Cafestol and Kahweol
Coffee consumption has been associated with higher serum total and LDL cholesterol concentrations in some observational studies but not others. 11 The observation that the positive association between coffee consumption and serum cholesterol was more consistent in Scandinavia, where boiled coffee was popular at the time, than in other European countries and the US, where filtered coffee was more popular, led to the hypothesis that the brewing method was critical to the cholesterol-raising effect of coffee. 12 A meta-analysis of 14 randomized controlled trials examining the effect of coffee consumption on serum cholesterol concentrations found that the consumption of boiled coffee dose-dependently increased serum total and LDL cholesterol concentrations, while the consumption of filtered coffee resulted in very little increase in serum cholesterol. 13 The cholesterol-raising factors, first isolated in coffee oil, were later found to be the diterpenes, cafestol and kahweol (Figure 3). 12 These diterpenes are extracted from ground coffee during brewing, but are mostly removed from coffee by paper filters. Scandinavian boiled coffee, Turkish coffee, and French press (cafetiere) coffee contain relatively high levels of cafestol and kahweol (6–12 mg/cup), while filtered coffee, percolated coffee, and instant coffee contain low levels of cafestol and kahweol (0.2–0.6 mg/cup). 14 , 15 Although diterpene concentrations are relatively high in espresso coffee, the small serving size makes it an intermediate source of cafestol and kahweol (4 mg/cup). Studies in ileostomy patients indicate that about 70% of the cafestol and kahweol in unfiltered coffee is absorbed intestinally. 16 The mechanisms for the effects of these diterpenes on lipoprotein metabolism are not yet clear, but consumption of cafestol and kahweol in French press coffee has been found to result in persistent increases in cholesterol ester transfer protein (CETP) activity in humans, which may contribute to increases in LDL cholesterol. 17 CETP transfers cholesteryl esters from HDL to the apolipoprotein B-containing lipoproteins, LDL and VLDL.