Vitamin D and calcium are considered crucial for the treatment of bone diseases. Both vitamin
D and calcium contribute to bone homeostasis but also preserve muscle health by reducing the risk
of falls and fractures. Low vitamin D concentrations result in secondary hyperparathyroidism and contribute
to bone loss, although the development of secondary hyperparathyroidism varies, even in patients
with severe vitamin D deficiency. Findings from observational studies have shown controversial
results regarding the association between bone mineral density and vitamin D/calcium status, thus
sparking a debate regarding optimum concentrations of 25-hydroxyvitamin D and calcium for the best
possible skeletal health. Although most of the intervention studies reported a positive effect of supplementation
with calcium and vitamin D on bone in patients with osteoporosis, this therapeutic approach
has been a matter of debate regarding potential side effects on the cardiovascular (CV) system. Thus, the
aim of this review is to consider the current evidence on the physiological role of vitamin D and calcium
on bone and muscle health. Moreover, we provide an overview on observational and interventional studies
that investigate the effect of vitamin D and calcium supplementation on bone health, also taking into
account the possible CV side-effects. We also provide molecular insights on the effect of calcium plus
vitamin D on the CV system.
