As a secosteroid, vitamin D has bone health benefits, but more recently, scientists have discovered diverse functions of the vitamin.
Based on this, researchers from specialty healthcare organisation Sidra Medicine conducted a review of vitamin D functions in the area of skin physiology, focusing on its effects on certain inflammatory conditions, namely atopic dermatitis psoriasis.
They subsequently found that vitamin D is "integrally connected to the skin for its synthesis, metabolism, and activity".
In addition, vitamin D has been shown to regulate numerous physiological processes in the skin, such as differentiation, cellular proliferation, immune functions, barrier maintenance and apoptosis.
Several of the clinical or observational studies reviewed pointed to vitamin D's positive pleiotropic effect in treating inflammatory skin disorders, particularly psoriasis and atopic dermatitis.
D-day for dermatitis
Atopic dermatitis is a chronic or relapsing skin disorder triggered by interactions involving environmental, genetic and immunological factors, and is characterised by chronic inflammation, immunological abnormalities, and epithelial barrier disruption.
The researchers wrote: "In large population-based studies, it was observed that there is an increased likelihood of developing atopic dermatitis in individuals with either deficient or insufficient vitamin D levels" adding that "serum vitamin D level is lower in children and adults with atopic dermatitis compared to controls".
They also stated that the lower an atopic dermatitis patient’s vitamin D levels were, the more severe the condition.
Vitamin D supplementation was found to inhibit allergic response in atopic dermatitis patients by suppressing the immune system's production of the antibodies Immunoglobulin E (IgE).
Furthermore, vitamin D supplementation was shown to ameliorate lesions caused by atopic dermatitis by "restoring epidermal barrier defects and correcting the deregulated innate immune response".
The sack of psoriasis
Psoriais is a multifactorial chronic skin disease, in which immune dysregulation causes the innate and adaptive immune system to interact by way of a 'crosstalk'.
Several studies have noted psoriasis sufferers to be vitamin D-deficient, but there are conflicting reports showing no significant difference in serum vitamin D levels between those who suffer from psoriasis and those who do not.
However, numerous clinical studies have shown vitamin D to effectively treat psoriasis symptoms, especially when combined with corticosteroids, as the effects of both treatments are complementary.
Vitamin D has been found to suppress inflammatory cytokines (which are present in "abnormally high levels" in psoriatic skin), and reportedly corrects the abnormal epidermal function central to psoriasis.
Further exploration due
The researchers wrote that vitamin D's "role in the proper functioning of several tissues / organs, including the skin, has been receiving growing interest", adding that it is "intricately involved in many skin pathologies, and it positively influences the outcome of certain inflammatory dermopathologies".
They also said therapeutic interventions involving both systemic and topical applications of vitamin D have proven to alleviate psoriasis and atopic dermatitis.
In conclusion, they wrote: "Future studies are needed to mechanistically and intensely explore the specific pathways affected by vitamin D using the latest advanced technologies, and to assess the safety and efficacy of vitamin D-based treatment regimens in various inflammatory skin diseases."
Source: Skin Pharmacology and Physiology
"Vitamin D and the Pathophysiology of Inflammatory Skin Diseases"
Authors: Meenakshi Umar, et al.