Absorption and urinary excretion of the coffee diterpenes cafestol and kahweol in healthy ileostomy volunteers.

Abstract

OBJECTIVES: To determine the absorption and urinary excretion of the cholesterol-raising coffee diterpenes cafestol and kahweol in humans. SUBJECTS AND DESIGN: Nine healthy ileostomists consumed a dose of one, two or three cups of French-press coffee together with a standardized breakfast on three separate days in random order. Subsequently, ileostomy effluent was collected for 14 h and urine for 24 h. Stability of cafestol and kahweol was also assessed under simulated gastrointestinal tract conditions. MAIN OUTCOME MEASURES: Absorption of diterpenes, stability of diterpenes during incubation with gastrointestinal fluids, and urinary excretion of diterpenes. RESULTS: Corrected mean absorptions expressed as percentages of the amount consumed and the amount entering the duodenum were 67 and 88%, respectively, for cafestol, and 72 and 93%, respectively, for kahweol. We found losses of diterpenes during incubation in vitro with gastric juice (cafestol, 24%; kahweol, 32%), during storage with ileostomy effluent (cafestol, 18%; kahweol, 12%), and during freeze-drying (cafestol, 26%; kahweol, 32%). Mean excretion of glucuronidated plus sulphated conjugates in urine was 1.2% of the ingested amount for cafestol and 0.4% of the ingested amount for kahweol. CONCLUSIONS: About 70% of the ingested cafestol and kahweol is absorbed in ileostomy volunteers. Possibly, undetected metabolites are present in ileostomy effluent, resulting in lower absorption percentages. Only a small part of the diterpenes is excreted as a conjugate of glucuronic acid or sulphate in urine. Therefore, these compounds are extensively metabolized in the human body.