Abstract
Current understanding of the role of excluding certain foods in the treatment of asthma is still limited. A series of observational studies has been carried out monitoring the levels of food specific IgG antibodies to ovalbumin and β-lactoglobulin, utilising an in-house ELISA in young asthmatic children aged between 2-15 years and adults. The levels of these antibodies were also considered in relation to non-atopic individuals with no personal or family history of atopic conditions. Information from a self-administered comprehensive questionnaire provided additional information on all groups regarding family history of atopy, adverse reactions to foods and customary dietary habits. A wide range of anti-ovalbumin and anti-β-lactoglobulin IgG levels were observed in all asthmatic and non-atopic subjects. In both asthmatic young children and adults with or without other atopic conditions, the specific anti-ovalbumin IgG levels were significantly higher (between P<0.001 and P<0.05), than the non-atopic groups. In contrast, specific anti-β-lactoglobulin IgG levels were significantly higher (P<0.01) in asthmatic young children with other atopic conditions compared with the non-atopic subjects. However, specific anti-β-lactoglobulin IgG levels were significantly higher (P<0.01) in adults with asthma only compared with matched non-atopic subjects. A single blind prospective study was undertaken to examine the effects of dietary eggs and cows’ milk avoidance for 8 weeks in asthmatic children on the signs and symptoms of their asthma. Significantly reduced circulating levels of anti-ovalbumin IgG (P<0.01) and anti-β-lactoglobulin IgG (P<0.05), were observed in these children following the dietary exclusion, indicating compliance on the diet. Other benefits of the dietary intervention included less frequently reported episodes of asthmatic attack and significantly increased (P<0.05) PEFR reading. Undesirable outcomes of the diet intervention included slight weight loss in 7 of 13 children, although this was not statistically significantly different. Evidence from this thesis supports the concept of the role of diet in the induction of the asthmatic condition, together with the role of diet intervention in the treatment of the asthmatic condition.