Allergenicity of common foods restricted in respiratory allergy

Although hypersensitivity to foods is often linked to exacerbations of symptoms of respiratory allergy, no such information is available regarding the foods traditionally considered to play a probable etiological role in respiratory allergy in India, which are in fact quite different from the ones implicated in the West. The present study was undertaken to investigate whether the practice of withholding certain common foods by parents and practitioners of indigenous systems of medicine (i.e. Ayurvedic and Unani systems of medicine) in children suffering from respiratory allergy had any scientific basis or explanation as judged by modern techniques of investigation. Skin prick tests were performed on 64 children with symptoms pertaining to respiratory allergy (32 each in study and control group) using crude antigenic food extracts. Oral food challenges were administered to children to confirm or rule out allergenicity of food (s) incriminated on the basis of the clinical history and/or a positive skin test. Parental history of food restriction alone, in absence of positive skin prick test was of little value in predicting a positive response to the food challenges (1 challenge positive out of 77 based on food restriction: 1.29%). Only 27.02% and 18.75% of positive skin tests were found to be clinically significant in study and control groups respectively. Traditionally, food beliefs were upheld in only 12.5% children for immediate onset clinical reactions (with 5.31% of the foods restricted in their diet) and 9.37% children for delayed onset clinical reactions (with 3.19% of the foods restricted in their diet). The present study shows that even though food restriction is a common practice in patients with respiratory allergy in India, objective documentation of Type I reactions due to these foods cannot be obtained in a majority of such children.