By: Dr. Geoffrey Modest
A Korean observational study looked at the relationship between coffee consumption and coronary artery calcium (CAC) found on cardiac CT scan, a marker of coronary atherosclerosis and pretty good predictor of future clinical coronary artery disease, or CAD (see doi.org/10.1136/heartjnl-2014-306663). In this study 25,130 youngish men and women (mean age 41.3, 83% male) without clinically evident CAD were followed in the Kangbuk Samsung Health Study with annual or biennial examinations (including a detailed, validated food frequency questionnaire) between March 2011 and April 2013. These exams are mandatory in Korea for all workers, and CAC screening there is common practice.
–the largest group consumed 1-<3 cups coffee/d, and overall mean of 1.8 cups/d.
–those who consumed the highest amounts of coffee tended to be older, male and current smokers, with higher education, less physical activity, more obesity and hypercholesterolemia. Higher consumers also had increased fasting glucose, HbA1C, total cholesterol, triglycerides, LDL, higher consumption of total energy, red and processed meats, alcohol, and they also had lower HDL, systolic BP, and lower consumption of fruits and vegetables [ie, those drinking more coffee overall had worse health parameters, mostly in a dose-response manner]
–13.4% had CAC scores >0, with 11.3% having scores 1-100 and 2.1% >100
–CAC ratios comparing coffee drinkers of <1, 1-<3, 3-<5, and >=5 cups/day to non-drinkers were respectively:
–0.86 (0.55-1.38), 0.82 (0.53-1.26), 0.78 (0.50-1.22), 1.77 (0.66-2.06) in model controlled for age, sex, year and site of screening, with p=0.20 for trend
–0.77 (0.49-1.19), 0.66 (0.43-1.02), 0.59 (0.38-0.93), 0.81 (0.46-1.43) in model controlled for above plus education, physical activity, smoking, BMI, fam hx CAD, alcohol, diet (fruit/vege, red meat), with p=0.02 for trend. simliar numbers if further adjustment for SBP, fasting glucose, total cholesterol, triglycerides and HDL.
–0.90 (0.74-1.10), 0.85 (0.71-1.03), 0.80 (0.66-0.97), 0.94 (0.73-1.20) in multiple logistic regression model with p=0.02 for trend
So, a pretty strong association, which was basically U-shaped (with increased CAC in non-drinkers and heavy-drinkers). This is basically in alignment with other studies, showing moderate coffee consumption is associated with less CAD. Physiologic studies have found that coffee consumption is associated with improved endothelial function, lower risk of diabetes, improved insulin sensitivity and b-cell function (?related to anti-oxidants in the coffee, eg phenolic compounds), and decreased inflammatory markers. There are, of note, potential differences with how coffee is prepared (eg, unfiltered coffee seems to raise LDL levels). Although this study did not differentiate regular vs decaffeinated coffee, the latter is not consumed much in Korea. Of course, these types of studies are observational and do not prove causality, but they at least give some reassurance that moderate coffee consumption is not bad, even though the coffee-consumers overall had increasingly bad lifestyle parameters as noted above.
Prior blogs have noted that chocolate is associated with deceased CAD, stroke, diabetes and metabolic syndrome (see doi: 10.1136/bmj.d4488), improves cognition, improves walking distance in those with peripheral arterial disease, and in countries with the highest per-capita chocolate consumption, produces the most nobel laureates (see N Engl J Med 2012: 367;16).
So, what does this all mean? Probably that it is good that I drink coffee every morning, but that I should consider mocha as a more healthy alternative…