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Green Tea May Weaken Effectiveness of Blood Pressure Medication, Study Finds

Green tea is high in antioxidants and potentially has many health benefits – but a recent study shows that it may also interact with medications.
Japanese researchers from Fukushima Medical University have discovered that the tea can inhibit the effects a common drug prescribed to control blood pressure. Nadolol, which goes by the brand name Corgard, is inhibited from absorption into the bloodstream probably due to one of the prized antioxidants in the tea leaves.

The research found that people in a test study who drank green tea while on a course of the blood pressure tablets had lower circulating blood levels of nadolol. Green tea dilutes the blood-pressure medication by reducing its concentration in the bloodstream by up to 75 percent. It is not clear if other types of teas have a similar effect. The study was performed on only ten volunteers.

Sotiris Antoniou, a Royal Pharmaceutical Society spokesman and a consultant pharmacist in cardiovascular medicine, told BBC News he recommends that blood pressure patients who still want green tea leave a four-hour gap between drinking the beverage and taking their medicine.

It is unknown if the malabsorption affects the drug’s ability to treat hypertension effectively. Ironically, green tea is also touted to lower blood pressure.

For the last twenty years, the results of thousands of studies have been in favor of the green leaf drink for its high antioxidant content that repairs damage and aging at the cellular level. It is also used  to improve blood flow leading to a healthier heart and brain, as well as increase weight loss and curb diabetes and other diseases.

So should this study concern individuals who are on other medications and drink green tea on regular basis?

According to Antoniou, “For any individual concerned, they can go to their local community pharmacy where they can clarify any potential interaction.”

S.C. Rhyne is a blogger and novelist in New York City. Follow the author on twitter @ReporterandGirl or on and visit her website at

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