inner lining of the blood vessels, Tsutsui said. Researchers have linked the function of the lining of blood vessels - also known as endothelial function - to future heart attacks, heart disease and strokes.