Skin Patch Testing May Help Identify Foods that Cause Symptoms of Irritable Bowel Syndrome

Researchers from the University of Pennsylvania School of Medicine recently published in the Journal of the American Academy of Dermatology results from a study that looked at whether skin patch testing for allergens can help patients identify specific foods in their diet that may be causing symptoms of irritable bowel syndrome (IBS).

The authors wrote that “the traditional classification of irritable bowel syndrome (IBS) as a functional disorder has been challenged in recent years by evidence of ongoing low-grade gastrointestinal tract inflammation. Inflammation may alter gastrointestinal motility and thus be central to the pathogenesis of IBS. Many foods and food additives are known to cause allergic contact dermatitis.” Thus, they hypothesize that “allergenic foods and food additives may elicit a similar allergic reaction in the gastrointestinal tract, giving rise to symptoms suggestive of IBS.”

To test this, they “performed skin patch testing to common allergenic foods and food additives on individuals with a history of or symptoms suggestive of IBS.” Then they used patch test-guided avoidance diets to determine whether avoidance alleviated IBS symptoms in the test subjects.

Skin patch testing was done on 51 patients to detect allergic reactions to foods such as garlic and onion that can trigger IBS symptoms, as well as for reactions to food additives such as propylene glycol, benzoic acid, and sorbic acid. Thirty participants had a “doubtful or positive” reaction to at least one substance, with 23 agreeing to eliminate that food or substance from their diet for at least one week. After one week, nine patients reported no improvement in IBS symptoms, three reported slight improvement in symptoms, eight reported a moderate improvement in symptoms and three said they had a “great improvement in symptoms.” In all, nearly 60% of participants reported they had “at least some improvement in IBS symptoms when they eliminated those foods from their diet.”

The authors concluded that “Allergic contact enteritis to ingested foods, food additives, or both may contribute to IBS symptoms. Patch testing may be useful in identifying the causative foods.”