N Engl J Med. 2003 Mar 13;348(11):977-85.
Factors associated with the development of peanut allergy in childhood.
Lack G, Fox D, Northstone K, Golding J; Avon Longitudinal Study of Parents and Children Study Team.
Department of Paediatric Allergy and Immunology, St. Mary's Hospital at Imperial College, London, United Kingdom.
[ Free full text ]

BACKGROUND: The prevalence of peanut allergy appears to have increased in recent decades. Other than a family history of peanut allergy and the presence of atopy, there are no known risk factors. METHODS: We used data from the Avon Longitudinal Study of Parents and Children, a geographically defined cohort study of 13,971 preschool children, to identify those with a convincing history of peanut allergy and the subgroup that reacted to a double-blind peanut challenge. We first prospectively collected data on the whole cohort and then collected detailed information retrospectively by interview from the parents of children with peanut reactions and of children from two groups of controls (a random sample from the cohort and a group of children whose mothers had a history of eczema and who had had eczema themselves in the first six months of life). RESULTS: Forty-nine children had a history of peanut allergy; peanut allergy was confirmed by peanut challenge in 23 of 36 children tested. There was no evidence of prenatal sensitization from the maternal diet, and peanut-specific IgE was not detectable in the cord blood. Peanut allergy was independently associated with intake of soy milk or soy formula (odds ratio, 2.6; 95 percent confidence interval, 1.3 to 5.2), rash over joints and skin creases (odds ratio, 2.6; 95 percent confidence interval, 1.4 to 5.0), and oozing, crusted rash (odds ratio, 5.2; 95 percent confidence interval, 2.7 to 10.2). Analysis of interview data showed a significant independent relation of peanut allergy with the use of skin preparations containing peanut oil (odds ratio, 6.8; 95 percent confidence interval, 1.4 to 32.9). CONCLUSIONS: Sensitization to peanut protein may occur in children through the application of peanut oil to inflamed skin. The association with soy protein could arise from cross-sensitization through common epitopes. Confirmation of these risk factors in future studies could lead to new strategies to prevent sensitization in infants who are at risk for subsequent peanut allergy.

From the full text article:

Of the total cohort of children, 8.3 percent had consumed soy milk or soy formula in the first two years, as compared with 24.5 percent of those with peanut allergy and 34.8 percent of those with a positive peanut challenge (P<0.001 for both comparisons). Of the 10 children for whom data on the first consumption of soy milk or soy formula were available, 9 had consumed soy before reacting to peanuts.

[...]

All the significant factors listed in Table 1 were entered into a regression analysis. Early soy consumption, rash over the joints and skin creases (eczema), and oozing, crusted rash remained independent risk factors for peanut allergy and for a positive peanut-challenge test after adjustment for other factors (Table 2). It is likely that children with allergy to cow's milk or with eczema are at increased risk for food allergies, and soy consumption in infancy is increased in response to these atopic disorders. Indeed, a history of allergy to cow's milk (reported prospectively at six months) was significantly associated with peanut allergy (P=0.03). However, of the 289 children in the entire cohort reported to be allergic to cow's milk (2.7 percent), only 4 (0.1 percent) were allergic to peanuts. Milk allergy was not independently associated with peanut allergy (P=0.5), since the relation was completely explained by exposure to soy. Similarly, allergy to eggs did not confound the association between peanut allergy and soy consumption. Furthermore, the association with soy consumption was not altered when rash was included in the regression analysis.

[...]

Consumption of soy by the infants was independently associated with peanut allergy and could not be explained as a dietary response to other atopic conditions. It nevertheless remains possible that the association with soy consumption may have been confounded by other, unknown factors. Although immunologic coreactivity occurs among peanuts, soybeans, and other legumes,15 there is a low prevalence of clinical reactivity to soy in infants with peanut allergy.16,17 No subject in this study was reported to have had reactions to both peanuts and soy. Soy-protein fractions have been shown to be homologous to major peanut proteins,18,19 and exposure to a common soy T-cell epitope could cause cross-sensitization to peanuts, without necessarily resulting in clinical soy allergy.

Categories: 2003, Soy, Legumes, Dairy, Allergy, Nutrition and diet