Both Arabica and Robusta oil elevated serum lipid levels; therefore, cafestol must be involved and kahweol cannot be the sole cholesterol-raising diterpene. The mode of action of coffee diterpenes does not involve induction of hypothyroidism.

Boiled coffee contains the lipid compounds cafestol and kahweol, which raise cholesterol strongly in man. These lipids are retained by paper filters. In a search for an animal model for the effect of coffee lipids on serum cholesterol concentrations, we fed hamsters (Mesocvicetus aurutus) and rats on mash diets consisting of a purified base diet and either boiled water, unfiltered boiled coffee or filtered boiled coffee. After a feeding period of 8 weeks there was no statistically significant effect of unfiltered boiled coffee on serum total cholesterol and triacylglycerol concentrations in either the hamsters or the rats. The level of serum cholesterol did respond predictably to the addition of cholesterol and/or saturated fatty acids to the diet. The lack of effect of unfiltered boiled coffee in the hamsters and the rats, when compared with the previously reported activity in humans, could not be explained by dosage, duration of treatment, mode of administration or by insufficient statistical power. It is concluded that hamsters and rats are insensitive to unfiltered boiled coffee and thus are unsuitable models for investigating its hypercholesterolaemic effect.

Objective: Un®ltered coffee raises serum LDL cholesterol in humans, owing to the presence of the diterpenes cafestol and kahweol. Norwegians with a chronic high intake of un®ltered coffee also had elevated serum levels of lipoprotein(a), an LDL-like particle which is insensitive toward dietary interventions. We now experimentally studied the in¯uence of coffee diterpenes on lipoprotein(a) levels. Design: Four randomised controlled trials. Subjects: Healthy, normolipidemic volunteers. Interventions: Coffee, coffee oil, and pure diterpenes for 4±24 weeks. Main outcome measures: The circulating level of lipoprotein(a). Results: In 22 subjects drinking ®ve to six strong cups of cafetiere coffee per day, the median fall in lipoprotein(a) was 1.5 mg/dL after two months (P 0.03), and 0.5 mg/dL after half a year (P b 0.05), relative to 24 ®lter coffee drinkers. Coffee oil doses equivalent to 10±20 cups of un®ltered coffee reduced lipoprotein(a) levels by up to 5.5 mg/dL (P`0.05) in two separate trials (n 12±16 per group). A puri®ed mixture of cafestol and kahweol, as well as cafestol alone, were also effective in reducing Lp(a) levels (n 10). Averaged over the four trials, each 10 mg/d of cafestol (plus kahweol)Ðthe amount present in two to three cups of cafetiere coffeeÐdecreased Lp(a) levels by 0.5 mg/dL or 4% from baseline values after four weeks (n 63). Conclusions: Coffee diterpenes are among the few dietary exceptions shown to in¯uence serum lipoprotein(a) levels. However, the Lp(a)-reducing potency of coffee diterpenes may subside in the long run, and their adverse side effects preclude their use as lipoprotein(a)-reducing agents.

Oil from coffee beans contains the diterpenes cafestol and kahweol, which greatly elevate cholesterol in humans. Consumption of 0.03 g coffee oil (0.86 mg cafestol and 1.04 mg kahweol)/kg body wt raised serum cholesterol by 1.27 mmol/L in volunteers. We fed coffee oil from this same batch to cebus and rhesus monkeys. Two groups of eight cebus monkeys were fed a purified diet containing 0.5% coffee oil or placebo oil (sunflower plus palm oil, 3:2, wt/wt) for 2 x seven and a half weeks in a crossover design. The daily intake of the coffee oil was 0.18 g (5.13 mg cafestol and 6.21 mg kahweol)/kg body wt, or sixfold that in the human study. Coffee oil did not affect plasma cholesterol or triglyceride concentrations compared with the placebo oil. Two groups of three rhesus monkeys were fed a commercial diet containing either 0.5% coffee oil or 0.5% placebo oil for 2 x 6 wk in a crossover design. The daily intake of coffee oil was 0.20 g (5.70 mg cafestol and 6.90 mg kahweol)/kg body wt. Again, there was no effect of coffee oil on plasma cholesterol or triglyceride concentrations. Contrary to the findings in human studies, coffee oil had no impact on plasma alanine aminotransferase activity in nonhuman primates. The cholesterol-raising effect of diterpenes from coffee oil, present in boiled coffee, seems to be specific for human primates.

Abstract. Urgert R, Weusten-van der Wouw MPME, Hovenier R, Lund-Larsen PG, Katan MB (Department