BACKGROUND AND PURPOSE: 

• Studies seem to confirm an association between coffee and reduced rates of chronic disease and cancer 
  • Prospective studies also indicate reduced all-cause and cause-specific mortality 
• Limited data  
  • Research suggests that individuals with particular genetic background related to caffeine metabolism may be at increased risk of cardiovascular disease  
  • Few studies analyze heavy coffee drinking (≥6 cups/d)  
• Loftfield et al. (JAMA Internal Medicine, 2018) sought to determine whether the association between coffee drinking and mortality is altered by genetic caffeine metabolism score

METHODS: 

• Population-based study utilizing the UK Biobank cohort for baseline demographic, lifestyle, and genetic data 
• Follow up questionnaires conducted over 10 years 
• Genetic scores were defined based on expression of SNPs  
  • Known to be associated with blood caffeine metabolite levels  
  • Map near genes that are thought to play a role in caffeine metabolism 
• Primary outcome was all-cause and cause-specific mortality

RESULTS: 

• 498,134 subjects were included in the study 
  • Mean age: 57 years (range, 38-73 years) 
  • 271,019 (54%) were female 
  • 387,494 (78%) were coffee drinkers 
  • 14,225 deaths occurred 
• Coffee drinking was inversely associated with all-cause mortality 
• Using non–coffee drinkers as the reference group 
  • Less than 1 cup: Hazard ratio (HR) 0.94; 95% CI, 0.88-1.01 
  • 1 cup/d: HR 0.92; 95% CI, 0.87-0.97 
  • 2 to 3 cups/d: HR 0.88; 95% CI, 0.84-0.93 
  • 4 to 5 cups/d: HR 0.88; 95% CI, 0.83-0.93 
  • 6 to 7 cups/d: HR 0.84; 95% CI, 0.77-0.92 
  • 8 or more cups/d: HR 0.86; 95% CI, 0.77-0.95 
• Results similar for  
  • Instant, ground, and decaffeinated coffee 
  • Across common causes of death 
  • Regardless of genetic caffeine metabolism score

CONCLUSION: 

• Genetic caffeine metabolism score did not impact the inverse association between coffee and mortality 
• Coffee drinking is inversely associated with all-cause mortality, even for heavy drinkers, regardless of whether or not someone is a slow or fast caffeine metabolizer  
• Authors caution that while data is observational and does not imply or prove causation:

Nevertheless, these results provide further evidence that coffee drinking can be part of a healthy diet and may provide reassurance to those who drink coffee and enjoy it.

Learn More – Primary Sources: 

Association of Coffee Drinking With Mortality by Genetic Variation in Caffeine Metabolism – Findings From the UK Biobank 

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