Dr. Dena Herman: The study by Gupta et al, 2011, published in the July issue of Pediatrics, describes the results of a study on pediatric food allergy prevalence in the United States. Data were analyzed on a final sample of 38,480 children to assess the prevalence and severity of food allergies. The authors found that in contrast to other studies which have found a range of prevalence of childhood allergies between 2 to 8 percent, the prevalence of childhood allergies reported in this study was 8 percent, or a total of 5.9 million children.
Of those with allergies, 40 percent reported a history of severe reactions and 30 percent reported having multiple allergies. Consistent with other reports, this study found that the probability of severe food allergy increased progressively with age, peaking at more than twofold for a higher odds of severe reaction among children 14 to 17 years versus those 0 to 2 years. Black and Asian children had significantly higher odds of food allergies compared with white children but significantly lower odds of having the allergy diagnosed.
Dr. Dena Herman: The National Children's Study (NCS) will examine the effects of the environment -- as broadly defined to include factors such as air, water, diet, sound, family dynamics, community and cultural influences, and genetics -- on the growth, development, and health of children across the United States, following them from before birth until 21 years of age. The goal of the study is to improve the health and well-being of children and contribute to understanding the role various factors have on health and disease.
Dr. Dena Herman: It is understood today that early life events -- both exposures prior to pregnancy as well as those that occur during pregnancy -- can have critical effects on fetal development with lasting implications for subsequent health disease susceptibility. There is also growing interest in how modern environmental changes influence fetal immune development and contribute to the recent increase in allergy and other immune disorders. Because the NCS will examine environmental factors as they relate to genetics from the time before birth until children reach 21 years, results from the study may help researchers to better understand the development of allergies. Asthma is the most common cause of chronic childhood disease in the US and is one of the primary health outcomes being studied as part of the NCS.
Dr. Dena Herman: The NCS is unique not only because it is the largest long-term study on environmental influences on children's health and development ever to be conducted in the United States, but it is also unique because it begins studying participants before birth and includes children and families from different areas of the country, from varied backgrounds and different family types. The NCS will represent the nation's children and will provide information to help researchers better understand children's health throughout Los Angeles County and in more than 100 other counties across the nation. Information from the study will help doctors and researchers better understand asthma, diabetes, obesity and other childhood conditions.
Dr. Dena Herman: There are a number of theories for the increase in incidence and severity of food and other allergies in children.
Although both genetics and environmental exposures could explain some of the increase in prevalence, there is a growing understanding that the reasons for these increases lie in part with what is known today as fetal programming or the developmental origins of adult disease. This "theory," most commonly known as the "Barker Hypothesis," proposes that fetal exposure to an adverse uterine environment includes lifelong changes in various organ systems that in turn provide a basis for particular diseases later in life.
The fetal programming hypothesis may provide new insight into the origins of allergies including those related to food and airway disease such as asthma. One theory is that intrauterine events, such as the passage of antigens or immunologic signals across the placenta, can trigger allergies later in life by affecting immune and lung development. One study conducted in the Netherlands showed that the type of fats mothers consumed prenatally had an effect on the predisposition of children to develop allergic hypersensitivity reactions. They showed a decreased risk of eczema in the first seven months of life with increasing arachidonic acid levels. More research is necessary to confirm the results of this one study.
Dr. Dena Herman: Although an individual can be allergic to any food, eight foods account for 90 percent of all food-allergic reactions in the United States: milk, eggs, peanuts, tree nuts, wheat, soy, fish and shellfish. Children typically outgrow allergies to milk, eggs, wheat and soy. However, peanut, tree nut, fish and shellfish allergies are usually lifelong. Short-term risks of food allergies can be severe, as some food allergies lead to anaphylaxis, which can result in death if not properly treated. A recent study showed that food allergies may also be associated with an increased risk of asthma. The association was shown to be stronger among children with multiple or severe food allergies, especially in older children. In this study, children with food allergies developed asthma earlier and at a higher prevalence than children without food allergies. While this is a relatively new finding, this shows that food allergies can lead to more severe health consequences for young children.
Dr. Dena Herman: The results of the NCS will be available on an ongoing basis with the first results of the main study being available between 2 to 5 years after the first participants are recruited. Data from the NCS will first need to be reviewed and then aggregated at the national level before they can be released.
Dr. Dena Herman: Parents of children with food allergies need to be proactive in the management of their children's condition. First and foremost, it is important to avoid exposure to any and all foods that a child is allergic to. The Centers for Disease Control (CDC) and the Food Allergy and Anaphylaxis Network (FAAN) have developed documents for parents and children to understand how they can best manage these conditions. The websites for these two organizations are:
Here are several tips for daily management of children's food allergies:
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