Abstract
BackgroundBoth vitamin D and iron deficiencies are widespread globally, and a relationship between these deficiencies has been suggested. However, there is a paucity of randomised controlled trials assessing the effect of vitamin D supplementation on iron status.PurposeWe aimed to investigate whether 16 weeks of daily vitamin D3 supplementation had an effect on serum ferritin, haemoglobin, serum iron and transferrin saturation.MethodsOverall, 251 participants from South Asia, Middle East and Africa aged 18–50 years who were living in Norway were randomised to receive daily oral supplementation of 10 μg vitamin D3, 25 μg vitamin D3, or placebo for 16 weeks during the late winter. Blood samples from baseline and after 16 weeks were analysed for serum 25-hydroxyvitamin D (s-25(OH) D), serum ferritin, haemoglobin and serum iron. In total, 214 eligible participants completed the intervention (86 % of those randomised). Linear regression analysis were used to test the effect of vitamin D3 supplementation combined (10 or 25 μg) and separate doses 10 or 25 μg compared to placebo on change (T2-T1) in each outcome variable adjusted for baseline s-25(OH)D values.ResultsThere was no difference in change in the levels of s-ferritin (1.9 μg/L, 95 % CI: -3.2, 7.0), haemoglobin (-0.02 g/dL, 95 % CI: -0.12, 0.09), s-iron (0.4 μg/L, 95 % CI: -0.5, 1.3) or transferrin saturation (0.7 %, 95 % CI: -0.6.1, 2.0) between those receiving vitamin D3 or those receiving placebo. Serum 25-hydroxyvitamin D increased from 29 nmol/L at baseline to 49 nmol/L after the intervention, with little change in the placebo group.ConclusionsIn this population of healthy ethnic minorities from South Asia, the Middle East and Africa who had low vitamin D status, 16 weeks of daily supplementation with 10 or 25 μg of vitamin D3 did not significantly affect the haemoglobin levels or other markers of iron status.Electronic supplementary materialThe online version of this article (doi:10.1186/s12937-016-0192-7) contains supplementary material, which is available to authorized users.
Highlights
Iron deficiency remains one of the most severe and important nutritional deficiencies in the world
The aim of the present study was to determine whether 16 weeks of daily vitamin D3 supplementation (10 or 25 μg/d) vs placebo would affect the iron status in a multi-ethnic immigrant population during the late wintertime
We have recently reported that vitamin D deficiency and secondary hyperparathyroidism (SHPT) is prevalent among non-western immigrants in Norway, it documented that marrow fibrosis has been reported in cases of primary and secondary hyperparathyroidism with very high levels of parathyroid hormone (PTH)
Summary
Iron deficiency remains one of the most severe and important nutritional deficiencies in the world. This deficiency affects more than 30 % of the world’s population, impacting an estimated 2 billion people [1, 2]. A co-existence of vitamin D and iron deficiencies has been reported, and an association between low serum 25-hydroxyvitamin D (s- 25(OH) D) and low levels of. Both vitamin D and iron deficiencies are widespread globally, and a relationship between these deficiencies has been suggested. Purpose: We aimed to investigate whether 16 weeks of daily vitamin D3 supplementation had an effect on serum ferritin, haemoglobin, serum iron and transferrin saturation
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