Dietary fiber supplementation for fecal incontinence: a randomized clinical trial.

Randomized clinical trial in community-dwelling adults with fecal incontinence of loose or liquid stools in Minnesota, United States, enrolled from 2004 to 2007. Active intervention arms included CMC (ITTA n=53; PPA n=47), gum arabic (ITTA n=50; PPA n=49), and psyllium (ITTA n=54; PPA n=46); participants continued usual diet and activity, and the trial included a baseline run-in period.

Oral dietary fiber was provided in three active regimens: sodium carboxymethylcellulose (CMC), gum arabic, or psyllium. Supplements were delivered in two fruit juice mixtures and two small muffins, with dosing increased by one-third every 2 days during a 6-day titration period and then maintained for 32 days, for a total study duration of 52 days. Average fiber provided was about 16 g/day overall, with gum arabic 16.6 g/day, psyllium 14.6 g/day, and CMC 16.2 g/day.

Psyllium reduced fecal incontinence frequency, gum arabic was not different from placebo, and CMC worsened fecal incontinence. Weekly FI frequency changed from 6.2 to 5.5 with placebo, 4.7 to 6.2 with CMC, 5.3 to 4.3 with gum arabic, and 5.0 to 2.5 with psyllium. The authors concluded that psyllium may help by forming a gel in feces that retains water. FI quality of life did not differ among groups, and psyllium was generally well tolerated.

The trial was relatively small within each active arm and short in duration, limiting assessment of longer-term benefit and safety. Results were specific to community-dwelling adults with loose or liquid fecal incontinence, so generalizability to other fecal incontinence populations is limited. Findings were heterogeneous across fiber types, with benefit for psyllium but worsening with CMC, which complicates interpretation of fiber supplementation as a class.