What are the causes of vitamin d deficincy? and are the treatments?

Lack of sun and diet: Vitamin d deficiency is fairly common and important to treat. Sun exposure can improve vitamin d levels. Diet can be lacking in vit d--(eg if you are not a milk drinker- milk is fortified with vitamin d). Over the counter supplements are widely available (make sure to take vitamin d3- to assure maximum benefit) up to 5000 units- probably need at least 1000 units per day.