Introduction: Prior studies have suggested a link between diet and Coronary Artery Disease (CAD), but there have been mixed findings on the risks and benefits of coffee and tea consumption. We assessed whether there is an association and dose response between coffee and tea intake on CAD incidence among Veterans.
Methods: Million Veteran Program (MVP) is a national, representative longitudinal study of Veterans for genomic and non-genomic research that combines data from self-reported surveys, electronic health records, and biospecimens. Using food frequency data collected from 2011-2017 and CAD outcomes obtained from electronic health records, we used cox proportional hazard ratios (HR) to evaluate the association of coffee or tea intake with CAD incidence among Veterans with complete data. Follow-up began at the completion of the food frequency survey. Tea and coffee were evaluated separately, with intake categorized as never or less than one cup/month, 1-3 cups/month, one cup/week, 2-4 cups/week, 5-6 cups/week, one cup/day, 2-3 cups/day, 4-5 cups/day, or 6+ cups/day. For tea, the last two categories were combined to obtain stable estimates. Multivariate models were adjusted for known CAD risk factors (age, smoking status, physical activity, and education) and other caffeine use (e.g. tea for coffee). We plan to use restricted cubic splines to assess dose-response relationships.
Results: Among 139,549 participants (90.3% male, mean age 64 ± 12 years), 74.2% consumed 1+ cups of coffee a month and 53.7% consumed 1+ cups of tea a month. During a median follow up of 3.2 years, we observed 4,715 new cases of CAD. Compared to those who drank less than one cup of coffee/month, adjusted HRs (95% CI) for CAD were 1.06 (0.92-1.22) for 1-3 cups/month, 1.09 (0.91-1.29) for one cup/week, 0.96 (0.84-1.10) for 2-4 cups/week, 0.92 (0.81-1.04) for 5-6 cups/week, 0.93 (0.85-1.01) for one cup/day, 0.99 (0.91-1.07) for 2-3 cups/day, 1.05 (0.93-1.19) for 4-5 cups/day, and 1.08 (0.92-1.28) for 6+ cups/day (p-linear trend=0.24). Compared to those who drank less than one cup of caffeinated tea/month, adjusted HRs (95% CI) for CAD were 1.08 (0.99-1.17) for 1-3 cups/month, 1.11 (0.99-1.23) for one cup/week, 1.01 (0.91-1.12) for 2-4 cups/week, 1.03 (0.89-1.17) for 5-6 cups/week, 1.04 (0.93-1.17) for one cup/day, 1.12 (0.98-1.28) for 2-3 cups/day, and 1.27 (1.04-1.58) for 4+ cups/day (p-linear trend=0.14).
Conclusion: While coffee intake was not associated with incidence of CAD, there was an elevated risk of CAD restricted to Veterans consuming 4+ cups of caffeinated tea per day.