“Our randomised, double-blind, placebo-controlled trial of children with winter-related AD found that oral vitamin D3 supplementation with 1000 IU daily for one month led to clinically and statistically significant improvements in AD,” wrote the scientists in the Journal of Allergy and Clinical Immunology. The lead researcher put the effect down to vitamin D's immune system-boosting potential.
AD is an inflammatory skin disorder that primarily affects children and often worsens in winter. For decades, this winter-worsening has been attributed to factors such as ambient humidity. Severe cases are treated with UV light in a controlled setting and the potential role of vitamin D has been largely ignored.
In 2006, the researchers hypothesised that at least part of the benefit of UV light exposure was due to improved vitamin D status and that oral vitamin D supplementation might reduce the severity of the condition. They found preliminary support for this theory in a small pilot study involving 11 children.
Larger scale study
This latest study tested the effect of vitamin D supplementation on winter-related AD in more than 100 children in Mongolia, a population known to have high levels of vitamin D deficiency during winter. The children, who had a mean age of nine, were randomly assigned either vitamin D in the form of oral cholecalciferol (1000 IU per day) or a placebo, as a daily supplement for one month.
In the vitamin D group a significant improvement in EASI (Eczema Area and Severity Index) score was noted (-6.5 versus -3.3 for the placebo group). IGA (Investigator’s Global Assessment) scores and secondary outcomes also showed that children on vitamin D fared better than those allocated a placebo. For example, parental assessment that the AD was “better” than at baseline started to diverge at two weeks and was statistically different by one month (64% among the vitamin D group and 43% among the placebo group).
“These findings build on our 2008 publication showing similar results in 11 Boston children,” wrote the researchers.
While the latitude of Ulaanbaatar may seem unusually high, the researchers pointed out that it is actually similar to that of Montreal and Paris and that many European and North American cities are at even higher latitudes and their populations include many vitamin D deficient individuals.
They said that oral vitamin D supplementation may safely improve signs and symptoms of AD without exposure to potentially harmful UV radiation.
Lead researcher Dr Carlos Camargo told NutraIngredients that, “vitamin D’s effects on innate immunity” was thought to be behind these results.
“The active form of vitamin D induces expression of antimicrobial peptides in the skin and thereby helps prevent skin infection and immunosuppress specific properties in the skin,” explained the researchers.
This study adds to a growing body of data suggesting that vitamin D deficiency may contribute to an extraordinary range of diseases, besides playing a major role in calcium metabolism and bone health.
Vitamin D supplementation for all?
Nevertheless, vitamin D supplementation or fortification policies are unlikely to be adopted by governments.
“Most governments discourage vitamin D testing on the grounds that it is too expensive and vitamin D supplementation unless a person has a clear deficiency, on the grounds of limited randomised controlled trial evidence,” said Dr Carmago.
He continued: “In 2011, the Institute of Medicine released their report on vitamin D and that’s the closest thing to US policy on the issue. They wrote that there was limited data on non-bone outcomes and they encouraged randomised controlled trials. We report a positive randomised controlled trial for a non-bone outcome.”
Journal of Allergy and Clinical Immunology
October 2014, DOI: http://dx.doi.org/10.1016/j.jaci.2014.08.002
“Randomized trial of vitamin D supplementation for winter-related atopic dermatitis in children”
Authors: Carlos A. Camargo, D. Ganmaa, Robert Sidbury, Kh. Erdenedelger, N. Radnaakhand, and B. Khandsuren