3 to 5 Cups of Coffee a Day May Lower Risk of Heart Attacks

Woman drinking coffee
(Image credit: Subbotina Anna | Shutterstock.com)

Good news for people who drink coffee every day: Consuming a moderate amount of coffee could lower the risk of clogged arteries that can lead to a heart attack, a new study finds.

The study of healthy young adults in Korea found that, compared with people who didn't drink coffee, those who drank three to five cups of java per day had a lower risk of having calcium deposits in their coronary arteries, which is an indicator of heart disease. (The coronary arteries are the vessels that bring oxygenated blood to the heart muscle itself.)

The study participants who drank three to four cups had the lowest risk of developing clogged arteries seen in the study, said Dr. Eliseo Guallar, an epidemiologist at Johns Hopkins University Bloomberg School of Public Health in Baltimore, Maryland, and co-author of the study published today (March 2) in the journal Heart.

"But the risk went down with just one cup per day," compared with the risk of people who drank no coffee, Guallar added.

Still, the researchers stopped short of recommending that people drink coffee to prevent heart disease. [Coffee's Perks: Studies Find 5 Health Benefits]

Coffee and heart disease

It was once thought that drinking coffee could make you more prone to heart attacks, but a growing body of evidence suggests the habit has a neutral or beneficial effect on cardiovascular health.

A previous analysis of 36 studies found that moderate coffee consumption was associated with a lower risk of heart disease, and other studies have found a link between drinking coffee and a reduced risk of type 2 diabetes. However, the caffeinated beverage has also been linked to increased LDL cholesterol (the so-called "bad" cholesterol) and increased blood pressure (but this effect diminishes as people build up a tolerance).

In the new research, Guallar and colleagues at the Kangbuk Samsung Hospital in Seoul, South Korea, studied more than 25,000 men and women who underwent routine examinations. The participants had no signs of heart disease, and their average age was 41 at the study's start.

The participants completed questionnaires about their eating and drinking habits (including coffee consumption), and underwent a computed tomography (CT) scan to determine their levels of coronary artery calcium (CAC).

CAC is a sign of coronary artery disease, or atherosclerosis, which increases the risk of cardiovascular disease, especially heart attacks, Guallar said. "You can have the disease for many years without symptoms," he told Live Science, adding, "Now with this technique, we can know if people have the disease way before they have symptoms."

The researchers compared people's CAC levels with their amount of coffee consumption, classified as one cup a day, one to three cups a day, three to five cups a day and at least five cups a day. They also took into account factors such as physical activity, smoking, BMI and how much fruit, vegetables and red meat people ate.

3 to 5 cups a day keep the doc away

The average coffee consumption of those in the study was 1.8 cups per day, and 13.4 percent of all the participants had detectable levels of CAC.

The people who drank three to five cups of coffee daily had about 40 percent less calcium in their arteries than those who drank no coffee, according to the study. Those who drank one to three cups daily had 35 percent less calcium than those who didn't drink coffee, and those who drank one cup a day had 23 percent less calcium.

The people in the study who drank five or more cups a day had 19 percent less calcium, compared with those who drank no coffee.

Guallar stressed that the findings show a correlation between coffee consumption and heart disease risk, but do not prove that a cause-and-effect relationship exists between drinking coffee and having less calcium in the arteries.

While scientists don't have a clear idea how coffee may lower the risk of arterial disease, it may be due to the beverage's many antioxidants, the researchers said.

"This is probably the largest study to date looking at the association of coffee consumption with a marker of subclinical atherosclerosis," said Jared Reis, an epidemiologist at the National Heart, Lung, and Blood Institute in Bethesda, Maryland, who was not involved in the study.

The findings are consistent with those of other recent studies, Reis told Live Science. And although the study involved only Korean participants, he said he didn't "see any reason why the results wouldn’t be generalizable to other populations."

The study didn't distinguish between drinking caffeinated or decaf coffee. But decaf isn't very popular yet in Korea, Guallar said. In any event, caffeine is just one of many substances in coffee, and probably isn't the one that causes the heart disease benefits, he said.

Follow Tanya Lewis on Twitter. Follow us @livescience, Facebook& Google+. Original article on Live Science.

Tanya Lewis
Staff Writer
Tanya was a staff writer for Live Science from 2013 to 2015, covering a wide array of topics, ranging from neuroscience to robotics to strange/cute animals. She received a graduate certificate in science communication from the University of California, Santa Cruz, and a bachelor of science in biomedical engineering from Brown University. She has previously written for Science News, Wired, The Santa Cruz Sentinel, the radio show Big Picture Science and other places. Tanya has lived on a tropical island, witnessed volcanic eruptions and flown in zero gravity (without losing her lunch!). To find out what her latest project is, you can visit her website.