Yet Another Coffee Study Says It's OK to Drink Up

Danish researchers conducted a meta-analysis that looked at possible associations between coffee intake and obesity, metabolic syndrome, and type 2 diabetes. They reported finding only a low risk of these conditions in coffee drinkers, but no genetic variance to explain the relationships.

Americans consume coffee at unprecedented rates, generating interest in its health effects. Several meta-analyses have identified inverse relationships between coffee intake and diabetes. A new—and slightly different—meta-analysis has looked at possible associations between obesity, metabolic syndrome, and type 2 diabetes. These Danish researchers report low risk of these conditions in coffee drinkers, but no genetic variance to explain the relationships. Note that Danes have the 4th highest intake of coffee in the world, making them an ideal population in which to investigate coffee intake.

Researchers have associated 5 genetic variants located near the CYP1A1, CYP1A2 and AHR genes with high coffee/caffeine intake. Mendelian randomization studies look at randomly inherited genetic variance to study potential causal associations. In this case, the researchers looked at genes associated with coffee intake in 93,179 individuals in a Mendelian randomization study. They tested 3 premises:

  • Whether high coffee intake is linked to low risk of obesity, metabolic syndrome and type 2 diabetes using observational analyses
  • Whether five genetic variants near the CYP1A1, CYP1A2 and AHR genes are associated with coffee intake
  • If the genetic variants are associated with obesity, metabolic syndrome and type 2 diabetes or their components (ie, weight, lipid profile, etc).

In a final step, they included 78,000 additional individuals to test the genetic association with type 2 diabetes.

Participants with high coffee intake were significantly less likely to develop obesity, metabolic syndrome and type 2 diabetes even though they tended to have higher body mass index, waist circumferences, weights, heights, systolic/diastolic blood pressures, triglycerides and total cholesterol levels. Their glucose levels tended to be lower than non-coffee drinkers. Drinking one cup of coffee or more daily reduced risk of type 2 diabetes by 6%.

Possessing several coffee-intake alleles was associated with 29% higher coffee intake. Possessing a genetic predisposition to drink coffee was not associated convincingly with obesity, metabolic syndrome, type 2 diabetes, or their contributing factors. This study appears ahead of print in the International Journal of Epidemiology.