Coffee, tea, caffeine, and risk of hypertension: The Singapore Chinese Health Study

Eur J Nutr. 2018 Jun;57(4):1333-1342. doi: 10.1007/s00394-017-1412-4. Epub 2017 Mar 1.

Abstract

Purpose: The relationship between coffee and tea, and risk of hypertension remains controversial in Western populations. We investigated these associations in an Asian population.

Methods: The Singapore Chinese Health Study is a population-based prospective cohort that recruited 63,257 Chinese aged 45-74 years and residing in Singapore from 1993 to 1998. Information on consumption of coffee, tea, and other lifestyle factors was collected at baseline, and self-reported physician-diagnosed hypertension was assessed during two follow-up interviews (1999-2004, 2006-2010).

Results: We identified 13,658 cases of incident hypertension after average 9.5 years. Compared to those who drank one cup of coffee/day, the hazard ratios (HR) and 95% confidence intervals (CI) were 0.87 (0.83-0.91) for <weekly drinkers and 0.93 (0.86-1.00) for ≥3 cups/day drinkers. Compared to <weekly drinkers, daily drinkers of black or green tea had slight increase in risk, but these risk estimates were attenuated and became non-significant after adjustment for caffeine. After adjusting for coffee, there was a stepwise dose-response relationship between caffeine intake and hypertension risk; compared to the lowest intake (<50 mg/day), those in the highest intake (≥300 mg/day) had a 16% increase in risk; HR 1.16, 95% CI 1.04-1.31 (p trend = 0.02).

Conclusions: Drinking coffee <1 cup/week or ≥3 cups/day had lower risk than drinking one cup/day. Caffeine may account for increased risk in daily tea drinkers and in those who drank one cup of coffee/day. The inverse U-shaped association with coffee suggests that at higher doses, other ingredients in coffee may offset the effect of caffeine and confer benefit on blood pressure.

Keywords: Caffeine; Coffee; Hypertension; Prospective study; Tea.

MeSH terms

  • Aged
  • Caffeine / pharmacology*
  • Coffee* / chemistry
  • Female
  • Humans
  • Hypertension / epidemiology*
  • Male
  • Middle Aged
  • Prospective Studies
  • Risk Factors
  • Singapore / epidemiology
  • Tea* / chemistry

Substances

  • Coffee
  • Tea
  • Caffeine