The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometers) thick under the oceans(oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).
The problem behind your itchy skin might be insufficient vitamin intake. There are a number of vitamins that promote the hydration and healthiness of your skin. A shortage in these could trigger itchiness, dry skin and other skin conditions. Alternatively, an overdose of such vitamins might also lead to itchy skin.
Itchy skin can develop for many reasons. It can occur with or without a rash, in small areas or the whole body. Identifying the cause is important to ensure proper treatment. While there are several potential causes of itchy skin, it has not been directly linked to a vitamin B-12 deficiency. However, vitamin B-12 is important to healthy skin and may be a potential treatment for eczema.