 [ Symptoms ] can a deficiency in vitamin d cause hair loss [ Disease ] hi yes it can just see the info below vitamin d deficiency because most people spend their time in doors behind a desk or on the couch a surprisingly high percentage of the population have insufficient levels of vitamin d in their body vitamin d is synthesized in the skin through exposure to uv rays  studies have shown that low vitamin d causes hair loss too much vitamin d high levels of vitamin d can also cause hair loss which is why it is important to have the right balance of vitamin d and as you can see it works both ways do hope this helps you good luck