Tools for Practice


#74 Coffee: Advice for our Vice?


CLINICAL QUESTION
Does drinking coffee impact mortality or other health outcomes in the general population?

BOTTOM LINE
Coffee consumption is associated with a possible small reduction in mortality in cohort studies. While the evidence is not strong enough to recommend non-drinkers to start consuming coffee, coffee drinkers can be reassured that it does not result in harm (except in pregnancy).


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EVIDENCE
Meta-analysis1 of 21 cohort studies including 997,464 people in US, Europe or Japan 
  • Largest included cohort study2 followed 402,260 people in US (age 50-71 years) for 14 years 
    • Drinking coffee was associated with several confounders (more likely to smoke cigarettes, drink alcohol, be physically inactive, and have poor diet) 
  • After adjusting for confounders, coffee drinkers (compared to those that did not drink coffee), had a statistically significant lower risk of overall mortality: 
    • About 15% relative risk reduction for 2-3 cups/day 
    • No dose-response relationship; risk was similar whether individuals drank 1 or 8 cups/day 
  • Cardiovascular deaths decreased, deaths due to cancer were unchanged. 
Other meta-analyses3,4 (including one of 36 observational studies of 1,279,804 individuals3) found similar results for cardiovascular events and mortality. Context:  
  • Decaffeinated coffee seems to convey similar health benefits, so the benefit may not be due to caffeine.2 
  • Similar evidence for drinking tea.5 
  • Evidence is from cohort studies, and therefore can only show association (not causation) with reduced mortality 
    • Unfortunately, a large randomized controlled trial is unlikely 
    • However, this evidence seems to rule out clinically important harm. 
  • Cancer rates: Some research suggests coffee consumption is associated with reduced rates of some cancers,6,7 while other studies find no association.7-10 
  • Coffee intake is also associated with a reduced risk of diabetes11 and depression.12 
  • Coffee use in pregnancy (particularly >4 cups/day) increases the risk of fetal loss.13 Pregnant women should be advised of this potential risk. 
October 1, 2012

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Author(s):

  • G. Michael Allan MD CCFP
  • Marco Mannarino MD CCFP

1. Crippa A, Discacciati A, Larsson SC, Wolk A, Orsini N. Am J Epidemiol 2014;180:763-75.

2. Freedman ND, Park Y, Abnet CC, et al. N Engl J Med 2012;366:1891-904.

3. Ding M, Bhupathiraju SN, Satija A, van Dam RM, Hu FB. Circulation 2014;129:643-59.

4. Zhao Y, Wu K, Zheng J, Zuo R, Li D. Public Health Nutrition 2014;18:1282-91.

5. Zhang C, Qin Y-Y, Wei X, Yu F-F, Zhou Y-H, He J. Eur J Epidemiol 2015;30:103-13.

6. Yu X, Bao Z, Zou J, et al. BMC Cancer 2011;11:96.

7. Turati F, Galeone C, La Vecchia C, et al. Ann Oncol 2011;22:536-44.

8. Park C-H, Myung S-K, Kim T-Y, et al. BJU Int 2010;106:762-9.

9. Turati F, Galeone C, Edefonti V, et al. Ann Oncol 2012;23:311-8.

10. Zhang X, Albanes D, Beeson WL, et al. J Natl Cancer Inst 2010;102:771–83.

11. Huxley R, Lee CMY, Barzi F, et al. Arch Intern Med 2009;169:2053-63.

12. Grosso G, Micek A, Castellano S, Pajak A, Galvano F. Mol Nutr Res 2016;60:223-34.

13. Li J, Zhao H, Song JM, Zhang J, Tang YL, Xin CM. Int J Gynaecol Obstet 2015;130:116-22.

Authors do not have any conflicts of interest to declare.