Benign paroxsymal positional vertigo is characterised by brief attacks of dizziness brought on by a change in head position. It is thought to occur from debris entering the balance mechanism in the middle ear.
Observational studies links these attacks to osteoporosis and vitamin D deficiency.
A trial of oral supplementation with vitamin D and calcium appears to give fewer attacks of the dizzy episodes compared to no treatment over the course of the next year.
My comment: The Epley movements are also a treatment but they need to be given in person and by someone who knows how. You tube videos of this are available.