Smell Regions in Patients with Vitamin D Deficiency: An MRI Evaluation.

 We investigated the effects of vitamin D deficiency in the peripheral and central smell regions by magnetic resonance imaging (MRI).  This retrospective study included 29 patients (12 males, 17 females) with 25-dihydroxy vitamin D3 [25(OH) D ] deficiency (group 1) and 34 subjects without 25(OH) D deficiency (14 males, 20 females) (group 2). Using cranial MRIs, the peripheral (olfactory bulb [OB] volume and olfactory sulcus [OS] depth) and central (insular gyrus and corpus amygdala) smell regions were evaluated.  The OB volume and OS depth values of the 25(OH) D3 deficiency group were significantly lower than those of the control group (  < 0.05). For the central smell regions, the insular gyrus and corpus amygdala areas of the 25(OH) D3 deficiency group were nonsignificantly lower than those in the control group (  > 0.05). There were positive correlations between OB volumes, OS depths, and insular gyrus and corpus amygdala areas bilaterally in the 25(OH) D3 deficiency group separately and in all subjects (groups 1 and 2) (  < 0.05). In the 25(OH) D3 deficiency group, as the 25(OH) D3 values became lower, the insular gyrus area values decreased bilaterally (  < 0.05). In females, the corpus amygdala area values were lower than in males (  < 0.05).  Since vitamin D3 deficiency affected the peripheral and central smell regions negatively, we recommend evaluating patients' vitamin D levels as a health policy to prevent vitamin D3 deficiency-related cranial smell region problems. Moreover, sunlight exposure is very important to increase vitamin D levels, and the public should be informed about this topic.