“Direct infant UV light exposure is associated with eczema and immune development”.
Kristina Rueter, Anderson P. Jones, Aris Siafarikas, Ee-Mun Lim, Natasha Bear, Paul S. Noakes, Susan L. Prescott and Debra J. Palmer.
Article in press 2018 American Academy of Allergy, Asthma & Immunology https://doi.org/10.1016/j.jaci.2018.08.037
These graphical in JACI abstracts look a bit strange like “science for dummies”. It lets me wonder if there isn’t a major discrepancy of title and abstract?
Objective: We sought to determine the effects of early postnatal vitamin D supplementation on infant eczema and immune development.
Methods: By using a double-blind randomized controlled trial, newborn infants were randomized to receive vitamin D supplementation (400 IU/d) or a placebo until 6 months of age. Some infants also wore personal UV dosimeters to measure direct UV light (290-380 nm) 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.
Results: At 3 (P < .01) and 6 (P = .02) months of age, vitamin D levels were greater for the vitamin D–supplemented group than the placebo group, but there was no difference in eczema incidence between groups. Infants with eczema were found to have had less UV light exposure (median, 555 Joules per square meter [J/m2; interquartile range, 322-1210 J/m2]) compared with those without eczema (median, 998 J/m2 [interquartile range, 676-1577 J/m2]; P = .02). UV light exposure was also inversely correlated with IL-2, GM-CSF, and eotaxin production to Toll-like receptor ligands.
Conclusion: This study is the first to demonstrate an association between greater direct UV light exposures in early infancy with lower incidence of eczema and proinflammatory immune markers by 6 months of age. Our findings indicate that UV light exposure appears more beneficial than vitamin D supplementation as an allergy prevention strategy in early life.
IMHO this is a RCT of vitamin D supplementation of newborns and not a study of UV light exposure. Maybe the authors needed a selling point for a poorly designed study?
The (only) allergy outcome is shown in table. 6 of 90 in the placebo group and 9 of 90 in the vitamin group develop eczema. This translates into an OR of 1.6 (0.5-4.6, P = 0.4214). I read this as a non significant association of exposure and outcome which is quite understandable given
1. the low power of the study. My result of a post hoc power calculation is 12%.
2. the ignorance of the main eczema risk factor ( filaggrin mutation!). Allocation by a “history of maternal allergic disease” does not allocate filaggrin mutations equally between groups.
3. the ignorance of maternal vitamin D levels. Restricting to maternal levels >50 nmol/L introduced as a bias towards supplemented fetuses.
4. the ignorance of vitamin D fed by formula. So clearly this is only a done-finding study and not a RCT of vitamin D supplementation as also the controls are (heavily) exposed.
5. the ignorance of the most relevant outcome in this age group which is sensitization against food allergens.
Also the “vitamin D hypothesis” did not emerge to explain associations found between regions of higher latitudes and increased risk of development of allergic diseases in children. The references 2-5 are misleading. It emerged by theoretical considerations of the immune effects of artificial vitamin D supplementation.