Vitamin D Supplementation and Male Infertility: The CBG-study a Randomized Clinical Trial

Summary

Today, it is evident that vitamin D (VD) has more widespread effects than the classical actions related to bone mineralization and calcium homeostasis1. VD deficiency results in impaired reproductive performance in various species of animals, and recently the investigators have shown that the VD receptor (VDR), activating (CYP2R1, CYP27A1, CYP27B1) and inactivating (CYP24A1) enzymes are expressed in the human testis, epididymis, seminal vesicle, prostate and spermatozoa. Our following functional studies showed that VD increases intracellular calcium in mature spermatozoa, and hence may be important not only for spermatogenesis but also for sperm maturation. A new, and yet unpublished cross sectional study of 300 young healthy Danish men showed that men with lower levels of serum VD have significantly lower number of normally developed and motile spermatozoa. Hitherto, most cases of male infertility have been classified as "idiopathic", and infertile couples have been referred to symptomatic treatment at infertility clinics. These fertility treatments are often physically demanding for the female partner as well as expensive for the health care system. Any treatment that might improve semen quality of involuntary infertile men would be beneficial both for the infertile couples and the society in general. Our findings that VD may play a role for human semen quality have not yet been tested clinically. However, if VD supplementation proves efficient this opens for the first time for a causal, safe and cheap treatment of at least some cases of "idiopathic" impaired semen quality. The investigators believe our new human data supported by the results from the VD deficient and VDR KO animal studies and the high proportion of VD deficient Danish men provide sufficient evidence to initiate a randomized clinical trial of VD supplementation to infertile men. Infertile men have also have unfavorable altered levels of sex hormones and higher mortality than fertile men. Since VD deficiency is associated with increased mortality, regulation of aromatase, immune system, bone metabolism, glucose metabolism, cardiovascular system etc. our suggested clinical trial may also be able to evaluate several secondary endpoints in addition to the potential effect on semen quality.

Timeline

Start

2011-02

Primary completion

2014-12

Completion

2016-05

Publications

• Yahyavi SK, Toft FB, Probst-Drejer B, Boisen IM, Priskorn L, Jorgensen N, Juul A, Blomberg Jensen M. High Seminal Fluid Calcium Is Associated With Higher Sperm Concentration in Infertile Men and Men From the General Population. Andrology. 2026 Jul;14(5):1261-1271. doi: 10.1111/andr.70172. Epub 2026 Jan 14.
• Wall-Gremstrup G, Holt R, Yahyavi SK, Jorsal MJ, Juul A, Jorgensen N, Blomberg Jensen M. High-dose vitamin D3 supplementation shows no beneficial effects on white blood cell counts, acute phase reactants, or frequency of respiratory infections. Respir Res. 2024 Jan 4;25(1):11. doi: 10.1186/s12931-023-02642-9.
• de Ligny W, Smits RM, Mackenzie-Proctor R, Jordan V, Fleischer K, de Bruin JP, Showell MG. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2022 May 4;5(5):CD007411. doi: 10.1002/14651858.CD007411.pub5.
• Holt R, Petersen JH, Dinsdale E, Knop FK, Juul A, Jorgensen N, Blomberg Jensen M. Vitamin D Supplementation Improves Fasting Insulin Levels and HDL Cholesterol in Infertile Men. J Clin Endocrinol Metab. 2022 Jan 1;107(1):98-108. doi: 10.1210/clinem/dgab667.
• Juel Mortensen L, Lorenzen M, Jorgensen A, Albrethsen J, Jorgensen N, Moller S, Andersson AM, Juul A, Blomberg Jensen M. Possible Relevance of Soluble Luteinizing Hormone Receptor during Development and Adulthood in Boys and Men. Cancers (Basel). 2021 Mar 16;13(6):1329. doi: 10.3390/cancers13061329.
• Juel Mortensen L, Lorenzen M, Jorgensen N, Andersson AM, Nielsen JE, Petersen LI, Lanske B, Juul A, Hansen JB, Blomberg Jensen M. Possible link between FSH and RANKL release from adipocytes in men with impaired gonadal function including Klinefelter syndrome. Bone. 2019 Jun;123:103-114. doi: 10.1016/j.bone.2019.03.022. Epub 2019 Mar 23.
• Blomberg Jensen M, Lawaetz JG, Petersen JH, Juul A, Jorgensen N. Effects of Vitamin D Supplementation on Semen Quality, Reproductive Hormones, and Live Birth Rate: A Randomized Clinical Trial. J Clin Endocrinol Metab. 2018 Mar 1;103(3):870-881. doi: 10.1210/jc.2017-01656.
• Blomberg Jensen M, Gerner Lawaetz J, Andersson AM, Petersen JH, Nordkap L, Bang AK, Ekbom P, Joensen UN, Praetorius L, Lundstrom P, Boujida VH, Lanske B, Juul A, Jorgensen N. Vitamin D deficiency and low ionized calcium are linked with semen quality and sex steroid levels in infertile men. Hum Reprod. 2016 Aug;31(8):1875-85. doi: 10.1093/humrep/dew152. Epub 2016 Jun 19.

Drugs

Indications