DITERPENE COMPOSITION OF OILS FROM ARABICA AND ROBUSTA COFFEE BEANS AND THEIR EFFECTS ON SERUM-LIPIDS IN MAN

Objectives. The cholesterol-raising effect of boiled coffee is caused by diterpenes from coffee oil. In order to identify the diterpene resp onsible, we analysed the diterpene composition of oils from Arabica (C offea arabica) and Robusta (Coffea canephora robusta) beans and their effects on serum lipids and thyroid function. Design, Subjects, and In tervention. During the first 3-week period of a randomized, cross-over trial, 11 healthy, normolipaemic volunteers received per day either 2 g of coffee oil (n = 5) or placebo oil (n = 6). After a 2-week wash-o ut, the reverse treatments were applied for another 3 weeks. Six subje cts received Arabica oil, supplying 72 mg day(-1) cafestol and 53 mg d ay(-1) kahweol, and five received Robusta oil, which provided 40 mg of cafestol, 19 mg of 16-O-methyl-cafestol, and 2 mg of kahweol per day. Background diets were constant.Results. The average serum cholesterol levels rose by 0.65 mmol L(-1) (13%) on Arabica oil (P < 0.025; 95% C I, 0.21-1.09 mmol L(-1)) and by 0.53 mmol L-l (13%) on Robusta oil (NS ; 95% CI -0.36-1.42 mmol L(-1)). The triglycerides levels rose by 0.54 mmol L(-1) (71%) on Arabica (P < 0.005; 95% CI, 0.22-0.76 mmol L(-1)) and 0.49 mmol L(-1) (61%) on Robusta oil (P < 0.005; 95% CI, 0.30-0.6 8 mmol L(-1)). None of the effects on serum lipids or lipoprotein chol esterol levels was significantly different between Arabica and Robusta oil. Concentrations of serum total and free thyroxine (T-4), triiodot hyronine (T-3), and thyroid-stimulating hormone (TSH) were largely una ffected. Conclusions. Both Arabica and Robusta oil elevated serum lipi d levels; therefore, cafestol must be involved and kahweol cannot be t he sole cholesterol-raising diterpene. The mode of action of coffee di terpenes does not involve induction of hypothyroidism.