Prenatal folate and other methyl donor intake are currently being evaluated as potential contributors to the development of childhood asthma. Existing studies have been variable, showing both positive and negative associations of dietary methyl donor intake with childhood asthma. This study seeks to look more comprehensively at the dietary intake of methyl donors during pregnancy and its association with the development of childhood asthma.
Subjects were 1052 mother-child pairs in Project Viva, an ongoing prospective cohort study. Maternal dietary and supplemental intake was assessed using validated food-frequency questionnaires administered in the first and second trimesters. The six nutrients assessed were folate, choline, betaine, and vitamins B2, B6, and B12, with and without supplementation. Because the distributions of the nutrients differed, z-scores were generated for each of the nutrients and used as the exposure of interest. The primary outcome was current physician-diagnosed asthma at age 7 years. We used multivariable logistic regression to adjust for age, BMI, asthma, education, and household income of the mother, as well as birth weight, sex, race/ethnicity, duration of breastfeeding, environmental tobacco smoke exposure, and eczema, of the child.
Of the 1052 children, 219 (20.8%) were diagnosed with asthma, 715 (68.0%) were Caucasian, 143 (13.6%) were African American, 38 (3.6%) were Hispanic, 34 (3.2%) were Asian and 122 (11.6%) were other race/ethnicity. In the univariate models, higher intake of folate, choline, B2, and betaine were associated with lower asthma prevalence. However, in the adjusted models for each nutrient, only dietary choline and vitamin B12 (without supplementation) in the 1st trimester were associated with lower asthma prevalence. Considering that these nutrients are in the same one-carbon metabolism pathway, we created a single model combining all six nutrients together along with the other co-variates of interest. In this combined model, B6 (OR 1.52, 95%CI=1.04, 2.21) and dietary choline (OR 0.72, 95% CI=0.56, 0.93) were significantly associated with childhood asthma.
Our results suggest that maternal intake of dietary methyl donors in the 1st trimester of pregnancy may modulate the risk for childhood asthma. The change in direction and strength of effect of dietary intake of B6 when adjusting for other dietary methyl donors suggests that these nutrients interact with one another in modulating the risk for childhood asthma.
Trivedi M et al. presented at the American Thoracic Society conference in San Diego on 20 May 2014