The intestinal absorption and metabolism of 385μmol chlorogenic acids following a single intake of 200mL of instant coffee by human volunteers with an ileostomy was investigated. HPLC-MS3 analysis of 0-24h post-ingestion ileal effluent revealed the presence of 274±28μmol of chlorogenic acids and their metabolites accounting for 71±7% of intake. Of the compounds recovered, 78% comprised parent compounds initially present in the coffee, and 22% were metabolites including free and sulfated caffeic and ferulic acids. Over a 24h period after ingestion of the coffee, excretion of chlorogenic acid metabolites in urine accounted for 8±1% of intake, the main compounds being ferulic acid-4-O-sulfate, caffeic acid-3-O-sulfate, isoferulic acid-3-O-glucuronide and dihydrocaffeic acid-3-O-sulfate. In contrast, after drinking a similar coffee, urinary excretion by humans with an intact colon corresponded to 29±4% of chlorogenic acid intake . This difference was due to the excretion of higher levels of dihydroferulic acid and feruloylglycine together with sulfate and glucuronide conjugates of dihydrocaffeic and dihydroferulic acids. This highlights the importance of colonic metabolism. Comparison of the data obtained in the current study with that of Stalmach et al.  facilitated elucidation of the pathways involved in post-ingestion metabolism of chlorogenic acids and also helped distinguish between compounds absorbed in the small and the large intestine.
- Chlorogenic acid
- Metabolic pathway