Prevention of food allergy and atopic disease

Knowledge and practice of physicians and nutritionists regarding the prevention of food allergy

BACKGROUND & AIMS

To evaluate the knowledge and practice of pediatricians, pediatric gastroenterologists, allergists and nutritionists regarding the primary prevention of food allergy.

METHODS

A descriptive, cross-sectional study that enrolled pediatricians (n = 80), pediatric gastroenterologists (n = 120), allergists (n = 100) and nutritionists (n = 220). A self-administered questionnaire concerning the current recommendations was used.

RESULTS

Despite the lack of current recommendations, 17.1% (n = 89) of all professionals, mainly nutritionists, recommended a maternal exclusion diet during pregnancy. More professionals in the sample group, 40.8% (n = 212), recommended a maternal exclusion diet during breastfeeding, and the rates of recommendation were higher in nutritionists and pediatricians compared to allergists and pediatric gastroenterologists (p < 0.001). Regarding the recommended timing of the introduction of complementary feeding, 41.9% (n = 218) of the professionals recommended modifying the age of introduction to prevent the development of food allergy. The majority of the professionals believed that prebiotics (61.2%; n = 318) and probiotics (44.4%; 231) prevent the development of food allergy. The recommended age of introduction for the main allergenic foods was 12 months.

CONCLUSIONS

This study revealed that there are gaps in the knowledge of professionals about the primary prevention of food allergy.

Adherence to allergy prevention recommendations in children with a family history of asthma

Allergen avoidance has been a major component of most programs for primary prevention of asthma and allergic diseases in childhood. As a part of the Childhood Asthma Prevention Study, families were provided with written and oral information on measures considered to be helpful in the primary prevention of allergic disease in high-risk infants. Dietary measures included advice to breastfeed for 6 months or longer, to delay the introduction of solid foods until after the infant turned 6 months of age, and to delay giving allergenic foods (egg and peanut butter) until after 12 months of age. In the active group of the randomized controlled trial aimed at reducing house dust mite (HDM) allergen levels, parents were advised to use an HDM-impermeable study mattress cover and an acaricide, to avoid sheep skins, and not to use a pillow before 12 months of age. Families received regular visits from the research nurses at 1, 3, 6, 9 and 12 months and phone calls every 6 wk. Only 43.4% of mothers were breastfeeding by 6 months and less than 20% by 12 months. The introduction of solid foods before 6 months was common, 26% by 3 months and 96% by 6 months. Adherence to infant-feeding recommendations was significantly greater in women over 30 yr of age, women who did not smoke during pregnancy, and women who had a tertiary education. Adherence to HDM reduction measures was greater than to those for infant feeding. The presence of symptoms in the form of an itchy rash by 4 wk did not significantly increase adherence. Complete adherence to infant-feeding recommendations in this intervention study of high-risk infants was low despite the provision of written information and reinforcement at home visits. In considering allergy prevention advice offered during clinical care, the likelihood of adherence is a factor which needs to be evaluated in assessing any potential benefits of allergy prevention regimens.

Maternal-fetal interaction: preconception immunization in mice prevents neonatal sensitization induced by allergen exposure during pregnancy and breastfeeding

Allergen exclusion measures during pregnancy and lactation have been given consideration in studies of primary allergy prevention but complete avoidance of mother/neonatal allergen exposure has proven to be a difficult procedure. To evaluate a strategy to prevent allergen sensitization in early life in mice, we first established a neonatal model with ovalbumin sensitization through maternal allergen exposure during pregnancy or breastfeeding. The modulatory potential of preconception immunization was investigated on the neonatal development of subsequent allergic responses to maternal allergen exposure. Herein, we demonstrate that immunized mothers exposed to antigen during pregnancy or breastfeeding underwent intense vertical transmission of antibodies, including immunoglobulin G (IgG) in complex with ovalbumin and IgG1 antibody with anaphylactic function. It was further shown that maternal immunization efficiently decreased the passage of free antigens through breastfeeding and inhibited the enhanced IgE antibody response after postnatal antigen exposure. In addition, antenatal immunization decreased the antigen-specific proliferative response of immunized neonates, in parallel with profound downmodulatory effects on both the activation and differentiation of T and B cells after a non-specific stimulus and cytokine production. These findings showed that early life sensitization, subsequent to maternal allergen exposure during both the prenatal and postnatal periods, could be avoided by preventive vaccination of the mother.

