Exclusion diet boosts anal fissure healing

Research published in the American Journal of Gastroenterology shows that an exclusion diet combined with medical treatment can increase healing rates in patients with chronic anal fissure who have been referred for surgery.

Patients in the study were randomly assigned to receive either a sham elimination diet based on the exclusion of rice, potato, lamb, bean, and peas, or a true elimination diet, in which they excluded cow's milk and its derivatives, wheat, egg, tomato, and chocolate - foods the authors had found most commonly caused symptoms in patients with chronic constipation due to food hypersensitivity.

Over 8 weeks, patients also received treatment with sitz baths and bran supplementation (20 g/day), and applied a topical analgesic three times daily.

Among 161 patients, rates of chronic anal fissure healing were higher in the true elimination diet group than in the sham elimination group from week 4 onwards, such that at the end of the study they had reached 69% and 45%, respectively.

Additionally, while rates of constipation were high in both groups at the beginning of the study (85.7% overall), patients in the true diet group had a significantly greater number of bowel movements each week than patients in the sham diet group (4.6 vs 3.6).

The researchers, led by Antonio Carroccio (University of Palermo, Italy), also performed a double-blind cow's milk challenge, and a wheat challenge in 60 patients who had healed chronic anal fissures on the true elimination diet. During each challenge, the patients took 6 g casein or xylose placebo per day, and 12 g flour or xylose placebo per day, while continuing the diet for 2 weeks with a 4-week washout period between the challenges.

Overall, seven patients experienced symptom recurrence with both the cow's milk and wheat protein challenge, and six were positive for only the cow's milk challenge. However, all patients became asymptomatic again while continuing the diet during the washout period.

The researchers also found that during the cow's milk challenge, anal sphincter resting pressure significantly increased from baseline in patients with fissure reappearance, but it did not change in patients who did not react to the challenge.

These results support the hypothesis that some patients with anal fissure may have high resting anal pressure due to unrecognized food hypersensitivity, leading to diminished perfusion pressure and ischemic ulceration of anal tissue, the authors conclude.

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