Coffee may do more than wake you up. It may help your small blood vessels work better, a new study suggests.
But that doesn't mean you should guzzle gallons of java.
Previous research has shown that moderate coffee consumption may have some beneficial effects on cardiovascular health. However, the precise mechanism for this benefit is unknown, says Masato Tsutsui, one of the authors of the new research and a cardiologist and professor in the pharmacology department at the University of the Ryukyus in Okinawa, Japan.
Tsutsui and colleagues in Japan worked with 27 healthy adults, ages 22 to 30, who did not regularly drink coffee. On one day, each participant drank one 5-ounce cup of either regular caffeinated or decaffeinated coffee. Then researchers measured reactive hyperemia in the participants' left index fingers. This is a measure of vascular function that takes into consideration how well small blood vessels function. Two days later, the researchers repeated the procedure with the other type of coffee.
• Those who drank a cup of caffeinated coffee had a 30% increase in vascular function in the index finger over a 75-minute period, compared with those who drank decaffeinated coffee.
• Caffeinated coffee slightly raised participants' blood pressure and decreased finger blood flow, compared with decaf.
• Heart rate levels were the same when participants drank decaf or regular coffee.
Tsutsui says that caffeine may improve blood vessels' function. "Our findings give us a clue about how coffee may improve cardiovascular health." The new study was funded in part by the All Japan Coffee Association.
However, cardiologist Vincent Bufalino, a spokesman for the heart association and senior vice president for the Advocate Cardiovascular Institute in Chicago, says "it's hard to come to broad-based scientific conclusions based on this one small study. The research is limited to one cup of coffee."
This subject needs further investigation, including looking at what happens when people drink more caffeine, he says.
"Small amounts of coffee may have a benefit, but a higher consumption of coffee definitely raises blood pressure. It definitely raises heart rate, and it makes you more prone to heart palpitations," Bufalino says. "We see that every day in terms of the use of caffeine in patients. A lot of people sense that a cup of coffee gives them a lift but too much can have negative effects."
A study released last year showed that regular, moderate coffee consumption may significantly reduce a person's risk of heart failure. It found that drinking the equivalent of two cups of coffee a day appears to have the most significant benefit on heart health, when compared with no coffee consumption, but that drinking excessive amounts of coffee — five to six commercial coffee house cups a day — may increase the chance of serious heart problems.