Two or more cups of coffee per day may double the risk of death from cardiovascular disease in people with severe high blood pressure (160/100 mm Hg or higher), but not in those with high blood pressure, according to new research.

1. Drinking two or more cups of coffee a day was associated with twice the risk of cardiovascular disease death in people whose blood pressure was 160/100 mm Hg or higher compared to those who did not drink any coffee.

2. Drinking one cup of coffee a day was not associated with an increased risk of death from cardiovascular disease across any blood pressure categories.

3. Green tea consumption was not associated with an increased risk of cardiovascular disease mortality across any blood pressure categories.

“These findings may support the assertion that people with severe high blood pressure should avoid drinking excessive coffee,” explained the study’s senior author Hiroyasu Iso, M.D., PhD, M.P.H., director of the Institute for Global Health Policy Research and professor emeritus at Osaka University..

“Because people with severe hypertension are more susceptible to the effects of caffeine, caffeine’s harmful effects may outweigh its protective effects and may increase the risk of death.”