Reviewer ’s report  
 
Title: Vitamin D Metabolites Across the Menstrual Cycle: A Systematic Review  
 
Version: 0 Date: 01 Oct 2018  
 
Reviewer: Santiago Palacios  
 
Reviewer's report:  
 
It is an interesting topic, although I think it would be best to know the influence of the levels of 
estradiol and progesterone throughout the cycle on 25 -OH-Vitamin D. The latter, could not be 
determined.  
And the fact is that the number of studies  and cases is small, for that reason I think that it has not 
been possible to reach a definitive conclusion. It would be interesting to see if there is any 
difference in age between the studied population, with groups of 18 to 35 years, and 36 to 47 
years.  
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are t he conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manuscript or would you recommend an  
additional statistical review?  
If an additional stati stical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
Not relevant to this manuscript  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
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