Vitamin D is necessary to keep your immune system functioning properly and can help everything from high blood pressure, cancer and many auto immune issues.  It also assists with bone strength.  Vitamin D is fat-soluble which means you need to have fat in your diet in order to have it absorb efficiently. 

Low vitamin D can cause many issues like depression, fatigue, weak muscles, weak bones, Rickets (bone deformity in kids) and many other issues.We produce Vitamin D when we get ultraviolet B rays (UVB).  UVB interacts with 7-dehydrocholesterol (7-DHC) in our skin.  Even though we get this from the sun, sometimes the exposure isn’t enough and we need to take a supplement even in the summer months.  Caucasians need less sun times during the day because of the light pigment of the skin but for darker skin individuals UV alone may not be enough and can suffer from low doses of Vit D.  

Sun exposure also puts each person under risk of skin cancer, photoaging (skin aging), cataracts and eye damage.  If you are at low risk of skin cancer and get checked regularly then you should be okay with sun exposure but it is recommended to take supplements in order to get what is needed.  Recommendations are 600 IU for people ages 1-70 and 800 IU a day for 70 and older.  Kids under a year old should only get 400 IUs per day.  

Foods high in Vitamin D are:

It is also recommended to take vitamin B along with Vitamin D to help with absorption.