In a small clinical study, scientists in Japan found that three cups of green tea a day appear to lower the blood concentration of nadolol, a beta-blocker.
Green tea and a common medication for high blood pressure may not mix well, new research suggests.
The antioxidant-rich beverage appears to reduce the effects of beta-blocker nadolol, scientists in Japan reported.
“We’d like to raise the possibility that green-tea consumption may change the plasma concentrations and pharmacological effect of nadolol,” Dr. Shingen Misaka of Fukushima Medical University told Medscape.com.
But, he added, the research “was just a small study in healthy adults.”
“Therefore, we consider that it’s still insufficient to expand our findings to other beta-blockers, all green-tea products and of course hypertension patients,” he said, according to Medscape. “Further studies in a large population and different age groups will be needed.”
The study, to be published in the journal Clinical Pharmacology & Therapeutics, looked at 10 men and women ages 20-30 who were of normal weight, were nonsmokers and had no existing medical conditions.
The subjects drank three cups of either green tea or water every day for two weeks while taking a 30-milligram dose of nadolol. After two weeks off, they switched to the other beverage and again took the medication for two weeks.
Green tea appeared to lower the concentration of nadolol in the blood by 76% compared to the water. Scientists say they believe, based on other experiments, that antioxidant EGCG is the cause.
EGCG is the property in green tea thought to provide protection against inflammation and cancer-causing free radicals. The new warning is all the more important because green tea is increasing in popularity as a healthy drink, researchers noted.
Nadolol is marketed in the U.S. under the brand name Corgard, and is also a component of the drug Corzide.
If you are taking nadolol, it’s important not to stop taking it without first consulting your doctor. Doing so could cause chest pain or heart attack, according to the National Institutes of Health’s MedlinePlus.
Source: tmiller@nydailynews.com