Table 2: Zn dosages and sperm parameters of the included studies.

From: Zinc levels in seminal plasma and their correlation with male infertility: A systematic review and meta-analysis

 Zn doseSperm concentrationSemen volumeSperm viabilitySperm normal morphologySperm abnormal morphologySperm countSperm motility
Hadwan MH 2012zinc sulfate 220 mg + + +
Hadwan MH 2014zinc sulfate 220 mg + + ++
Haidar M 2013zinc sulfate 220 mg++  +
Wong WY 2002zinc sulfate 66 mg+  +
Li Y 2013NI  +   +
Zhang DT 2003zinc gluconate 10 ml++ ++  
  1. NI, not indicated in the study; +, a significant difference between before and after zinc supplementation; −, no significant difference between before and after zinc supplementation.