Researchers have found a link between autoimmune diseases and vitamin D deficiency. Since Vitiligo/Leucoderma is generally considered to be an autoimmune illness, people with the condition should consider getting tested for Vitamin D deficiency or insufficiency. Vitaman D-3 is the most important form of vitamin D for human health. It's difficult to get sufficient Vitamin D from food. We produce most of our requirement in our skin during exposure to the sun. People with Vitiligo often avoid sun exposure, because their depigmented patches lack melanin to protect them from sunburn and the risk of skin cancer (also, the tanning effect of sun exposure increases the contrast between the white patches and the normal skin, and thus increases the noticeability of the vitiligo) but completely avoiding sun exposure means you are almost certainly not getting enough vitamin D, which could make your condition get worse. The length of sun exposure needed to make enough vitamin D depends on the amount of melanin in your skin, and the amount of solar radiation where you live, but generally 20 minutes of sun exposure each day is enough. Dark-skinned people may need longer exposure. Any part of the skin can do the job; so if you want to protect your face from tanning you can cover it and expose your legs, for example.