Some studies have suggested a link between vitamin D and headache; however, the underlying physiological mechanisms are unclear. We aimed to summarize the available evidence on the relationship between vitamin D and the various subtypes of primary headaches, including migraines and tension-type headaches. All articles concerning the association between primary headache and vitamin D published up to October 2019 were retrieved by searching clinical databases, including: EMBASE, MEDLINE, PubMed, Google scholar, and the Cochrane library. All types of studies (i.e., observational, cross-sectional, case-control, and clinical trials) were included. We identified 22 studies investigating serum vitamin D levels in association with headaches. Eight studies also evaluated the effect of vitamin D supplementation on the various headache parameters. Among them, 18 studies showed a link between serum vitamin D levels and headaches, with the strongest connection reported between serum vitamin D levels and migraine. Overall, there is not enough evidence to recommend vitamin D supplementation to all headache patients, but the current literature indicates that it may be beneficial in some patients suffering headaches, mainly migraineurs, to reduce the frequency of headaches, especially in those with vitamin D deficiency.

Regarding the high prevalence of vitamin D (25(OH)D) deficiency in the population and its possible association with ear diseases, we aimed to investigate the 25(OH)Dserum level in patients with subjective, nonpulsating tinnitus and its effect on tinnitus severity. The study included 201 tinnitus patients and 99 controls. Patient clinical information, including tinnitus characteristics and severity according to Tinnitus Handicap Inventory (THI), loudness assessed by Visual Analogue Scale (VAS), audiometry, and the blood level of vitamin D, was recorded. The level of 25(OH)D in tinnitus patients was significantly decreased compared with the controls (19.86 ± 7.53 and 27.43 ± 8.85 ng/ml, respectively; P value < 0.0001). More patients in the tinnitus group were deficient in vitamin D, compared with the controls (50.7% vs. 22.2% respectively, p < 0.0001). Tinnitus patients with a lower serum level of 25(OH)D (≤15 ng/dl) were significantly younger, had a higher degree of tinnitus severity measured with THI and VAS scales, had higher triglyceride and TSH levels, and a lower HDL level compared with individuals who had higher 25(OH)D level (>15 ng/dl). There was a strong correlation between the 25(OH)D level and THI. Our findings suggest that a large proportion of tinnitus patients suffers from vitamin D deficiency and that the vitamin D level correlates with tinnitus impact. We recommend a vitamin D assessment for all tinnitus patients.

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