Can vitiligo cause a deficiency in Vitamin D?

Vitiligo is a skin condition closely related to skin pigmentation, characterised by the appearance of white patches on the skin. This phenomenon results from the selective loss of melanocytes, the cells responsible for the production of melanin, the pigment that gives skin its colour and plays a crucial role in protecting it from the sun's ultraviolet rays. In the absence of melanin, exposed areas are particularly susceptible to sunburn, melanomas, carcinomas and other UV-induced cellular damage. This is why fair skin is very vulnerable to the sun, although it is also important for darker skin to protect itself with a sunscreen.

Individuals suffering from vitiligo, who have depigmented areas, must be particularly vigilant when exposed to the sun.

Nevertheless, in addition to having beneficial effects on morale, exposure to the sun allows the body to synthesize vitamin D. From a mechanistic perspective, UVB rays convert 7-dehydrocholesterol in the epidermis into pre-vitamin D3. This then forms vitamin D3 through progressive thermal isomerisation before reaching the liver and being hydrolysed into 25-hydroxyvitamin D [25(OH)D], the circulating form. Subsequently, it is transported to the kidneys to undergo a second hydroxylation and become calcitriol 1,25(OH)2D, which is the active form of vitamin D. This plays a fundamental role in the body. It is particularly essential for bone health and contributes to the proper functioning of the immune system.

In this context, it is valid to question whether individuals affected by vitiligo, who avoid the sun, have a sufficient capacity to synthesise vitamin D. It's worth noting that we refer to a deficiency in vitamin D when the serum level is below 10 ng/mL, even though the recommended level is above 30 ng/mL. Several studies have investigated the risk of vitamin D deficiency in individuals with vitiligo, but have reached different conclusions. The results of three of these are outlined below.