LONDON – Food allergy is most commonly linked to hen’s eggs in Berlin, breastfeeding protects against the development of asthma, and both asthma and atopic disease are not one but several related conditions.
These are just a few of the recent findings obtained from European birth cohort studies, and reported at the Excellence in Paediatrics annual meeting.
“Birth cohort studies provide an opportunity to examine the effects of environmental influences on child health and development,” said Dr. Giorgio Tamburlini, research director at the Institute of Child Health (IRCCS) Burlo Garofolo in Trieste, Italy. Such studies also allow complex interactions between genes and the environment to be explored.
Over the past 2 decades, interest has grown in the performance of large, longitudinal studies of pregnant women and their newborn babies. This stems from “mounting evidence that many diseases and conditions have causes that start shortly after conception,” Dr. Tamburlini observed. “Factors that influence early organ and system development may have profound effects on health during childhood, as well as during later life.”
Food allergy is an increasingly common problem among young children, and data from EuroPrevall have started to provide much needed information on its prevalence and causes. The project started in 2005 and ended in December 2009. Early findings obtained at the Charité University Medical Center Berlin – one of the many centers contributing to the EuroPrevall birth cohort – showed that 402 (26%) of 1,568 children aged 2.5 years or younger had a possible food allergy.
The results of double-blind, placebo-controlled food challenge tests showed that hen’s egg, peanut, cow’s milk, and wheat were the most common causes of food allergy. Estimating the overall prevalence of food allergy showed that about 2% of children had developed clinically relevant food allergy, accounting for “a tenth of those with suspected reactions,” said study investigator Dr. Thomas Keil of Charité.
“We are excited to see the results from other centers,” Dr. Keil added, noting that there may well be some differences from the Berlin findings, not only in prevalence but also in the allergens responsible. “EuroPrevall will hopefully provide good data on the prevalence patterns, risk factors, quality of life, and costs of food allergies in European children.”
Importantly, the EuroPrevall data have been collected via standardized methods, meaning that the natural course of food allergies among the participating European centers can be compared. This will help researchers examine possible risk factors for food allergy, Dr. Keil said.
Other recent data from the BAMSE (Barn Allergi Milieu Stockholm Epidemiologi) birth cohort have shown a protective role of breastfeeding on the development of asthma. Children who were breastfed for at least 4 months were significantly less likely to develop asthma by the age of 8 years than were those breastfed for fewer than 4 months (J. Allergy Clin. Immunol. 2010;125:1013-9).
The BAMSE birth cohort was established between 1994 and 1996, said Dr. Anna Bergström of the Institute of Environmental Medicine at the Karolinska Institutet in Stockholm. Starting out with more than 4,000 children, the cohort has been reevaluated multiple times – at 1, 2, 4, 8, and 12 years – with the 16-year follow-up begun in November 2010 and clinical examinations scheduled for January 2011.
“Several of the studies in the BAMSE cohort have suggested that it is important to consider disease-related modification of exposure when you study allergic disease in children,” Dr. Bergström observed.
For instance, recent findings of one unpublished study showed that the consumption of certain fruits and vegetables may temper the chances of developing allergic disease. “Consumption of total fruit, apples and pears, carrots, and legumes was inversely associated with allergic disease,” Dr. Bergström explained. However, after excluding children with food-related allergic symptoms, the associations mostly disappeared, suggesting that the avoidance of certain foods by affected children had influenced the associations.
Recent findings from the MAAS (Manchester Asthma and Allergy Study) cohort have shown that asthma and atopic disease are not single but most likely multiple diseases. MAAS started in 1995 and was designed to identify risk factors for the development of asthma and allergies in early life.
“In the 19th century, in textbooks of pediatrics, we had a disease that was called fever,” said Dr. Adnan Custovic, professor of allergy and head of the respiratory research group at University Hospital of South Manchester (England), which runs the MAAS.
“We have learned better; nobody would call a disease ‘fever’ nowadays,” Dr. Custovic said. “I certainly hope than in 10 years’ time that asthma will be confined to history just as much as fever has been confined to the history of diseases.”