Food allergy treatment is being heavily researched as food allergies are becoming increasingly common. In 2007 the estimated prevalence of food allergies among school children was 4%, an 18% increase since 1997, while other studies estimate up to 8%. One theory why food allergies are increasing is the hygiene hypothesis. Less exposure to certain microorganisms, cause an “evolved dependence” which leads to immune dysregulation and food allergies.
Other factors could be a change of gut flora with obesity and diet, vitamin D deficiency and route of exposure are possibly implicated. Some food allergies are transient, such as milk and egg and resolve over time. Others such as peanut, tree nut, fish and shellfish allergies have life-long effects. In sensitized individuals symptoms can range from hives to anaphylaxis. The current management involves strict avoidance, but within the last few years food allergy treatment with immunotherapy is being explored. There have been several approaches to food allergy treatment (immunotherapy). Desensitization appears achievable with specific foods allowing the patient to tolerate more allergen quantity. In the following discussion, we explore food allergy treatments being explored now.
Egg and Peanut Oral Immunotherapy
Oral immunotherapy involves the daily ingestion of food to which the patient is allergic, which may be in pill or powder form, although generally it is given in powder form within food. Escalating doses are often consumed in a controlled setting with stable dosing completed at home. Recent studies of egg immunotherapy has shown positive results.
Peanut oral immunotherapy was evaluated and after 1 year, 16 patients who received the treatment were all able to tolerate 5,000 mg of peanut protein. Other similar studies showed 54%, 62% and 84% tolerating the maximum peanut protein ingestion within their studies. Studies are still ongoing about the best way to treat peanut allergic patients.
Peanut Sublingual Immunotherapy
Sublingual immunotherapy is a treatment where allergen extracts are taken by mouth, held under the tongue for several minutes, and then spit out or swallowed. It is currently being used for environmental allergy treatment (i.e. dust, trees, cats, dogs), studies have shown positive results for peanut as well. A recent study showed 70% of those treated were able to tolerate a 10 fold increase in peanut protein from baseline after undergoing treatment.
Peanut Epicutaneous Immunotherapy
Epicutaneous Immunotherapy involves the daily administration to the skin surface of a patch that contains the allergen. Last year, information about Viaskin was presented from a phase 2b study who underwent 1 year of EPIT. Children were able to tolerate greater peanut protein and had improved immunologic responses compared to baseline.
For food allergy treatment, desensitization appear to occur within day to months of starting treatment, allowing the reactive dose threshold to increase among all forms of immunotherapy. The results depend on both daily and total dose of immunotherapy and the length of treatment. There is a lack of uniformity among protocols for initial dosing, build up and maintenance dosing. For food allergy immunotherapy to become mainstream, a consensus dosing protocol will need to be standardized to be used on all patients. For efficacy, OIT appears better than SLIT and SLIT better than EPIT. However, the adverse effects also appear in that order. With OIT, the most common adverse effects are abdominal pain and vomiting, which can limit the patients’ ability to continue therapy. Eosinophilic esophagitis has been reported up to 2.7%. SLIT may be less efficacious but perhaps a cleaner adverse effect profile. It exhibits primarily oropharyngeal adverse effects. EPIT does not cause systemic reactions, but difficulties remain with keeping a daily patch in place and large local reactions are common.
Studies will need to focus on changes specific to the form of immunotherapy, dosing, length of treatment and interval after stopping therapy. More information is needed to guarantee the safety of food allergy treatment before its used in clinical practice. At this time it remains investigational.