Drinking Green Tea May Interfere With The Medication You Take

With so much new information coming out daily relating to health, it can be difficult to know what habits still remain healthy and what researchers say no longer makes the grade. Multivitamins and nutritional supplements, for example, where long considered an important part of maintaining a healthy and balance diet. But in the last few months, a number of studies were released that questioned whether multivitamins and supplements have any noticeable effect on the body at all.


A recent John Hopkins University School of Medicine report even went so far as to call multivitamins a waste of money, and consumers would be better off spending their money on buying fresh fruits and vegetables they could add to their diets instead.

Now the latest food item to suffer a hit to its healthy reputation is green tea, according to a new study. Researchers at Fukushima Medical University in Japan have found that drinking green tea may lessen the effectiveness of nadolol, a medication used to treat patients with high blood pressure.

Researchers provided study participants a single dose of nadolol after they had drank either water or roughly three cups of green tea a day for two weeks.

When researchers tested for levels of the drug in the participants’ blood, they discovered levels 76 percent lower in individuals who had regularly consumed green tea when compared to those who drank water.

Based on the results of this study, researchers now caution patients suffering from high blood pressure to avoid drinking green tea, and are now left to wonder what other types of medications the beverage may also interfere with.

The results of the study were published online in the journal Clinical Pharmacology & Therapeutics.

A Cause for Concern?

Green tea has established the reputation as being one of the healthiest beverages people can enjoy. While this reputation seems to come more from the tea’s history –it has been part of Indian and Chinese medicine for hundreds of years – than hard science, studies have suggested that drinking green tea can help an individual lower their risk for a number of chronic health problems, including heart disease, diabetes, gingivitis and even certain forms of cancer.

While these claims have yet to be proven, the results of this latest study could be a cause for concern for patients taking prescription medications, while also trying to reap the potentially healthy benefits of green tea.

Researchers also caution that nadolol isn’t the only drug on the market that can be negatively influenced by what a patient eats or drinks. Grapefruit and grapefruit juice, for example, have also been shown to interfere with taking certain medications, especially those used to treat high blood pressure and cholesterol.

Nadolol works as a beta block, meaning that it reduces a patient’s heart rate and heart workload in order to reduce blood output, thereby lowering blood pressure. Most beta blockers enter a patient’s bloodstream through intestinal absorption. Certain compounds found in green are believed to interfere with absorption of medication through the intestine, according to researchers.

A drastic reduction in the amount of a blood pressure medication a patient receives – such as the 75 percent researchers found was lost in patients who regularly drank green tea – can have a dramatic impact on a patient’s treatment for the disease.

Give Up the Green?

As with most things, moderation seems to play an important role in whether patients on medications can continue to enjoy green tea and other foods and beverages that interfere with treatment.

In this particular study, participants consumed an average of three cups of green tea a day, an amount that isn’t typical in most Western diets. Researchers recommend that for those who drink more than several cups of green tea a day while on medication to reduce that number to one or two cups daily. Patients are also advised to talk with their doctor regarding the medication they take and whether drinking tea may interfere with treatment.

John Nickelbottom is a freelance health and scicence writer.

Leave a Reply