Antenatal vitamin D suggested to prevent infant atopic eczema

Vitamin D supplementation should be considered for both pregnant mothers preventing atopic eczema in infants, an Australian dermatologist has suggested.

Associate Professor David Orchard of the Department of Dermatology, The Royal Children’s Hospital Melbourne, says that results from the first randomised controlled trial of antenatal vitamin D supplementation on the risk of infantile atopic eczema have shown positive results, possibly via increased breast milk cholecalciferol levels.

The UK study involved more than 1100 pregnant women who took either daily 1000 IU vitamin D supplementation from week 14 of pregnancy or placebo as part of a study to investigate effects on bone health.

The effects on infant eczema rates was investigated as a secondary outcome and showed that there was a significant reduction in atopic eczema in the intervention group at age 12 months compared with control.

The offspring of mothers who received vitamin D had a 45% lower risk of atopic eczema at age 12 months (OR 0·55, 95% CI 0·32–0·97, P = 0·04).

However there was no significant difference seen in atopic eczema rates seen between intervention and control groups at ages 24 months (OR 0·76,) or 48 months (OR 0·75, 95% CI 0·37–1·52).

The study investigators said this suggested that other postnatal influences might become important at older ages in affecting the risk of atopic eczema beyond infancy.

“Conceivably, supplementation during the postnatal period may be needed for a sustained effect,” they wrote, noting there was evidence supportive of postnatal vitamin D supplementation, being associated with reduced eczema severity.

Further analysis showed that the potentially protective effect of vitamin D against eczema was confined in infants breastfed for one month or more in whom the risk reduction was 52%, compared to those who had less than one month of breastfeeding (OR 0·80).

The study investigators noted that previous studies have shown that gestational vitamin D supplementation increases breast milk vitamin D content and in it was likely to have been higher in the study group, influenced by mobilisation from maternal fat and muscle tissue.

They said there were several mechanisms by which vitamin D could potentially protect against atopic eczema, including immunomodulatory effects on innate and adaptive responses. Vitamin D and its metabolites could also influence skin barrier function through involvement in the synthesis of proteins such as filaggrin, and through stratum corneum formation, keratinocyte formation and differentiation, and production and regulation of skin antimicrobial peptides.

Noting that many international and national guidelines recommend cholecalciferol 400–600 IU daily (10–15 μg) throughout pregnancy, they concluded that “the current findings inform understanding of the early-life influences on infantile eczema and support recommendations for routine vitamin D supplementation during pregnancy.”

In his accompanying commentary, Associate Professor Orchard observed that the study was not conducted in a high-risk atopic population and conclusions could not be drawn for those with a strong atopic family history, who would potentially benefit most from any protective effect of vitamin D on infant atopic eczema.

The question of whether it is more important to supplement the mother and/or infant with vitamin D also remains unanswered.

But with atopic dermatitis being an extremely common paediatric disease, the potential other health benefits of vitamin D and its lack of contraindication in pregnant women suggested it could have a role in antenatal prevention, he said.

“This study  … has suggested that vitamin D supplementation ought to be considered for both pregnant mother and newborn for those trying to minimise atopic eczema,” he concluded.

The findings are published in the British Journal of Dermatology.

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