Exposure of the fetus and infant to hens' egg ovalbumin via the placenta and breast milk in relation to maternal intake of dietary egg

BACKGROUND

Maternally derived allergens may be transferred to the developing infant during pregnancy and lactation. However, it is not known how manipulation of environmental allergen levels might impact on this early-life exposure.

OBJECTIVE

To measure dietary egg allergen (ovalbumin (OVA)) in gestation-associated environments, in relation to maternal dietary egg intake.

METHOD

OVA was measured by allergen-specific ELISA in maternal blood collected throughout pregnancy, infant blood at birth (umbilical cord) and in breast milk at 3 months post-partum. Samples derived from pregnant women undergoing diagnostic amniocentesis at 16-18 weeks gestation who were not subject to any dietary intervention, and from pregnant women, with personal or partner atopy, randomized to complete dietary egg exclusion or an unmodified healthy diet before 20 weeks gestation as a primary allergy prevention strategy. Maternal dietary egg intake was monitored closely throughout the study period by diary record and serial measurement of OVA-specific immunoglobulin G concentration.

RESULTS

Circulating OVA was detected throughout pregnancy in 20% of women and correlated with both presence (P<0.001) and concentration (r=0.754, P<0.001) of infant OVA at birth (umbilical cord). At 3 months post-partum OVA was detected in breast milk samples of 35% women, in higher concentrations than measured in blood. Blood and breast milk OVA were not related to maternal dietary intake or atopic pre-disposition.

CONCLUSIONS

Rigorous dietary egg exclusion does not eliminate trans-placental and breast milk egg allergen passage. This early-life exposure could modulate developing immune responses.

What is the role of the prevention of allergy in the first period of life?

The widespread increase in the prevalence of allergic disease, which has occurred over the last 20 y, has created general concern in Europe and in the rest of the world. The reason for this increase is still partially unknown. In this period, despite a greater understanding of the pathogenesis and risk factors of allergies plus the greater efficacy of drugs to control the symptoms, the cost of intervention and the socio-economic impact are still very high. For these reasons, prevention in the first period of life represents a goal for both developed and developing countries in order to reduce this upward trend.

Peanut allergy: an overview

Peanut allergy accounts for the majority of severe food-related allergic reactions. It tends to present early in life, and affected individuals generally do not outgrow it. In highly sensitized people, trace quantities can induce an allergic reaction. In this review, we will discuss the prevalence, clinical characteristics, diagnosis, natural history and management of peanut allergy.

Maternal compliance with nutritional recommendations in an allergy preventive programme

AIMS

To assess maternal compliance with nutritional recommendations in an allergy preventive programme, and identify factors influencing compliance behaviour.

METHODS

Randomised double-blind intervention study on the effect of infant formulas with reduced allergenicity in healthy, term newborns at risk of atopy. Maternal compliance with dietary recommendations concerning milk and solid food feeding was categorised.

RESULTS

A total of 2252 newborns were randomised to one of four study formulas. The drop out rate during the first year of life was 13.5% (n = 304). The rates of high, medium, and low compliance to milk feeding during weeks 1-16 were 83.4%, 4.0%, and 7.5%; the corresponding rates to solid food feeding during weeks 1-24 were 60.0%, 12.1%, and 22.9%. In 5.1% of subjects no nutritional information was available. Low compliance was more frequent among non-German parents, parents with a low level of education, young mothers, smoking mothers, and those who weaned their infant before the age of 2 months.

CONCLUSIONS

Evaluation of allergy preventive programmes should take into account non-compliance for assessing the preventive effectiveness on study outcome.

Early life exposure to dietary and inhalant allergens

Increasing evidence points to early life, including fetal life, as being a critical time period during which the infant's allergic fate may be determined. However, initial antigen priming in utero necessitates fetal exposure to maternally derived allergen. This article reviews our current knowledge regarding materno-fetal allergen transfer in vivo and reflects on mechanisms by which this exposure might exert immunomodulatory influences on the developing immune system.

