Food allergies are on the rise but effective treatment in the pipeline

Experts in the U.S. say food allergies are on the rise and although strict avoidance is currently the only treatment, new effective therapies are currently being developed.

According to experts at the annual meeting of the American College of Allergy, Asthma and Immunology (ACAAI) in Seattle, research shows that food allergies are increasing - especially peanut allergy, which has increased significantly.

Dr Sami Bahna, a professor of paediatrics & medicine and chief of Allergy & Immunology, Louisiana State University Health Sciences Centre, says in the United States, food allergies are now estimated at 3.7% in adults and 6% in children.

Dr. Bahna says allergies and asthma are increasing, and the main manifestations of food allergy are increasing, including atopic dermatitis, anaphylaxis, and eosinophilic gastrointestinal disorders.

He says random phone interviews in 2002 showed peanut and tree nut allergy in the general population to be 1.2%, double that of a similar survey in 1997.

Dr. Bahna blames the increasing causes of food allergy to the increase in:

• Food consumption and obesity, including the highly allergenic foods fish, peanut, tree nuts, milk, egg and soy.

• Eating out, and the prevalence of buffet restaurants and "all you can eat."

• Food varieties and food cross-reactivities with non-ingestant allergens, such as latex, cockroach, dust mite and pollen.

• Commercial foods incorporating multiple nutrient and non-nutrient allergenic ingredients and the incorporation of food proteins in medical diagnostic and therapeutic agents particularly dermatologic.

According to Dr. Bahna, factors that seem to contribute to the increase in food allergy include the high survivorship of atopic subjects allowing the spread of the genetic traits; the hygiene hypothesis; caesarean section deliveries; use of antacids; and use of infant multivitamins.

He says reactions to food allergy can be severe and even fatal and current treatments are strict avoidance of the offending food, which is very difficult to accomplish, and treating reactions as they occur.

Dr Robert A. Wood, a professor of paediatrics and international health, and director of Paediatric Allergy and Immunology at Johns Hopkins University School of Medicine in Baltimore, says there are currently three approaches to the treatment of food allergy in development: anti-IgE antibodies, Chinese herbal remedy and immunotherapy.

Dr Wood says anti-IgE therapy at the highest dose would protect most patients from reactions due to accidental exposures, but it is a medicine, not a vaccine, and it must be given on a continuous basis and although it could be used for any food allergy, it doesn't work if patients are too allergic, and there are also concerns about its safety and cost.

The first clinical trial for food allergy was recently initiated with Chinese herbal formula FAHF-2 where studies in mice showed allergic reactions on a variety of measures of peanut allergy were markedly reduced and no side effects were seen.

Dr Wood says immunotherapy induces tolerance to an allergen by giving gradually increasing doses of the allergen and in food allergy, the risks of traditional immunotherapy have far outweighed the benefits, but new approaches may change this equation.

There have been several preliminary studies on oral or sublingual immunotherapy for food allergy with very encouraging results and strong evidence of at least short term desensitization - preliminary research has also found that modified allergens, including peptide vaccines and mutated recombinant vaccines, may be promising new treatments.

The Food Allergy Research Consortium, which is sponsored by the National Institutes of Health, is dedicated to the study of food allergy and has five years of initial funding.

Three studies are already underway - an observational study of infants with eczema and food allergy - oral egg immunotherapy and a sublingual peanut immunotherapy study.

A fourth study on recombinant peanut vaccine safety study is currently being developed.

Dr. Wood says progress will be slow, but a truly effective treatment for severe, persistent food allergy will be developed in the next 10-20 years.

Food allergy is the single leading cause of anaphylaxis, the most severe form of allergic reactions, affecting multiple organ systems.

Symptoms can include chest tightness, wheezing, nausea, vomiting, cramping, hives and swelling of the lips and joints but the most dangerous symptoms are breathing difficulties, throat swelling, chest wheezing, dizziness, low blood pressure, shock and loss of consciousness, all of which can be fatal.

Patients with severe reactions should have continued access to self-administered epinephrine injections.