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Comparison of the Effect of Ceratonia siliqua L. (Carob) Syrup and Vitamin E on Sperm Parameters, Oxidative Stress Index, and Sex Hormones in Infertile Men: a Randomized Controlled Trial


Herbal products with an antioxidant capacity can boost male reproductive functions. The empiric use of Ceratonia siliqua (carob) for its antioxidant properties is common among infertile men in Iran and Turkey. The objective of this study is to investigate the effects of C. siliqua (carob) on semen parameters, oxidative stress markers, and pregnancy rate in a parallel randomized, controlled study. A total of 60 infertile men with oligozoospermia, asthenospermia, and teratospermia were recruited from April 2018 to March 2019. Participants were divided randomly into the following two groups: carob syrup twice a day or vitamin E 100 mg twice a day for 3 months. Semen analysis was performed and hormonal levels and stress oxidative markers were measured in each treatment arm after 3 months. The quality of semen parameters improved in the carob group compared with Vit E semen count (p = 0.04 Cohen’s d = .51), morphology (p = 0.001 Cohen’s d = .93) and motility parameters (p = 0.002 Cohen’s d = .90) were significantly higher in the carob group. No significant difference can be detected in post-treatment hormonal parameters and oxidative markers between groups, except for total antioxidant capacity(TAC) which was higher after post-treatment in carob group. A significantly higher pregnancy rate was found among the carob group. The administration of carob may be an effective agent for the improvement of semen parameters, probably related both to its involvement in the changing of testosterone level and to its antioxidant properties. Nevertheless, additional studies to evaluate the optimal dose and duration of treatment are needed. The trial has been registered in the Iranian Registry of Clinical Trials (Registration number: IRCT20171209037794N1.

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Data on the main outcomes will be available.



Ceratonia siliqua


Total antioxidant capacity


Reactive oxygen species


Body mass index


Follicle-stimulating hormone


Luteinizing hormone






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We appreciate the cooperation of the Research Deputy of the university, the head of Health Research Institute, and all study participants.


This research is funded by Vice Chancellery of Research and Technology of Babol University of Medical Sciences.

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Authors and Affiliations



PM participated in the conception, design of the study, and implementation of research project. MMR was urologist and helped to draft the manuscript. FM prepared carob syrup. NM collected blood samples from patients. SM and AD analyzed serum and semen. PM and MN performed the statistical analysis. All authors read and approved the final manuscript.

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Correspondence to Parvaneh Mirabi.

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The research project has received the confirmation of the Institution Ethics Committee (Babol University of Medical Sciences) with the number No.MUBABOL.HRI.REC.1396.179. The consent form of our patients was taken and is available.

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Not applicable.

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The authors declare that they have no competing interests.

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Aghajani, M.M.R., Mahjoub, S., Mojab, F. et al. Comparison of the Effect of Ceratonia siliqua L. (Carob) Syrup and Vitamin E on Sperm Parameters, Oxidative Stress Index, and Sex Hormones in Infertile Men: a Randomized Controlled Trial. Reprod. Sci. 28, 766–774 (2021).

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  • Ceratonia siliqua (carob)
  • Male infertility
  • Vitamin E
  • Oxidative stress
  • Pregnancy