Breastfeeding in countries of the European Union and EFTA: current and proposed recommendations, rationale, prevalence, duration and trends

Recommendations suggest exclusive breast feeding for at least the first 4 to 6 months after birth. Paradoxically, an overwhelming proportion of breast feeding (BF) data in Europe refers to all BF, i.e. not only exclusive but also partial BF (including formula, juices, water, sweetened water etc). This makes it difficult to estimate to what extent the recommendations are met. There is currently strong evidence for recommending exclusive breast feeding for at least 6 months. Exclusive BF has progressively gained scientific support. Prevention of infections, allergies and chronic diseases and a favourable cognitive development are highlighted in the recent scientific literature. Further long-term studies on the effects of BF on prevention of chronic disease in the adult are needed. Great differences exist in BF prevalence and duration both within and between European countries. Trends point towards higher prevalence and duration, with some exceptions. Young mothers breast feed less than older mothers; single and/or less educated mothers breast feed less than married mothers with more education. However, inefficient and unreliable monitoring systems prevail, and the data are scarce, not only on exclusive BF but also on demographic, socio-economic, psychosocial and medical determinants of BF patterns. National BF coordinators have not been appointed in many countries, and only every second country has promotion of BF incorporated into their national plan of action for nutrition.

CONCLUSIONS

Efficient surveillance systems, comparable across Europe and using common definitions and methodology, need to be developed. These should include determinants of breast feeding. A European consensus conference should urgently be organised, in which strategies for successful promotion of exclusive BF should be particularly considered. There is now strong evidence for a recommendation to breast feed exclusively for about 6 months, which is more than the duration recommended previously.

Peanut and tree nut allergy

Among foods causing allergic reactions in children, peanut (a legume) and tree nuts (ie, walnut, hazel nut, Brazil nut, pecan) have attracted considerable attention for several reasons. Allergies to these foods are common, frequently have an onset in the first few years of life, generally persist, and account for severe and potentially fatal allergic reactions. Furthermore, the ubiquity of these foods in the diet makes avoidance difficult and accidental ingestions, with reactions, common. This review discusses recent and emerging information on the prevalence, clinical characteristics, natural history, genetic basis, and current treatment of these allergies. In addition, recent advances in the molecular and immunologic characteristics of these allergens, and novel therapeutic options under investigation in animal models, are reviewed.

Effect of allergist intervention on patient-centered and societal outcomes: allergists as leaders, innovators, and educators

Atopic disorders, which afflict millions of Americans and hundreds of millions worldwide, are at epidemic levels with concomitant increases in morbidity and mortality. Environmental and lifestyle changes over the past three to five decades are proposed causes for this pandemic and as such present major burdens to reverse. The scope of allergy practice bridges directly on this challenge. Allergy as a specialty is a major leader in developing effective strategies to confront this epidemic. Allergists have made major contributions to the understanding of the risk factors, immunology, pathophysiology, immunomodulation, and prevention of atopic and immunologic disorders. Allergist epidemiologists and clinicians have helped develop and implement national and international guidelines in the recognition, management, and prevention of asthma and rhinitis. Allergist clinical researchers are active in (1) outcomes research that demonstrates convincingly the value of allergy as a specialty in asthma, allergic rhinitis, anaphylaxis, drug and food allergy, and other atopic disorders, (2) National Institutes of Health clinical trials that will form the basis for the future treatment of asthma and allergic disease, and (3) pharmaceutical trials that evaluate new, effective, and safe medication to treat atopic disease. Allergist educators, comprising academic and practicing allergists, supported by allied health professionals, national associations, and affiliated lay organizations, provide comprehensive education to fellows, residents, colleague physicians, media, the public, and patients. Documentation of the value of allergists in improving patient-centered and societal outcomes in their core domain, allergy, is the appropriate final topic contribution in the important series "New millennium: The conquest of allergy."

American Academy of Pediatrics. Committee on Nutrition. Hypoallergenic infant formulas

The American Academy of Pediatrics is committed to breastfeeding as the ideal source of nutrition for infants. For those infants who are formula-fed, either as a supplement to breastfeeding or exclusively during their infancy, it is common practice for pediatricians to change the formula when symptoms of intolerance occur. Decisions about when the formula should be changed and which formula should be used vary significantly, however, among pediatric practitioners. This statement clarifies some of these issues as they relate to protein hypersensitivity (protein allergy), one of the causes of adverse reactions to feeding during infancy.