Heavy coffee drinking may double risk for CV death in hypertension
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Among adults with hypertension followed for nearly 2 decades, heavy coffee drinking was associated with doubled risk for CV death compared with no coffee drinking, according to data from a large observational study.
In contrast, green tea consumption was not associated with increased risk for CVD mortality across all BP categories.
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“Our study aimed to determine whether the known protective effect of coffee also applies to individuals with different degrees of hypertension and also examined the effects of green tea in the same population,” Hiroyasu Iso, MD, PhD, MPH, director of the Institute for Global Health Policy Research, Bureau of International Health Cooperation, National Center for Global Health and Medicine in Tokyo and professor emeritus at Osaka University, said in a press release. “This is the first study to find an association between drinking two or more cups of coffee daily and CVD mortality among people with severe hypertension.”
Iso and colleagues analyzed data from 18,609 participants in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk, including 12,035 women, who were aged 40 to 79 years at baseline and completed a lifestyle, diet and medical history questionnaire and submitted to regular health exams. Researchers asked participants about their frequency and amount of coffee and green tea consumed using the following choices: almost every day; three to four cups per week; one to two cups per week; one to two cups per month; and almost never. Participants who answered “almost every day” were asked about the number of cups consumed per day. Researchers followed the cohort through 2009 and classified participants into four BP categories: optimal and normal BP (systolic BP < 130 mm Hg and diastolic BP < 85 mm Hg), high-normal BP (systolic BP 130-139 mm Hg or diastolic BP 85-89 mm Hg), grade 1 hypertension (systolic BP 140-159 mm Hg and diastolic BP 90-99 mm Hg), and grade 2 to 3 hypertension (systolic BP 160 mm Hg and diastolic BP 100 mm Hg).
During a median of 18.9 years follow-up, 842 participants died of CV causes.
Researchers found that heavy coffee consumption was associated with increased risk for CVD mortality among people with grade 2 to 3 hypertension. Compared with noncoffee drinkers, HRs for CVD mortality were 0.98 (95% CI, 0.67-1.43) for less than one cup per day, 0.74 (95% CI, 0.37-1.46) for one cup per day and 2.05 (95% CI, 1.17-3.59) for two or more cups per day.
There were no associations between coffee consumption and CV death for people with optimal and normal, high-normal BP and grade 1 hypertension.
Green tea consumption was not associated with an increased risk for CVD across any BP categories, according to researchers.
“These findings may support the assertion that people with severe high BP should avoid drinking excessive coffee,” Iso said in the release. “Because people with severe hypertension are more susceptible to the effects of caffeine, caffeine’s harmful effects may outweigh its protective effects and may increase the risk of death.”
The study found that people with more frequent coffee consumption were more likely to be younger, to be current smokers, to be current drinkers, to eat fewer vegetables, and to have higher total cholesterol levels and lower systolic BP, regardless of BP category.
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