The effect of unfiltered coffee on potential biomarkers for colonic cancerrisk in healthy volunteers: a randomized trial

Background: Epidemiologic studies suggest that coffee use might protect aga inst colorectal cancer. Inconsistencies as to the effect of coffee use and colorectal cancer between epidemiologic studies might be related to the typ e of coffee brew. Objective: We studied the effect of unfiltered coffee consumption on putati ve biomarkers for colonic cancer risk. Design: A total of 64 healthy volunt eers (31 men and 33 women), with a mean age of 43 +/- 11 years were randoml y assigned to two groups in a crossover design, with two intervention perio ds of 2 weeks separated by a washout period of 8 weeks, Treatments were 1L of cafetiere (French press) coffee daily or no coffee, At the end of each i ntervention period, fasting blood samples, colorectal biopsies and 48 h fae ces were collected. Results: No effect of coffee on colorectal cell proliferation, assayed by e stimating the Proliferating Cell Nuclear Antigen labelling index, was seen, Additionally, no effects were seen on the concentrations of faecal soluble bile acids and colorectal mucosal glutathione S-transferase activity. Howe ver, unfiltered coffee significantly increased the glutathione content in t he colorectal mucosa by 8% and in plasma by 15%. Other aminothiols in plasm a also increased on coffee. Conclusion: Unfiltered coffee does not influence the colorectal mucosal pro liferation rate, but might increase the detoxification capacity and anti-mu tagenic properties in the colorectal mucosa through an increase in glutathi one concentration, Whether this effect indeed contributes to a lower colon cancer risk remains to be established.