White spots on the legs, especially if they are increasing, could indicate three conditions – vitiligo, leukoderma or a vitamin deficiency. In the case of the first two diseases, there is little that can be done, as these are autoimmune disorders of the system. Vitamin deficiency that causes black spots is usually attributable to a lack of vitamin B 12 in the diet and the condition will go away once you start increasing the levels of B12.
Autoimmune disorders are diseases that are not caused by infections but by the body. To be exact, an autoimmune disorder occurs when the immune system is hypersensitive and starts to attack healthy tissue, and also generates an inflammatory response at the slightest provocation. In the case of vitiligo and leukoderma, the immune system attacks the skin cells killing off the melanocyte cells that produce the pigment called melanin. In the absence of melanin, there is a distinct lack of color and protection to the skin causing white patches to appear on the body. If the spots are very small then this can be ruled out as possible problem. Small patches of white spots are still caused by a lack of melanin but they are not caused by an autoimmune disorder but because of the lack of vitamin B 12 – required for the DNA synthesis of all cells. Vitamin B12 is the most complex and important of all the vitamins because of its role in cellular division and the synthesis of DNA. It is in fact an entire stack of vitamins in itself making it molecularly quite complex. The bigger problem lies in the fact that is quite difficult to acquire this vitamin from dietary sources, as the absorption of B12 in the body is not very efficient. However, the body makes up for this by having the ability to store almost a few years worth of the vitamin in the liver and continuously recycling it. However, over a period of time, the reserves deplete and have to be resupplemented by using vitamin B supplements.
The best dietary sources of B12 come from animal sources like milk, eggs and meat. This might be problematic to obtain if you are a vegetarian, so try to have a lot of dairy products. If you are vegan and any animal sources are a problem, then you need to take vitamin B12 supplements, as there are no plant sources that can give you this vitamin.