Research has linked drinking coffee to a reduced risk of developing type 2 diabetes; what’s unknown, however, is the mechanism for this association. Non-alcoholic fatty liver disease (NAFLD) characterizes and predicts type 2 diabetes, yet the relationship of coffee with this disorder remains unclear. So, Canadian researchers investigated the associations of coffee with markers of liver injury in 1,005 multi-ethnic, non-diabetic adults in the Insulin Resistance Atherosclerosis Study (BMC Gastroenterol. 2015;15(1):88).

Caffeinated coffee showed significant inverse associations with alanine aminotransferase and aspartate aminotransferase (liver enzymes) and NAFLD liver fat score, but not with fetuin-A. When the highest alcohol consumers were excluded, these associations remained. With additional adjustment for insulin sensitivity, the relationship with alanine aminotransferase remained significant. There were no significant associations of decaffeinated coffee with liver markers.

Their analyses indicate a beneficial impact of caffeinated coffee on liver morphology and/or function, and suggest this relationship may mediate the well-established inverse association of coffee with risk of type 2 diabetes.