Coffee truly might be the magic bean. Not only have studies shown it to fight various forms of cancer and lower your risk of suicide and dementia, now new research sheds light on why it appears to be good for your cardiovascular health.

Previous research has shown that moderate coffee consumption may have cardiovascular benefits. It may be because it helps your blood vessels work better, according to a new Japanese study, USA Today reports.

Masato Tsutsui, a cardiologist and professor at the University of the Ryukyus in Okinawa, Japan, and her colleagues took 27 healthy adults (ages 22 to 30) who did not regularly drink coffee and had each consume a 5-ounce cup of either regular or decaffeinated. They then measured reactive hyperemia in the participants' left index fingers. This is a measure of how well small blood vessels function. Two days later, the researchers repeated the procedure with the other type of coffee.

The scientists found that the caffeinated coffee drinkers had a 30% increase in vascular function in their index fingers over a 75-minute period, compared with those who drank decaffeinated coffee.

Caffeinated coffee also slightly raised participants' blood pressure and decreased finger blood flow, compared with decaf. Heart rate levels were the same whether participants drank decaf or regular. The findings were presented Wednesday at an American Heart Assn. meeting in Dallas.

“Our findings give us a clue about how coffee may improve cardiovascular health,” Tsutsui said — that is, by improving blood vessel function.

On the other hand, while small amounts of coffee may have a benefit, higher amounts raise blood pressure and heart rate and make you more prone to heart palpitations, according to the AHA.

A study released last year showed that regular, moderate coffee consumption may significantly reduce a person's risk of heart failure, according to USA Today. It found that drinking 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 — five to six cups a day — may increase the chance of serious heart problems.

But keep in mind that this latest study was just 27 Japanese people drinking two cups of coffee. You might have come up with something more sophisticated for your high school science project.

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