Vitamin D deficiency is a very common problem. In some communities, for example the British South Asian community it prevalence is near on 100%. Vitamin D replacement is advised. This usually involves using a loading dose od 300,000 unit of Vitamin D (many regimens / protocols exist for this), followed by a maintenance dose which usually ranges from 800 to 1600  i.u per day. Occasionally larger doses are required.

 

http://www.nejm.org/doi/full/10.1056/NEJMra070553