Table 1. Summary of studies on vitamin D and BPPV.

BPPV: Benign paroxysmal positional vertigo

Article	Study design	Study characteristics	Main findings
Algarni et al. [21]	Systematic review and meta-analysis	Sample size = 1015; Consisting of three case-control studies and four cohort studies	No difference in vitamin D levels between BPPV cases and controls; and low vitamin D levels are associated with recurrence
Inan et al. [22]	Retrospective case-control study	Sample size = 104 with 52 BPPV cases and 52 controls	Higher rate of vitamin D deficiencies in BPPV patients
Ding et al. [23]	Cross-sectional study	Sample size = 522 with 174 BPPV cases and 348 normal individuals	Low vitamin D levels in 62.1% of BPPV cases; and low levels of vitamin D in recurrent BPPV
Sarsitthithum et al. [24]	Prospective-cross sectional study	Sample size = 137 with 69 BPPV cases and 68 controls	Low serum 25(OH)D in BPPV patients while no difference in vitamin D levels between recurrent and other patients
Meghji et al. [25]	Retrospective review	Sample size = 339 diagnosed cases of BPPV	BPPV shows seasonal variability with vitamin D being lower in winters
Goldschagg et al. [26]	Short communication	Sample size = 680 with 158 cases of BPPV, 221 cases of vestibular disorders, and 301 cases of non-vestibular disorders	No difference in vitamin D levels between BPPV patients and others