Question: what are three functions of vitamin d?
Answer: Immunity. Vitamin D receptors are found all over the body, including the immune cells. ... 
Bones. It's well-documented that vitamin D is essential for the proper absorption of calcium, and it's been shown to greatly reduce fracture risk in two ways. ... 
Muscles. ... 
Lungs. ... 
Heart. ... 
Kidneys. ... 
Mood. ... 
Weight Loss.