From the Guidelines
Food allergy testing has limited utility for patients with chronic nonspecific gastrointestinal complaints and should not be used as a first-line investigation. Instead, clinicians should consider more evidence-based approaches such as evaluating for conditions like irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), or celiac disease 1. For suspected food intolerances, a systematic elimination diet followed by controlled reintroduction of foods under medical supervision is more reliable than allergy testing 1. This approach helps identify specific trigger foods while ensuring nutritional adequacy. The exception would be testing for celiac disease (which requires specific antibody tests and possibly endoscopy) or IgE-mediated allergies with immediate reactions. The reason conventional food allergy tests often mislead in these cases is that many chronic GI symptoms result from non-allergic food intolerances, functional GI disorders, or other mechanisms that aren't detected by standard allergy panels 1. Some key considerations in the diagnostic workup include:
- Evaluating for alarm features such as weight loss, blood in stools, nocturnal diarrhea, unexplained iron deficiency anemia, or a family history of selected organic diseases 1
- Assessing for conditions like pancreatic exocrine insufficiency (PEI), bile acid diarrhea (BAD), or small intestinal bacterial overgrowth (SIBO) in patients with inflammatory bowel disease (IBD) 1
- Considering the use of hydrogen and methane-based breath testing for SIBO or carbohydrate malabsorption leading to diarrhea, bloating, and flatulence 1 Patients should work with gastroenterologists and possibly registered dietitians to develop an appropriate diagnostic and management plan tailored to their specific symptoms. It is essential to prioritize the patient's quality of life, morbidity, and mortality when making diagnostic and treatment decisions, and to avoid unnecessary tests or interventions that may lead to harm or unnecessary dietary restrictions 1.
From the Research
Utility of Food Allergy Testing
- Food allergy testing may be useful in diagnosing chronic nonspecific gastrointestinal complaints, particularly in cases where food intolerances or allergies are suspected 2, 3.
- Studies have shown that patients with irritable bowel syndrome (IBS) and inflammatory bowel diseases (IBD) may have increased IgE-type antibody responses to food allergens, suggesting a possible role for food hypersensitivity in these conditions 2.
- Common food allergens that may trigger symptoms in IBS patients include milk protein, soybean, tomato, peanut, and egg white 2.
- Elimination diets may be effective in improving IBS symptom severity in a subset of patients, suggesting that food hypersensitivity may play a role in the condition 3.
Diagnostic Approach
- A thorough medical history and physical examination are essential in evaluating patients with chronic diarrhea or gastrointestinal complaints 4, 5.
- Laboratory tests, such as blood and stool tests, may be indicated in some cases to rule out underlying conditions or to identify potential causes of symptoms 4, 5.
- Food allergy testing may be considered in patients with suspected food intolerances or allergies, particularly if symptoms persist or worsen despite other treatments 2, 3.
Treatment Options
- Treatment of chronic diarrhea or gastrointestinal complaints depends on the underlying cause, but may include dietary changes, medication, or other interventions 4, 6, 5.
- Patients with IBS or IBD may benefit from a food and beverage intolerance, avoidance diet, which can help to identify and avoid trigger foods 6.
- Empiric antidiarrheal therapy may be used to mitigate symptoms in patients with chronic diarrhea, while more specific treatments are being explored 5.