Does Vitamin D deficiency cause hair loss?
Yes! Hair loss and rickets are the primary symptoms of vitamin D deficiency so this is a good vitamin to take if you have hair loss caused by nutritional causes; however, the most common cause of hair loss is genetic.
A study published in the Journal of Endocrinology back in 2002 points to vitamin D fostering hair growth in mice. How that relates to humans is not known to me, but it’s worth a read if you’re interested — Vitamin D3 analogs stimulate hair growth in nude mice