Wheat bran is commonly recommended as a dietary fiber supplement to support the management of anal fissures and, to a lesser extent, anal fistulas. The justification for its use is primarily scientific, based on its well-documented ability to increase stool bulk and soften stool consistency. This effect reduces straining during defecation, which is a key factor in both the prevention and healing of anal fissures. Multiple clinical guidelines for the management of anal fissures, including those from the American Society of Colon and Rectal Surgeons, recommend a high-fiber diet — and wheat bran is specifically mentioned as a fiber source in several clinical studies and reviews. Meta-analyses and randomized controlled trials have shown that increased dietary fiber intake can significantly improve healing rates for acute anal fissures and reduce symptoms such as pain and bleeding.

For anal fistulas, the evidence is less direct. While fiber supplementation (including wheat bran) does not heal fistulas, it can ease symptoms by normalizing bowel movements and preventing constipation, thereby minimizing trauma to the anorectal area during healing or after surgery. There is little evidence that wheat bran has any direct effect on the fistula tract itself, but its use is still commonly advised as part of broader supportive care.

In summary, wheat bran is supported by moderate scientific evidence (rating: 3/5) for the management of anal fissures, largely as a well-tolerated and effective fiber supplement to improve bowel function, but its role in anal fistula management is supportive rather than curative.