One (1) RCT (+ quality) found that 1-2 teaspoons Metamucil, composed of psyllium fiber, taken daily during the course of pelvic radiation treatment for prostate or gynecological cancer, was effective in reducing the incidence (p = 0.030) and severity (p = 0.049) of radiation-induced diarrhea (RID).  When data was analyzed excluding the use of anti-diarrheal medications, Metamucil still demonstrated a trend toward effectiveness in decreasing the incidence (p = 0.078) and severity (p = 0.107) of RID, but did not reach statistical significance.   This study was limited by a high dropout rate, mostly due to failure to complete diaries.  Further study is needed to evaluate the role of psyllium fiber in controlling RID.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.