Anaphylaxis caused by hidden soybean allergens in pillows.

in food sensitization rates were first observed at age 3 years, these differences between the 2 folate groups were not statistically significant until age 6 years. Because of the modest sample size, we were unable to determine whether the risk of food sensitization was also borne out as an increased risk in likely food allergy. The mechanisms underlying our observations are unclear. Although folate has a myriad of biologic effects, one current hypothesis posits that it may promoteDNAmethylation since it serves as a methyl donor, thereby suppressing the expression of key immune regulatory genes. Although these findings point to the potential for folate to act via an epigenetic mechanism in early childhood, folate hasmany roles in cellular function so that itmay act on the pathogenesis of allergic sensitization by other mechanisms. Other potential confounding factors may include breastfeeding, consumption of high-folate-containing (or folatefortified) foods. In this study, we found no significant difference between breast-feeding in both clusters (data not shown). Although we cannot ascertain exactly what role diet may have contributed to variability in our findings, in this study dietary folic acid intake would not be considered a true confounder as it is present in the causal pathway; since dietary intake is the major driver of plasma folate levels, our use of plasma folate levels already captures the dietary intake of folic acid. However, it is possible that plasma folate levels are simply a marker in general of a healthy diet and that some other component of a healthy diet—such as another micronutrient—could be the true driver of allergic sensitization risk rather than folate. The observational study design does not allow for the evaluation of this question, and so this limitation could not be controlled for in a natural history study such as Childhood Origins of Asthma. In summary, we found in a high-risk birth cohort that higher folate levels in early childhood were significantly associated with the increased incidence of both food and aeroallergen sensitization, suggesting that folate may confer the risk of allergy not only in utero but also in the first few years of life. These findings suggest that modification of folate intake in early childhood could reduce the risk of allergic sensitization and support the conduct of larger prospective studies to determine whether these findings are reproducible and whether folate affects the risk of allergic disease as well as the risk of allergic sensitization. Adesua Y. Okupa, MD Robert F. Lemanske, Jr, MD Daniel J. Jackson, MD Michael D. Evans, MS Robert A. Wood, MD Elizabeth C. Matsui, MD, MHS