High coffee intake associated with cardiovascular mortality in hypertensive subjectsThank you for reading this post, don't forget to subscribe!
A study published in Journal of the American Heart Association described that excessive coffee consumption may increase the risk of cardiovascular disease-related mortality in people with severe hypertension.
study: Coffee and green tea consumption and cardiovascular disease mortality among people with and without hypertension. Image credit: Bogdan Malitski / Shutterstock
Coffee consumption is known to reduce the risk of hypertension and associated mortality in the general population. However, it can cause a transient increase in blood pressure in people with hypertension.
Evidence suggests that the beneficial effect of coffee consumption depends on individuals’ blood pressure levels. In patients with severe hypertension, coffee can cause a sharp increase in blood pressure, increasing the risk of cardiovascular disease.
On the other hand, green tea consumption is known to reduce blood pressure in hypertensive patients. In addition, green tea reduces the risk of all-cause mortality and cardiovascular disease-related mortality in the general population.
In the current study, scientists investigated the relationship between coffee or green tea consumption and the risk of cardiovascular disease-related mortality in Japanese men and women with varying degrees of hypertension.
I study design
A total of 18,609 people, including 6,574 men and 12,035 women, from 24 communities in Japan were included in the study. Participants were asked to complete questionnaires to collect information on demographic characteristics, medical history, lifestyle, and diet.
Participants’ baseline blood pressure was measured by trained personnel. Based on blood pressure levels, participants were categorized into five groups, including optimal and normal blood pressure, high normal blood pressure, grade 1 hypertension, grade 2 hypertension, and grade 3 hypertension.
The study examined the relationship between the degree of coffee consumption and baseline characteristics of participants belonging to each blood pressure category. Higher rates of coffee consumption were observed among younger participants, current smokers, current drinkers, and lower vegetable eaters. In addition, participants with higher levels of total cholesterol and lower systolic blood pressure were also likely to drink coffee more often.
The study also examined the relationship between the degree of green tea consumption and baseline characteristics of the participants in each blood pressure category. Higher rates of green tea consumption were observed among older participants, frequent fruit eaters, and working participants.
An association between higher green tea consumption and lower total cholesterol levels was observed among participants with grade 2-3 hypertension.
Coffee consumption and risk of cardiovascular disease mortality
A total of 842 deaths related to cardiovascular disease occurred during the 18.9 years of follow-up.
Consumption of two or more cups of coffee per day was found to increase the risk of cardiovascular disease-related mortality among participants with stage 2-3 hypertension. In contrast, no such association was observed among participants with optimal and normal blood pressure, high normal blood pressure, or grade 1 hypertension.
Green tea consumption and risk of cardiovascular disease mortality
Green tea consumption was not found to increase the risk of cardiovascular disease-related mortality among participants with stage 1 to 3 hypertension.
Among participants with high-normal blood pressure or optimal/normal blood pressure, consumption of 5-6 cups or 1-2 cups of green tea per day, respectively, slightly reduced the risk of cardiovascular disease-related mortality.
Green tea. Image credit: Den Edryshov / Shuuterstock
Significance of the study
The study revealed that a high level of coffee consumption could lead to a 2-fold induction of the risk of cardiovascular disease-related mortality among individuals with severe hypertension, but not among individuals without hypertension or stage 1 hypertension.
The study could not find any negative effect of green tea consumption on the risk of cardiovascular disease-related mortality among individuals with mild or severe hypertension.
Certain components of caffeinated coffee, including chlorogenic acid, magnesium, and trigonelline, are known to have health benefits, including reduced blood cholesterol levels, inflammation, and improved endothelial function. These positive effects eliminate the negative cardiovascular effects of caffeine in the general population.
Given the current study findings, scientists suggest that the higher sensitivity of people with severe hypertension to the adverse effects of caffeine may actually offset its health benefits and increase the risk of death.
Caffeinated green tea, on the other hand, contains a high level of polyphenols, including epigallocatechin gallate. Polyphenols have several health benefits, including anti-inflammatory, antioxidant, lipid-lowering, and blood pressure-lowering properties. The positive health effects of the catechins in green tea are enough to cancel out the negative cardiovascular effects of caffeine.
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