Abstract
Vitamin D supplementation and hemoglobin: dosing matters in prevention/treatment of anemia
Highlights
To the Editor: Arabi et al report in the recent systematic review and meta-analysis of the effect of vitamin D supplementation on hemoglobin concentration that supplementation with vitamin D had no significant effect on hemoglobin and ferritin levels, while positive effects on transferrin saturation and iron status were observed [1]
There is concern that the conclusion of this meta-analysis “... vitamin D had no significant effect on hemoglobin levels” is not meaningful based on the wide diversity of studies included
Did the authors consider assessment of the total vitamin D dose in each of the studies, and separate analysis of the trials in anemic patients? The Table below confirms the wide variability in total dose and duration in these randomized clinical trials, which makes it challenging to discern an impact of vitamin D on hemoglobin in anemic patients
Summary
To the Editor: Arabi et al report in the recent systematic review and meta-analysis of the effect of vitamin D supplementation on hemoglobin concentration that supplementation with vitamin D had no significant effect on hemoglobin and ferritin levels, while positive effects on transferrin saturation and iron status were observed [1]. The potential beneficial impact of vitamin D on hemoglobin in patients with anemia was not separately examined. Did the authors consider assessment of the total vitamin D dose in each of the studies, and separate analysis of the trials in anemic patients? It has clearly been documented that high-dose vitamin D is required for hepcidin suppression, which is required for optimal increase in endogenous erythropoiesis and subsequent increase in hemoglobin in anemic patients who have high hepcidin levels and anemia of inflammation or chronic kidney disease [2–7].
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