Background & Aims: Conventional bowel cleansers for colonoscopy have an unpleasant taste and a large volume of solution must be ingested. Coffee increases bowel motility and has an intense flavor. The addition of coffee to a polyethylene glycol+ascorbic acid solution reduces the volume of the solution to be consumed without reducing efficacy, improves the taste of the solution and enhances patient comfort.

Methods: Outpatients with clinical indication or people who wanted screening for cancer were considered eligible. Control group (PEGAS group) consumed a 1-L solution of polyethylene glycol+ascorbic acid twice. Study group (COF group) consumed 750 mL of coffee+polyethylene glycol+ascorbic acid twice. Bowel cleansing was rated using the Aronchick, Ottawa scale, polyp detection rate and colonoscopic insertion time. Tolerability, acceptability, preference, and adverse events were investigated by questionnaires.

Results: The COF group had non-inferiority in efficacy (non-inferiority margin, -15 %; lower limit of 95 % confidence interval for difference between success rates, – 4.7 % and –8.4 % from both scales, respectively). Polyp detection rates were 0.48 and 0.60, respectively (P=0.067). Colonoscopic insertion times were 323.6±166.8 s and 330.7±243.6 s, respectively (P=0.831). Significant improvement was observed with respect to ease of drinking (P=0.012), taste (P=0.026) and preference (P=0.046) in the COF group. Adverse events occurred in 52.4 % and 60.4 % in the two groups, respectively (P = 0.251).

Conclusion: The addition of coffee to polyethylene glycol+ascorbic acid solution reduces the required volume for bowel preparation without reduced efficacy and enhances patient comfort in coffee-drinkers.

Abbreviations: ASC: ascorbic acid; PEG: polyethylene glycol; AE: adverse event; PP: per protocol; ITT: intention-to-treat; PICO: sodium picosulfate.


coffee, bowel preparation, polyethylene glycol, ascorbic acid