Exposure to folic acid in utero may affect development of food allergies in children

Higher levels of unmetabolized folic acid (UMFA) at birth may be associated with the development of food allergy in children, according to results from a study presented at the 2018 American Academy of Allergy, Asthma & Immunology and World Allergy Organization Joint Congress held March 2-5, 2018, in Orlando, FL.

Researchers conducted this nested, case-control study using data from the Boston Birth Cohort, which included 1,394 children. In a subset of patients, total folate was measured with chemiluminescent assay, and 5-methyltetrahydrofolate (5-MTHF)/UMFA was measured via liquid chromatography-tandem mass spectrometry at birth (n=502) and in early life (n=362).

In addition, researchers assessed diet, clinical history, and specific-IgE (sIgE) to common food allergens. Children were classified as having a food allergy or not.

In all, 36% of subjects had food sensitization (sIgE ≥ 0.35 ku/L) and 5.6% were food allergic. In children who developed a food allergy, mean total folate levels at birth were lower compared to those who did not have an allergy (30.2 nmol/L vs 35.3 nmol/L, respectively; P=0.02), and mean levels of UMFA were higher (1.7 nmol/L vs 1.3 nmol/L; P=0.001).

Researchers found no association between the development of food allergies and early-life levels of total folate, 5-MTHF, or UMFA.

“Interestingly, while the mean total folate levels at birth were lower among the children that developed a food allergy, mean levels of the synthetic folic acid derivative, UMFA, were higher,” said author Emily C. McGowan, MD, assistant professor of medicine, Allergy and Clinical Immunology, University of Virginia Health System, Charlottesville, VA. Vitamin B9 (folate) is available in both natural and synthetic forms. Folic acid is the synthetic form and is often recommended during pregnancy to prevent neural tube defects. When taken in higher quantities, not all the folic acid is metabolized and is left circulating in the blood.

Increased levels of UMFA may be due to increased exposure to synthetic folic acid in utero or to underlying genetic differences, noted Dr. McGowan and colleagues.

“More research is needed to conclude whether mothers should consider consuming different sources of folate like leafy green vegetables, citrus fruits, beans, or lentils instead of synthetic forms of folate,” said author Corinne Keet, MD, MS, PhD, associate professor of pediatrics, Johns Hopkins University School of Medicine.