July 31, 2006 — The American College of Asthma, Allergy, & Immunology developed a consensus document for introducing solid foods into an infant's diet to avoid development of food allergies, and they published the new guidelines in the July issue of the Annals of Allergy, Asthma, & Immunology.

"Whereas parents and pediatricians can be in no doubt regarding the avoidance of cow's milk and dairy products as complementary foods for the primary prevention of allergic disease in at-risk infants, the same degree of confidence cannot be shared regarding the introduction of the child to a solid diet, for which no evidence- or consensus-based guidance is available," write Alessandro Fiocchi, MD, from the University of Milan Medical School in Italy, and colleagues from the Adverse Reactions to Foods Committee of the American College of Allergy, Asthma, and Immunology. "To compound the problem, there is no standard schedule for weaning infants who are healthy or at risk for allergy."

The objective of this consensus document was to make recommendations based on a critical review of the evidence for the timing of the introduction of solid foods and its possible role in the development of food allergy. Based on their clinical experience and research expertise, the authors retrieved 52 studies from MEDLINE searches that satisfied the following conditions: English language, journal impact factor above 1 or scientific society, expert, or institutional publication, and appraisable using the World Health Organization (WHO) categories of evidence.

A review of these studies suggested that early introduction of solid foods can increase the risk for food allergy, that avoidance of solids can prevent the development of specific food allergies, that some foods are more allergenic than others, and that some food allergies are more persistent than others.

The consensus statement recommends that pediatricians and allergists should cautiously individualize the introduction of solids into the infants' diet. For infants at high risk for allergy, the optimal age for the introduction of selected supplemental foods should be 6 months; 12 months for dairy products; 24 months for hen's egg, and at least 36 months for peanut, tree nuts, fish, and seafood.

"For all infants, complementary feeding can be introduced from the sixth month, and egg, peanut, tree nuts, fish, and seafood introduction require caution," the authors write. "Foods should be introduced one at a time in small amounts. Mixed foods containing various food allergens should not be given unless tolerance to every ingredient has been assessed."

Specific recommendations are as follows:

1. During the first 6 months of life, exclusive breast-feeding is recommended, with exclusion of cow's milk formulas and any supplemental foods. Exclusive breast-feeding protects against the onset of allergic symptoms extending far beyond the period of breast-feeding.
2. Complementary feeding of supplemental foods can be introduced starting at the sixth month of life. Introducing supplemental foods during the first 4 months of life has been associated with a higher risk for allergic diseases up to the age of 10 years, which confirms current WHO recommendations.
3. Exposure avoidance is an effective means of preventing cow's milk allergy. By extrapolation, delayed exposure to solid foods should prove to be similarly useful in preventing food allergies.
4. In the developed world, the main foods posing an allergy risk are bovine milk, egg, peanut, tree nuts, fish, and seafood. If introduced early, other foods can become clinically significant allergens. Therefore, it seems reasonable that foods should be introduced individually and gradually.
5. Mixed foods containing a variety of food allergens should not be given unless tolerance to every ingredient has been determined.
6. For processed foods, such as beef and kiwifruit, that are less allergenic when cooked, it is preferred to serve these foods cooked and homogenized.

The consensus statement points out that introducing solid foods is not an ideal research end point because its full benefit depends on the duration of breast-feeding.

"Devising a timetable leading to the definition and minimization of clinical risk in a defined population of likely candidates remains among the achievable goals of food allergy prevention," the authors conclude. "Faced with a parent asking 'which food' and 'when,' the pediatrician has to integrate a reasonable schedule for the introduction of solid foods based on biochemical, immunologic, and epidemiologic data. Choosing the food to be introduced depends on its 'allergenicity index,' which depends on several factors: (1) sensitization risk (how many children become sensitized to that food when exposed), (2) allergy risk (how many children sensitized to that food develop clinically relevant symptoms), (3) allergy persistence risk (the half-life of a diagnosis of allergy), and (4) personal risk (familial recurrence of allergic diseases)."

The authors have disclosed no relevant financial relationships. This feature is supported by an unrestricted educational grant from AstraZeneca LP.

Ann Allergy Asthma Immunol. 2006;97:10-21.