The Effect in Volunteers of Coffee and Decaffeinated Coffee on Blood Glucose, Insulin, Plasma Lipids and Some Factors Involved in Blood Clotting

Abstract

The effect of coffee-drinking on blood composition was studied in 20 healthy volunteers who normally consumed, on average, 560 mg caffeine/day from tea and coffee. After 14 days on decaffeinated coffee (12 mg caffeine/day) there was a reduction in blood glucose, a small rise in plasma cholesterol and phospholipid, and a more substantial fall in triglycerides. The substitution of coffee for decaffeinated coffee (875 mg caffeine/day) for 20 days did not affect blood glucose, but the changes in the plasma lipids were reversed. There was no change in the level of immunoreactive insulin, in platelet adhesiveness, fibrinogen or blood clot lysis time during the course of the experiment. The part played by caffeine and by coffee solids other than caffeine in the induction of these changes does not support the hypothesis that the consumption of coffee is a significant factor in the development of coronary heart disease.