Heavy consumption (2 or more cups/day) of coffee but not green tea among subjects with severe hypertension (Grade 2 and 3; blood pressure [BP] ≥160/100 mmHg) resulted in doubling of the risk of cardiovascular disease (CVD) mortality compared to those with normal or high normal BP and Grade 1 hypertension, as per the results of a recent study published in the Journal of the American Heart Association.
This large long-term cohort study included 18,609 participants (aged 40–79 years) from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC), with an aim to examine the effect of green tea or coffee consumption on the risk of CVD mortality across multiple BP categories. The study participants completed a self-administered survey questionnaire on demographics, medical history, lifestyle, and diet, including frequency and amount of coffee and green tea consumption. Blood pressure was measured at baseline and the participants were categorized into four groups, viz., optimal and normal BP, high-normal BP, Grade 1 hypertension, and Grade 2–3 hypertension.
Over a median follow-up period of 18.9 years, 842 CVD deaths were reported.
- Among subjects with Grade 2–3 hypertension, ≥2 cups/day was associated with a higher risk of CVD mortality compared to those who did not consume coffee (see the graphic below).
- No significant risk of CVD mortality was noted in participants with optimal and normal BP, high-normal BP, and Grade 1 hypertension among people who consumed coffee (see the graphic below).
- Green tea consumption was not associated with CVD mortality risk in any BP category (see the graphic below).
Clinical implication:
- The results of this study imply that patients with severe hypertension should avoid high coffee intake.
- Coffee exerts beneficial cardiovascular effects by virtue of its components like chlorogenic acid and other phenolic compounds, which possess anti-inflammatory effects, lipid-lowering effects, and beneficial endothelial effects.
- Caffeine in coffee can cause transient acute BP elevation. Tolerance develops to this effect among habitual coffee drinkers.
- However, people with severe hypertension are more susceptible to the acute effects of caffeine, which may offset the beneficial effects of other components. Thus, they have a higher risk for CVD mortality with heavy coffee consumption.
- On the contrary, green tea (which also contains caffeine) was not associated with increased risk of CVD mortality. This can be explained to some extent by the presence of catechins in green tea, which lowers BP, oxidative stress, lipids, and inflammation.
(Reference: Teramoto M, Yamagishi K, Isao Muraki I, et al. Coffee and green tea consumption and cardiovascular disease mortality among people with and without hypertension. J Am Heart Assoc. 2022;11:e026477. Doi: 10.1161/JAHA.122.026477)