Published online: October 23, 2018
Over the last few decades, allergies have increased in young children, suggesting the need to investigate changing diet and environmental factors over this time period. One example is reduced sunlight exposure, with increased sun protection practices and less time spent outdoors. Traditionally we relied on sunlight exposure to ensure that we had good vitamin D levels needed for healthy bone development, but in recent years the taking of vitamin D supplements to reduce the need for sun exposure has become more common. Interestingly, several studies have previously linked low vitamin D levels in early life with the development of childhood allergies.
A double-blinded randomized controlled trial from Rueter and colleagues, published in The Journal of Allergy and Clinical Immunology (JACI) studied 195 infants with a family history of allergies. Each infant in this trial was randomly assigned to one of two groups. One group (vitamin D) of 97 infants received vitamin D supplementation (400 IU/day) from birth to six months of age. The other group (placebo) of 98 infants received an identical product of coconut and palm kernel oil but containing no vitamin D supplementation, also from birth to six months of age. Both groups of infants were given this orally as one drop of liquid per day. Some infants (in both groups) wore personal ultraviolet (UV) light dosimeters to measure their individual direct sunlight exposure from birth to three months of age. Infant vitamin D levels were measured at three and six months of age. Eczema and immune development outcomes were assessed at six months of age.
Rueter and colleagues found that at three and six months of age, vitamin D levels were higher for the vitamin D supplemented group than the placebo group, but there was no difference in the number of infants with eczema between the groups. However, infants with eczema by six month of age were found to have had less UV light exposure in their first three months of life compared to those infants without eczema. Lower UV light exposure was also associated with more inflammatory immune development in the infants by six months of age.
In summary, this study is the first to demonstrate an association between higher direct individual sunlight exposures in early infancy with less eczema development by 6 months of age. These findings indicate that sunlight exposure appears to be more beneficial than vitamin D supplementation as an allergy prevention strategy in early life.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.
Direct infant UV light exposure is associated with eczema and immune development.