The overall impact of Vitamin D
There are receptors for Vitamin D in most of the organ systems of the body. Vitamin D has a range of effects in many organs; those with low Vitamin D have 7% higher mortality.
Low Vitamin D is associated with greater chance of developing many conditions or poor clinical outcomes.
In osteoporosis, vitamin D has direct effects on calcium absorption from the gut, and osteoporosis drugs do not work as effectively in sub-optimum Vitamin D level.