Effects of coffee and tea on lipoproteins and prostanoids.

The effects of coffee and tea on serum lipoproteins, plasma and urinary prostanoids and thromboxane production by platelets were studied in 12 healthy volunteers aged 33-45 years. They consumed daily, during 3 successive periods of 3 weeks, 8 cups of either instant coffee (16 g/d), instant tea (2.8 g/d) or rosehip 'tea'. The daily dose of coffee yielded 520 mg caffeine, that of tea 200 mg caffeine, while no caffeine was detected in the rosehip 'tea'. No differences were observed between the study periods in the total serum or serum lipoprotein (VLDL, LDL, HDL2, HDL3) cholesterol or triglyceride concentrations. Plasma and serum concentrations and urinary excretion of prostanoids (plasma and urinary TXB2, PGE2 and 6-keto-PGF1 alpha and serum TXB2) remained constant during the three study periods. These results suggest that coffee or caffeine do not exert any detectable effects on serum lipids in healthy normolipidaemic individuals.