Green Tea, Coffee Tied To Lower Mortality For Stroke, Myocardial Infarction Survivors

Green tea and coffee drinkers who survive a stroke or myocardial infarction have lower all-cause mortality risk than people who don't consume these beverages, a recent study suggests.

Researchers examined data on 46,213 participants (ages 40 to 79 years) from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC study) who completed questionnaires about demographics, lifestyle, medical history, and diet. After a median follow-up period of 18.5 years, a total of 9,253 patients had died.

Compared to people who didn't drink green tea, heavy tea drinkers who enjoyed at least seven cups a day had significantly lower all-cause mortality when they had a history of stroke (adjusted hazard ratio 0.38) or a history of myocardial infarction (aHR 0.47). Light tea drinkers who had up to six cups a week also had a significantly lower risk of all-cause mortality after surviving a stroke or MI (aHR 0.73 and 0.74, respectively).

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Compared to people who didn't drink coffee, heavy coffee drinkers who enjoyed at least seven cups a day had significantly lower all-cause mortality with a history of MI (aHR 0.61) or without any history of MI or stroke (aHR 0.82). Light coffee drinkers who had up to six cups a week also had a significantly lower risk of all-cause mortality after surviving MI (aHR 0.69) as well as when they had no history of MI or stroke (aHR 0.86).

There was no benefit from green tea evident for people without a history of stroke or MI, and no benefit from coffee drinking for stroke survivors, according to the results published in Stroke.

"Our study suggests that dietary habits such as green tea or coffee consumption can contribute to improved prognosis of CVD survivors," said senior study author Dr. Hiroyasu Iso of Osaka University Graduate School of Medicine in Japan.

"We believe that it is important to accumulate evidence for the secondary prevention of cardiovascular diseases by intervening lifestyle habits such as diet in addition to drug therapy," Dr. Iso said by email.

However, it's not clear from the study results whether the prognosis is prolonged if people who have never drunk green tea or coffee before start drinking or increase the amount they drink after the onset of cardiovascular disease, Dr. Iso added. The effect of lifestyle changes on prognosis due to the onset of stroke or myocardial infarction is a subject for future research.

Researchers defined a typical cup of green tea as containing approximately 100mL (about 3.4 ounces) of liquid, and a typical cup of coffee as containing approximately 150mL (about 5 ounces) of liquid.

One limitation of the study is that any coffee or green tea consumption, as well as any history of stroke or MI, was self-reported. Researchers also lacked data on any behavior changes over time that might influence cardiovascular outcomes or all-cause mortality.

"In nutritional epidemiology studies like these, we always worry that the observed associations between coffee and tea and mortality may be misattributed to the beneficial health effects of coffee and tea when they may be at least partly due to associated healthy dietary and lifestyle factors among people who consume coffee and tea frequently," said Hannah Gardener, an epidemiologist in the Department of Neurology at the University of Miami Miller School of Medicine.

Patients should always speak with their clinicians about their own specific diet and beverage habits and determine what, if any, changes should be made after a significant vascular event, Gardener, who wasn't involved in the study, said by email. However, the results from this study and previous findings suggest that coffee and tea consumption can be safely included in a healthy diet for the general population.

—Lisa Rapaport

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