Vitamin D Deficiency: A Neglected Truth in Iran

Vitamin D (vit D) is a fat-soluble steroidwhich includes two forms: vitD2 (ergocalciferol) and vit D3 (cholecalciferol).The former is provided from plant and the latter istaken from animal sources (Shao et al., 2012). VitD is obtained from natural synthesis in the skinand also from some dietary sources such as oilyfish, eggs, fortified products (dairy, cereals, soy),and oral supplements (Jolfaie et al., 2016, Kennelet al., 2010). Finally, it is activated biologicallyduring hydroxylation process in the liver andkidneys (Shao et al., 2012).Vit D has essential physiological functionsfor maintaining mineral homeostasis (Chung et al.,2011). Indeed, vit D deficiency can contribute toseveral musculoskeletal disorders, such as ricketsin children, osteomalacia, osteopenia, osteoporosis,and fractures in adults (Moher et al., 2001). Inaddition, the association between vit D deficiencyand many diseases including cancers, infections,autoimmune diseases, diabetes mellitus, andcardiovascular diseases have been studied (Hilgeret al., 2014, Norman, 2008). The normal level of25(OH)D (the dominant vit D metabolite incirculation representing vit D status) is considered20 ng/ml (50 nmol/L) and less than this value isclassified into the deficiency category(Christodoulou et al., 2013, DeLuca, 2004). Themost important factors in deficiency of vit D aredecreased sun exposure, insufficient vit D intake,and increase of age (Gaugris et al., 2005).Moreover, high risk of vit D deficiency has beenobserved in special groups and conditions such aschildren, pregnant and postmenopausal women, aswell as elderly people (Shao et al., 2012); diseasesassociated with fat mal-absorption (e.g., Crohn’sdisease) (Kennel et al., 2010); and disturbingconditions of parathyroid, liver, or kidneyfunctions (Kathleen Mahan et al., 2012).V