What to know about new research on coffee and heart risks

Coffee lovers — and their doctors — have long wondered whether a jolt of java can affect the heart. New research published Wednesday finds that drinking caffeinated coffee did not significantly affect one kind of heart hiccup that can feel like a skipped beat.

But it did signal a slight increase in another type of irregular heartbeat in people who drank more than one cup per day. And it found that people tend to walk more and sleep less on the days they drank coffee.

Coffee is one of the most common beverages in the world. In the U.S., two-thirds of Americans drink coffee every day, more than bottled water, tea or tap water, according to the National Coffee Association, a trade group. Coffee contains caffeine, a stimulant, which is widely regarded as safe for healthy adults at about 400 milligrams per day, or roughly the equivalent of four or five