Infant food allergy linked to childhood asthma, study finds
Researchers have found a link between infant food allergy and asthma and reduced lung function in later childhood. They say their findings can help healthcare professionals to be more vigilant around monitoring the respiratory health of children with early food allergies.
The Murdoch Children’s Research Institute (MCRI) in Melbourne, Australia, led the research involving 5,276 children from the HealthNuts study, a world-first longitudinal study of how allergies in early life affect children’s health and well-being into adolescence.
Food allergies among children are a growing concern. Australia has one of the highest prevalences of childhood food allergy in the world, with the condition affecting more than 10% of infants. In the US, the Centers for Disease Control and Prevention (CDC) states that one in 13 children has a food allergy. Because the body’s immune system overreacts to food as if it were dangerous, some allergic reactions can be severe and even life-threatening.
In the current study, one-year-old participants underwent skin prick testing for four food allergens (egg, peanut, sesame, and either shrimp or cow’s milk) and an oral food challenge (OFC) for egg, peanut and sesame. An OFC involves being fed the allergen in small and increasing amounts over a few hours. If the child reacts to the food during an OFC, the challenge result is positive, meaning the child is allergic to that food. The same terminology is used for skin prick allergen tests. The tests were performed in a hospital setting. Parents were asked to complete a questionnaire about their child’s allergy history, demographic characteristics, and environmental exposures.
Then, at age six, the children had a follow-up health assessment that included skin prick testing for 10 foods (milk, egg, peanut, wheat, sesame, soy, shrimp, cashew, almond, and hazelnut) and eight aeroallergens (the fungi alternaria and cladasporium, dust mite, cat and dog hair, Bermuda grass, rye grass, and birch mix), OFC and lung function tests. Again, parents completed a questionnaire about the child’s allergy and respiratory history and demographics.
Lung function testing included forced expiratory volume (the amount of air a person can force out of their lungs over one second), forced vital capacity (the amount of air that can be forcibly exhaled after taking the deepest breath possible), and responsiveness to bronchodilators, the drugs used to open the constricted airways in asthmatics. These tests are considered reliable measures of lung function and can identify respiratory conditions such as asthma.
Of the 5,276 children in the study, 3,233 completed the health assessment at six years and were included in the analysis. The researchers found that 13.7% of children had been diagnosed with asthma by age six. Infants with a food allergy were almost four times more likely to develop asthma at six than children without an allergy. The impact was greatest in children whose food allergy persisted until six, as opposed to those who’d outgrown their allergy. And they found that children with a food allergy were more likely to have reduced lung function.
Based on their findings, the researchers concluded that a food allergy in infancy, whether outgrown or not, was linked to poorer respiratory health in children.
“This association is concerning given reduced lung growth in childhood is associated with health problems in adulthood, including respiratory and heart conditions,” said Rachel Peters, the study’s lead author.
The researchers have posited reasons for this link.
“Lung development is related to a child’s height and weight, and children with a food allergy can be shorter and lighter compared to their peers without an allergy,” said Peters. “This could explain the link between food allergy and lung function. There are also similar immune responses involved in the development of both food allergy and asthma.”
They say their findings could help healthcare professionals tailor patient care and encourage vigilance around monitoring the respiratory health of children with food allergies early in life.
The study was published in the journal The Lancet Child & Adolescent Health.