Direct Infant UV Light Exposure Is Associated With Eczema and Immune Development

Abstract

To determine the effects of early postnatal vitamin D supplementation on infant eczema and immune development.This study included 197 healthy, term, singleton infants with family history of atopy. Ninety-seven participants were randomly assigned to the intervention vitamin D group, and 98 were randomly assigned to the placebo group. Ninety-two percent of infants attended their appointment at 3 months of age, and 89% of infants attended their appointment at 6 months of age.This study was a double-blind randomized controlled trial of infants born in Australia between October 2012 and January 2017. Newborn infants were randomly assigned to receive vitamin D supplementation (400 IU/day) or a placebo until 6 months of age. Some infants also wore personal UV dosimeters to measure direct UV light exposure. Infant vitamin D levels were measured at 3 and 6 months of age. Eczema, wheeze, and immune function outcomes were assessed at 6 months of age. Eczema was defined by clinical features and graded on the basis of the Scoring Atopic Dermatitis score.At both 3 and 6 months of age, vitamin D levels were greater for the vitamin D group compared with the placebo group; however, there was no difference in eczema incidence between groups. The secondary outcome investigating direct UV light exposure found infants with eczema to have had less UV light exposure compared with those without eczema. Additionally, UV light exposure was also inversely correlated with interleukin-2, granulocyte-macrophage colony-stimulating factor, and eotaxin production to Toll-like receptor ligands.Researchers in this study found that UV light exposure in early infancy was associated with lower incidence of eczema and proinflammatory immune markers by 6 months of age. These findings suggest that UV light exposure may be more beneficial than vitamin D supplementation as an allergy prevention strategy in early life.Although the initial intent of this study was focused on vitamin D, the more remarkable finding related to the demonstrated association between greater direct UV light exposure in early infancy with lower incidence of eczema and proinflammatory immune markers. The lack of effect of vitamin D supplementation is consistent with previous studies in which researchers have reviewed vitamin D supplementation during pregnancy and infancy. Future studies would be ideal, powered for effect of direct UV exposure on the incidence of eczema and involving mechanistic studies. Additionally, future studies are required to determine how much sunlight exposure in infancy is both safe and effective.