Milner JD, Stein DM, McCarter R, Moon RY. Pediatrics. 2004;114:27–32
Purpose of the Study.
Dietary vitamins have immunomodulating effects in vitro, and individual vitamins have been shown to skew T cells toward either T-helper 1 or T-helper 2 phenotypic classes, suggesting that they may participate in inflammatory or allergic disease. The objective of the study was to determine if early vitamin supplementation during infancy affects the risk for asthma and allergic disease during early childhood.
Cohort data were analyzed from the National Center for Health Statistics 1988 National Maternal-Infant Health Survey, which followed pregnant women and their newborns, and the 1991 longitudinal follow-up of the same patients, which measured health and disease outcomes. There were >8000 patients in this study.
Patients were stratified by race and breastfeeding status. Factors that are known to be associated with alteration of risk for asthma or food allergies were identified by using univariate logistic regression. Those factors were then analyzed in multivariate logistic-regression models. Early vitamin supplementation was defined as vitamin use within the first 6 months.
The overall incidence of asthma was 10.5% and of food allergy was 4.9%. In univariate analysis, being male gender, having a smoker in the household, being in child care, being premature (<37 weeks’ gestation), being black, having no history of breastfeeding, and having lower income and lower education were associated with higher risk for asthma. Being in child care, having higher levels of education and income, and having a history of breastfeeding were associated with a higher risk for food allergies. In multivariate logistic analyses, a history of vitamin use within the first 6 months of life was associated with a higher risk for asthma in black infants (odds ratio [OR]: 1.27; 95% confidence interval [CI]: 1.04, 1.56). Early vitamin use was also associated with a higher risk for food allergies in the exclusively formula-fed population (OR: 1.63; 95% CI: 1.21, 2.20). Vitamin use at 3 years of age was associated with increased risk for food allergies but not asthma in both breastfed (OR: 1.62; 95% CI: 1.19, 2.21) and exclusively formula-fed (OR: 1.39; 95% CI: 1.03, 1.88) infants.
The conclusions of the authors were that early vitamin introduction is related to increased likelihood for asthma in black children and food allergies in exclusively formula-fed children.
Although there are some laboratory data to support the potential for some vitamins to cause naive T cells to differentiate to T-helper 2 phenotypes (allergy promoting), at this time the findings of this study are associational and not causal. There are numerous confounding factors that may have resulted in the observed associations. The authors proposed that there may have been cultural biases in diagnosis. It is also unusual that this association only held for vitamin use at 3 and 6 months of age but not at 3 years of age. It was noted that formula-fed infants who received (but did not need) multivitamins were at higher risk of food allergy than breastfed infants who received multivitamins. The authors could not evaluate the possibility that formula-fed infants were given multivitamins, because they had illnesses (such as atopic dermatitis or food allergy) that may have led to such interventions. The authors also indicated that it is possible that persons inclined to use multivitamins are also persons who are more likely to report their child’s health problems or seek more medical diagnoses for their child’s symptoms. Last, these data were collected ∼15 years ago, and since then the rates of asthma and food allergy have apparently increased significantly. It is not clear that the results would be similar today. The numerous potential confounding influences in this study require that the results be confirmed in other studies before any specific recommendations can be made.