Daily tea consumption reduces risk ischemic heart disease Chinese adults
Tea consumption and risk of ischaemic heart diseaseLi X, Yu C, Guo Y, et al. - Heart 2017; published online ahead of print
Polyphenols, particularly flavonoids, are ingredients of tea and have antithrombotic and anti-inflammatory properties. They also inhibit oxidative reactions, reverse endothelial dysfunction, and prevent or delay atherosclerosis . Studies evaluating the association between tea consumption and risk of ischemic heart disease (IHD) have resulted in conflicting conclusions [2,3]. However, these studies were small and low-powered.
In this study, the association of regular tea consumption with the risk of IHD was prospectively examined in 0.5 million adults included in the China Kadoorie Biobank (CKB) study [4,5].
- Of 487 375 study participants, 26.3% reported consuming tea almost every day.
- Compared with participants who never consumed tea during the past 12 months, daily tea consumers were more likely to be younger, urban residents, and more likely to smoke tobacco and drink alcohol.
- During a median follow-up of 7.2 years, 24 665 (7.19 cases/1000 person-years) incident IHD cases and 3959 (1.13 cases/1000 person-years) MACE were documented, including 2601 fatal IHD cases and 1358 non-fatal myocardial infarctions (MIs).
- Compared with participants who never consumed tea during the past 12 months, the multivariable-adjusted HRs for IHD were 0.97 (95% CI: 0.94 - 1.00) for those who consumed tea less than daily, and 0.92 (95% CI: 0.87 - 0.97), 0.91 (95% CI: 0.85 - 0.98), 0.92 (95% CI: 0.87 - 0.98) and 0.91 (95% CI: 0.86 - 0.97) for those who consumed 0.1–2.0, 2.1–3.0, 3.1–5.0 and >5.0 g of tea leaves per day, respectively.
- The corresponding HRs for MACE were 0.92 (95% CI: 0.85 - 1.00), 0.83 (95% CI: 0.74 - 0.95), 0.99 (95% CI: 0.85 - 1.15), 0.87 (95% CI: 0.75 - 1.00) and 0.97 (95% CI: 0.84 - 1.11).
- Compared with participants who never consumed tea during the past 12 months, the HRs for all daily consumers were 0.92 (95% CI: 0.88 - 0.95) for IHD and 0.90 (95% CI: 0.82 - 0.99) for MACE.
- The inverse associations of daily tea consumption with both outcomes appeared to be stronger among participants who reported longer years of tea consumption.
- The associations were similar across subgroups stratified according to age, smoking status, alcohol consumption, physical activity and prevalent hypertension (all P values for interaction >0.05).
- Significant differences in association with IHD and MACE across strata were observed for the region (P values for interaction: 0.006 for IHD and <0.001 for MACE), with stronger inverse associations among participants who resided in rural regions.
- Stronger inverse associations were also observed among participants with BMI <24 kg/m2 for MACE (P value for interaction: 0.012) and those without diabetes at baseline for IHD (P value for interaction: 0.004).
In a large prospective cohort of Chinese adults, daily tea consumption was associated with 8% relative risk reduction in IHD, compared to never drinking tea. These findings confirm the protective effect of tea consumption on IHD.