Vitamin d is normally obtained from the diet  or produced by the skin from the ultraviolet energy of the sun . As more people avoid the sun exposure.
Vitamin d supplement become even more necessary to ensure that your body receives an adequate supply

Benefits of vitamin d3:

Strengthens the bones
Strengthens the teeth
Might prevent certain types of cancers
May improve brain function 
It boosts your mood
Can aid in weight loss
Can lower the risk of rheumatoid arthritis
Lower the tisk of type 2 diabetes
Support colon health