I had talked about Vitamin D deficiency very recently in this post . One of the blog readers, Roshni, left this comment which I think is worth reading.
I have vitamin D deficiency. Against the requirement of at least 30, my
vitamin D was 3.4. My doc is giving me injections for the deficiency and
has asked me to be very careful for sometime as my bones are brittle
and can fracture easily. Vitamin D deficiency is truly very
common today (particularly after you start working as most people spend
the whole day indoors). My suggestion to anyone who has this routine of
getting up, exercising in the house and then going to work, to get your
vitamin D checked.
I would again like to assert that going outdoors or having a house which has plenty of ventilation is a good idea as well as a proper balanced diet is very necessary to combat such deficiencies.