Dose-dependent absorption of chlorogenic acids in the small intestine assessed by coffee consumption in ileostomists

Scope Until now, the question of how the ingested doses of chlorogenic acids (CGA) from coffee influence their absorption and metabolism remains unresolved. To assess absorption in the small intestine, we performed a dose-response study with a randomized, double-blinded, crossover design with ileostomist subjects. Methods and results After a polyphenol-free diet, the volunteers consumed, on three separate occasions, coffee with different total CGA contents (high 4525 mu mol; medium 2219 mu mol; low 1053 mu mol). CGA concentrations in plasma, ileal effluent, and urine were subsequently determined by HPLC-DAD-ESI-MS and -ESI-MS/MS. The results show that the consumption of higher CGA concentrations leads to a faster ileal excretion. This corresponds to a renal excretion of 8.0 +/- 4.9% (high), 12.1 +/- 6.7% (medium), and 14.6 +/- 6.8% (low) of total CGA and metabolites. Glucuronidation of CGA became slightly greater with increasing dose. After enzyme treatment, the area under the curve (AUC)08h for CGA metabolites in plasma was 4412 +/- 751 nM x h08-1 (high), 2394 +/- 637 nM x h08-1 (medium), 1782 +/- 731 nM x h08-1 (low), respectively. Additionally, we were able to identify new metabolites of CGA in urine and ileal fluid. Conclusion We conclude that the consumption of high CGA concentrations via coffee might influence the gastrointestinal transit time and consequently affect CGA absorption and metabolism.