Bell's palsy (BP) is the most prevalent acute mono-neuropathy associated with facial nerve failure, accounting for 60-75% of all occurrences of facial paralysis. The primary pathophysiological mechanism leading to BP is recognized as the confinement of the facial nerve within the facial canal, caused by edema. The link between vitamin D and neurological disorders has drawn more scientific attention in recent years, and vitamin D plays a role as a neuro-immuno-modulator. While some studies suggest an association between vitamin D and the incidence of BP, others report no significant impact. This systematic review aims to critically assess the relationship between vitamin D levels and the severity of BP.
