Objective: To evaluate the effects of Ramadan  fasting on hematological data in athletes through a systematic appraisal of the literature.
Design: Systematic review
Data sources: The entire content of two databases, PubMed/MEDLINE and Web of Science Eligibility criteria for selecting studies: Ramadanrelated measurements of any hematological indices in athletes were considered. Both single-group pre-post with and without a
control group studies

conducted in athletes and published in English language before December 31, 2018 were
included.
Study  appraisal:

The  methodological  quality  of  the  studies  identified  was
 assessed  using
‘QualSyst’.
Results:
Of nine selected articles, eight were of moderate quality and only one was of strong
quality.
The main problem to date has been a lack of

appropriate controls. Compared to before Ramadan, hematocrit and hemoglobin values increased in three studies, decreased in
one study and did

not change in one study during Ramadan fasting.
Another study reported increased hematocrit and a puzzling decrease
of hemoglobin
during

as compared to before Ramadan fasting. In most studies, blood platelet counts and the limited number of immune function used
to date remained

unchanged.
Conclusions:

All reported changes in hematological indices remained within the normal reference range of the laboratory. Therefore, regular
training can continue safely during Ramadan fasting from a hematological view point.