Drinking coffee is healthy for some people — but may increase the risk of early death for those with hypertension, study finds

• People with very high blood pressure who drank a lot of coffee were more likely to die from heart problems according to a new study.
• But coffee drinking did not have an impact on people with normal or slightly high blood pressure.

Coffee, generally considered a heart-healthy beverage when consumed in moderation, might be harmful for people with very high blood pressure.

Two or more cups of coffee a day was associated with a higher risk of death from heart problems in people with very high blood pressure, according to a study published on Wednesday in the Journal of the American Heart Association.

Compared to non-drinkers, people who drank two or more cups of coffee were roughly twice as likely to die from heart problems in the study.

Though heavy coffee drinking was more risky for people with severe hypertension, or high blood pressure, the same trend did not occur in people with normal or slightly high blood pressure. The study's authors were a group of Japanese researchers who analyzed the health data of 18,609 participants aged 40 to 79.

Green tea consumption in any amount did not have an impact on heart health, according to the study.

The study was the first to find a link between coffee drinking and death from heart disease in people with very high blood pressure, the study's main author Hiroyasu Iso told the American Heart Association.

Blood pressure is measured by the pressure in your arteries both when your heart beats (systolic blood pressure) and when your heart is at rest (diastolic blood pressure). High blood pressure occurs when your systolic blood pressure is at least 130 millimeters of mercury (mm Hg) over a diastolic blood pressure of at least 80 mm Hg.

Study authors defined "very high" blood pressure as at least 160 mm Hg over at least 100 mm Hg.

"These findings may support the assertion that people with severe high blood pressure should avoid drinking excessive coffee," Iso said in an AHA release.

The AHA does not have an official recommendation on how much coffee to drink, the group has said one to two cups per day "doesn't seem to be harmful" on its website.

Previous research has shown moderate caffeine consumption — around one to three mugs a day — might benefit heart health.

A paper from last year that looked at three studies, including one that followed 21,000 adults over at least 10 years, found drinking two cups of coffee per day could lower the risk of heart failure by 30%. Prior research also found having around three cups of joe a day could lower the risk of heart disease, Insider's Sara Lindberg reported.

Coffee drinking has even been seen to stave off early death, as a large paper from earlier this year that analyzed the health of 171,000 UK residents found regular drinkers of unsweetened coffee were 16 to 21% less likely to die than their java-less peers.

But newer studies have shed light on the potentially negative effects of coffee. A recent paper in the Journal of the American Medical Association found drinking coffee while pregnant could impact the child's height when they grow up.