Increased food allergy and vitamin D: randomized, double-blind, placebo-controlled trial.

Background: To elucidate whether maternal vitamin D supplementation during lactation improves infantile eczema and other subsequent allergic disorders, a randomized, double-blind, placebo-controlled trial was performed.

Methods: Mothers (n = 164) of infants with facial eczema at 1 month check-up were randomly assigned to receive vitamin D3 supplements (n = 82; 800 IU/day) or placebo (n = 82) for 6 weeks from May 2009 to January 2011. The primary outcome was infantile eczema quantified on Scoring Atopic Dermatitis (SCORAD) index at 3 month check-up, and the secondary outcomes were atopic dermatitis, food allergy, and wheeze diagnosed by doctors up to 2 years of age.

Results: There was no significant difference in SCORAD at 3 month check-up between the two groups. Doctor-diagnosed food allergy was significantly more common up to age 2 years in the vitamin D group (10/39, 25.7%) than in the placebo group (3/40, 7.5%; risk ratio (RR), 3.42; 95% confidence interval [CI]: 1.02-11.77; P = 0.030). Moreover, at least one secondary outcome was also significantly more common in the vitamin D group (17/39, 43.6%) than in the placebo group (7/40, 17.5%; RR, 2.49; 95%CI: 1.16-5.34; P = 0.012).

Conclusions: Vitamin D supplementation may not decrease the severity of infantile eczema at 3 months of age, but may rather increase the risk of later food allergy up to 2 years of age. Because a large number of subjects was lost to follow up, further study is needed to confirm the findings.