Vitamin D deficiency/insufficiency from childhood to adulthood: Insights from a sunny country

Vitamin D is known to be a key regulator of bone metabolism and is associated with muscle strength. Vitamin D deficiency is widely prevalent worldwide. In adults, vitamin D deficiency has been implicated in numerous health conditions including osteoporosis, cancer, diabetes, and autoimmune diseases. Considerable changes have occurred in lifestyles and childhood activities in the past years. Studies have shown that the children population is at high risks of vitamin D deficiency. The objective of this study was to learn about the extent of vitamin D deficiency in children worldwide and especially in sunny country like Israel. In this article we reviewed the extent and severity of vitamin D deficiency worldwide and especially in Israel, through a very comprehensive review of previous reports and research studies done during the last years. We found reports on vitamin D deficiency in children, which was associated with metabolic syndromes and obesity. It was more prevalent in children who spend less time on outdoor activities, in obese children, and in cases when there was imbalance between nutritional intakes and requirements. Vitamin D deficiency is common even in children living in sunny places like Israel. Health professionals should be aware of the fact that although vitamin D deficiency is prevalent in the elderly population, it is also common in children, and can be associated with different illnesses. We encourage supplementation of vitamin D to special populations (pregnant and lactating women, infants, and high risk groups). We also encourage implementation of international food fortification programs.

Single nucleotide polymorphisms in the vitamin D pathway associating with circulating concentrations of vitamin D metabolites and non-skeletal health outcomes: Review of genetic association studies

Polymorphisms in genes encoding proteins involved in vitamin D metabolism and transport are recognised to influence vitamin D status. Syntheses of genetic association studies linking these variants to non-skeletal health outcomes are lacking. We therefore conducted a literature review to identify reports of statistically significant associations between single nucleotide polymorphisms (SNP) in 11 vitamin D pathway genes (DHCR7, CYP2R1, CYP3A4, CYP27A1, DBP, LRP2, CUB, CYP27B1, CYP24A1, VDR and RXRA) and non-bone health outcomes and circulating levels of 25-hydroxyvitamin D (25[OH]D and 1,25-dihydroxyvitamin D (1,25[OH]₂D). A total of 120 genetic association studies reported positive associations, of which 44 investigated determinants of circulating 25(OH)D and/or 1,25(OH)₂D concentrations, and 76 investigated determinants of non-skeletal health outcomes. Statistically significant associations were reported for a total of 55 SNP in the 11 genes investigated. There was limited overlap between genetic determinants of vitamin D status and those associated with non-skeletal health outcomes: polymorphisms in DBP, CYP2R1 and DHCR7 were the most frequent to be reported to associate with circulating concentrations of 25(OH)D, while polymorphisms in VDR were most commonly reported to associate with non-skeletal health outcomes, among which infectious and autoimmune diseases were the most represented.