Evidence suggests maternal supplementation with 1,000 IU (international units) per day of cholecalciferol (vitamin D) from 14 weeks gestation to delivery reduces the risk of eczema in babies breastfed for more than one month, say the authors of a recent study.
Writing in the British Journal of Dermatology, they assert that the developmental influence of vitamin D was observed for up to one year after delivery, which supports “cholecalciferol supplementation as a preventive strategy to reduce the burden of atopic eczema during infancy”.
Lead researcher, Professor Keith Godfrey comments: “We know that Vitamin D can affect the immune system and the proteins that make up our skin. We were interested to know if Vitamin D supplements taken by pregnant women would have an impact on their child’s risk of atopic eczema.
“Our findings showed a positive effect, which was more evident in infants that breastfed. This may reflect supplementation during pregnancy increasing the amount of Vitamin D in breast milk.”
Genetic impact
Cases of atopic eczema have steadily increased in recent decades and now affect approximately 9.5% of children under four years of age and 16.5% aged one to six years.
Indications suggest a strong link between in utero genetic susceptibility and environmental exposure on the developing immune systems that may impact the skin barrier, which is important in the pathogenesis of eczema and other atopic diseases.
The researchers explain: “Vitamin D and its metabolites can impact this through involvement in the synthesis of proteins such as filaggrin, and through stratum corneum formation, keratinocyte formation and differentiation and production and the regulation of skin antimicrobial peptides.”
Inconsistent evidence
Clinical evidence linking the condition to maternal vitamin D status is compelling, but results are often inconsistent, the authors write.
Previous studies indicate an increased risk of atopic eczema with both low and high intake, while another observed reduced wheezing and eczema symptoms in children exposed to maternal consumption of 174 IU/d of vitamin D.
Even so, with deficiencies prevalent in many countries, supplementation with 400-600 IU/d cholecalciferol throughout pregnancy is widely recommended to bolster foetal development.
Protocol
In the current study, researchers examined the action of supplementation on decreased risk of atopic eczema, and whether there was any correlation on outcomes with breastfeeding or genetic variants associated with serum concentrations.
The double-blind randomised trial was designed as part of the UK Maternal Vitamin D Osteoporosis Study (MAVIDOS) to investigate the effect of maternal vitamin D intake at 12, 24 and 48 months. Participants were assigned to either the intervention group (351) or placebo (352).
Inclusion criteria included women over the age of 18 years who were pregnant with a single infant at a gestation age of less than 17 weeks and with baseline serum 25(OH)D between 25 and 100 normal levels (nmol/l).
Results
There was no association between maternal serum 25(OH)D in late pregnancy and infant atopic eczema, according to study data.
Mothers receiving supplementation showed a lower odds ratio (OR) at 12 months, but the effect weakened and was not statistically significant at ages 24 to 48 months.
“We speculate that during infancy there may be a role of breast milk vitamin D content,” the authors say.
Results suggest other postnatal influences may determine risk outcomes of atopic eczema beyond infancy, such as heterogeneity in the aetiology and pathogenesis of the condition in early childhood and different interactions with individual phenotypes.
“Alternatively, supplementation during the postnatal period may be needed for a sustained effect,” they add.
Source: British Journal of Dermatology
Published online: doi.org/10.1111/bjd.21721
‘Maternal antenatal vitamin D supplementation and offspring risk of atopic eczema in the first 4 years of life: evidence from a randomised controlled trial’
Sarah El-Heis et al.