A new study suggests that patients who are taking blood pressure medication should avoid drinking green tea.
Researchers from the Shingen Misaka at the Fukushima Medical University in Japan and from other universities in Italy and Germany concluded that patients taking nadolol, a medication used to cure high blood pressure, should avoid taking green tea since it lessens the efficacy of the drug.
They recruited 10 volunteers who were asked to take a dose of 30 mg of nadolol along with water or around three cups of green tea for 14 days. After which, they measured the blood levels of the participants and found out that the group who drank green tea has blood levels 76 percent lower than those who drank water.
According to the researchers, there are some ingredients in the green tea which interferes with the absorption of nadolol in the intestine. Nadolol is considered a beta blocker, a family of drugs used to cure angina and high blood pressure. According to the American Heart Association, beta blockers work by reducing the heart's workload, the heart rate, and the overall output of the blood, with the goal to lower the blood pressure.
"Individuals who take nadolol and also consume green tea should be aware of this potential interaction and discuss this with their physician," said Dr. Gregg Fonarow, a cardiology professor at the University of California, L.A and American Heart Association spokesman, to Medical Xpress. Dr. Fonarow reviewed the results but he was not involved in the study.
Researchers noted that although the study showed decreased levels of nadolol for patients who consumed tea, data is not enough to establish a cause and effect relationship. They stated that larger studies should be done to further understand how nadolol and green tea reacts with each other.
Findings of the research were published online on Jan. 13 in Clinical Pharmacology & Therapeutics.