Professor C Mary Schooling co-authors “Habitual coffee consumption and risk of type 2 diabetes, ischemic heart disease, depression and Alzheimer’s disease: a Mendelian randomization study.”
The Dietary Guidelines for Americans 2015-20 say that “moderate coffee consumption can be incorporated into a healthy dietary pattern,” and “coffee consumption is associated with reduced risk of type 2 diabetes and cardiovascular disease in healthy adults.” However, this advice is based on observational studies which might indicate that coffee has protective effects on health or might indicate that people who happen to drink coffee are healthier for other reasons. In the absence of randomized controlled trials showing the effect of coffee on major diseases, Professor Schooling and colleagues compared the risk of several major diseases by genetically predicted coffee consumption. People genetically more inclined to drink coffee did not have a lower risk of type 2 diabetes, ischemic heart disease, depression or Alzheimer’s disease, which casts doubt on coffee contributing to a healthy diet.
In summary, Professor Schooling says, “Coffee consumption appears to have no effect on type 2 diabetes or ischemic heart disease. Dietary interventions to prevent these complex chronic diseases should be sought elsewhere and future dietary recommendations should be based on high quality evidence.”
Kwok MK, Leung GM, Schooling CM, Habitual coffee consumption and risk of type 2 diabetes, ischemic heart disease, depression and Alzheimer’s disease: a Mendelian randomization study, Sci Rep. 2016 Nov 15;6:36500.