Meta-analysis of vitamin D supplementation and hemoglobin concentration: methodological faults obscure the interpretation of the data

Alireza Zimorovat,Mohsen Mohammadi-Sartang,Reza Barati-Boldaji,Hamidreza Raeisi-Dehkordi

doi:10.1186/s12937-021-00681-w

Abstract

We read the review by Arabi et al. with great interest which tried to examine the effects of vitamin D supplementation on hemoglobin concentration. It seems that the article suffers from fundamental methodological issues and the conclusions are likely to be erroneous. In this regard, we would like to ask the authors to address the mentioned limitations and to update the analysis in order to provide robust and trustful results. We are concerned that such meta-analyses may lead to the biased findings and conclusions.

Highlights

We read the review by Arabi et al with great interest which tried to examine the effects of vitamin D supplementation on hemoglobin concentration
* Correspondence: hamidreza92nut@gmail.com 1Nutrition and Food Security Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran 2Department of Nutrition, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Full list of author information is available at the end of the article comparison)
It is stated that studies which used oral vitamin D supplementation were included, we noticed that they included studies which have used parenteral or enteral vitamin D supplementation

Summary

Introduction

We read the review by Arabi et al with great interest which tried to examine the effects of vitamin D supplementation on hemoglobin concentration. * Correspondence: hamidreza92nut@gmail.com 1Nutrition and Food Security Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran 2Department of Nutrition, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Full list of author information is available at the end of the article comparison). One study which used enteral vitamin D supplementation for critically ill patients [5] was included in the meta-analysis which is against their inclusion criteria as well.

Results

Conclusion