The role of vitamin D in melanogenesis with an emphasis on vitiligo.

Vitiligo is a common pigmentary disorder caused by the destruction of functional melanocytes. Vitamin D is an essential hormone synthesized in the skin and is responsible for skin pigmentation. Low levels of vitamin D have been observed in vitiligo patients and in patients with other autoimmune diseases. Therefore, the relationship between vitamin D and vitiligo needs to be investigated more thoroughly. We reviewed the literature to date regarding the role of vitamin D in skin pigmentation. Our review revealed that vitamin D deficiency has been identified in many conditions, including premature and dysmature birth, pigmented skin, obesity, advanced age, and malabsorption. Vitamin D increases melanogenesis and the tyrosinase content of cultured human melanocytes by its antiapoptotic effect. However, a few growth-inhibitory effects on melanocytes were also reported. Vitamin D regulates calcium and bone metabolism, controls cell proliferation and differentiation, and exerts immunoregulatory activities. Vitamin D exerts its effect via a nuclear hormone receptor for vitamin D. The topical application of vitamin D increased the number of L-3,4-dihydroxyphenylalanine-positive melanocytes. The topical application of vitamin D yields significant results when used in combination with phototherapy and ultraviolet exposure to treat vitiligo in humans. Vitamin D decreases the expression of various cytokines that cause vitiligo. In conclusion, application of vitamin D might help in preventing destruction of melanocytes thus causing vitiligo and other autoimmune disorders. The association between low vitamin D levels and the occurrence of vitiligo and other forms of autoimmunity is to be further evaluated.

Photoprotection and vitamin D status: a study on awareness, knowledge and attitude towards sun protection in general population from Kuwait, and its relation with vitamin D levels.

BACKGROUND: The primary cause of skin cancers is exposure to ultraviolet (UV) radiation. And, for decades sun protection has been promoted in various public health education campaigns. Recently, however, vitamin D deficiency has been related to increased risk of skin cancers. And, skin being the primary site for the synthesis of active form of vitamin D, excessive sun protection could lead to vitamin D-deficient states. But, the results have so far been conflicting. AIMS: To study the level of awareness, knowledge and attitude of representative groups from the general population from Kuwait towards sun protection. And, also study the correlation of the level of sun protective measures used and vitamin D levels in these groups. METHODS: The study constituted of two main parts. First part comprised a questionnaire-based survey of representative group of people aged 18 and above to assess their knowledge, awareness and attitude towards sun protection. The second part consisted of measuring serum vitamin D levels in 150 volunteers amongst the responders of the questionnaire, who had been regularly using sunscreens for at least 2 years and compare to the levels seen in 150 age and sex-matched responders of similar skin phototypes, who had never used sunscreens. RESULTS: Out of the total of 1044 responders, 80% of them had adequate knowledge of the beneficial and harmful effects of sun exposure, and had been using sunscreens regularly, and adopting other sun protective measures in their daily life. The levels of vitamin D were found to be deficient in both sunscreen users and those who had never used sunscreens. The difference between the two groups was statistically insignificant (60.67% vs 54.67%; P value>0.001). CONCLUSION: Population at large seems to be adequately informed about the beneficial and deleterious effects of sun exposure. Vitamin D levels are deficient in majority of our people, and there is a need to do larger surveys covering all parts of the country and give supplemental doses of vitamin D to those found deficient.