EN / DA
Photo: Pexels
Environment and sustainability

Sterile men with bone-like testicles

Semen quality around the world remains at a low point, and this situation seems especially serious in Denmark and the other countries in northern Europe. Experts point to chemicals and poor lifestyles as causes. New Danish-American research shows that vitamin D and calcium deficiencies among infertile men are closely linked to semen quality and that cells in the testicles of these men have more in common with bone cells than was previously thought.

During the past 20 years, hopeful young men have been subjected to scientific wrangling on the reasons for the poor quality of their semen. Northern Europe is severely affected, and in Denmark nearly one in seven men has sufficient difficulty in getting a partner pregnant that they require treatment. Unfortunately, there has been no treatment for men. However, a Danish-American research team hopes to help men soon. The first results of their Copenhagen Bone Gonadal Study have been published in the journal Human Reproduction.

“Our results show that infertile men with a lower blood concentration of vitamin D have poorer semen quality. Previously, we saw the same link in men with normal semen quality. However, this is the first time that we can demonstrate that low blood levels of vitamin D and calcium also appear to affect the semen quality of men who have difficulty in having children,” explains Martin Blomberg Jensen from the Division of Bone and Mineral Research at Harvard University and the Department of Growth and Reproduction at Rigshospitalet, where the trials have been carried out and analysed.

Doubly active sperm cells

“The interesting thing is that we and other researchers have been able to demonstrate a link between calcium and vitamin D deficiencies and semen quality in animal studies. It is therefore natural to conclude that there is also a link between calcium and vitamin D and childlessness,” adds Martin Blomberg.

The trial tested the semen quality of 1427 infertile men and analysed their blood for calcium and vitamin D along with their hormone levels such as testosterone. The results were loud and clear. The sperm cells of men with a high blood concentration of vitamin D were up to twice as active as the semen cells of men with a low level of vitamin D.

“Most people think about bones in connection with vitamin D and calcium. Our hypothesis is based on the fact that some of the cells present in the testicles can begin to act as bone-like cells. We will therefore investigate bone factors that are released into the bloodstream and how they affect other organs and test whether drugs used for bone-related conditions also regulate testicular function.”

A completely new approach

Researchers were, however, surprised to discover that infertile men with low levels of calcium in their bloodstream had more mobile semen cells. This differed from the results of previous studies, and this led researchers to examine more closely the regulating mechanisms among infertile men and men with normal semen quality.

“We should always be careful not to jump to conclusions too early because, even if the blood levels of vitamin D and calcium and semen quality are clearly linked, determining the cause or the consequences may not be possible. However, this is big news if it turns out that taking vitamin D supplements can improve a man’s ability to father children,” says Martin Blomberg.

This is why this Danish-American research collaboration, with institutions such as Rigshospitalet, the University of Copenhagen and the group of renowned bone researcher Beate Lanske at Harvard University, is further investigating the link between the two different parts of the human body, gonads and bones, in a major placebo-controlled pharmaceutical trial that is part of the Copenhagen Bone Gonadal Study.

“Our demonstration of the link between vitamin D in the blood and semen quality was the basis for this unique collaboration. In the first stage, we will examine whether giving vitamin D to infertile men can improve their semen quality. However, the subsequent more basic research will be used to improve understanding and ultimately identify new treatment for male infertility.”

“This is just the beginning of a whole new approach to testicular research. In any case, we are convinced that the best news for us and patients is in front of us and starts with the effect of vitamin D supplements versus a placebo effect in infertile men,” concludes Martin Blomberg.

Blomberg Jensen M, Gerner Lawaetz J, Andersson AM, Petersen JH, Nordkap L, Bang AK, Ekbom P, Joensen UN, Prætorius L, Lundstrøm P, Boujida VH, Lanske B, Juul A, Jørgensen N. Vitamin D deficiency and low ionized calcium are linked with semen quality and sex steroid levels in infertile men. Human Reproduction 2016;31(8):1875–85. doi: 10.1093/humrep/dew152.

In 2009, the Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark received support from the Novo Nordisk Foundation for the project “Kan D-vitamintilskud forbedre sædkvaliteten og kønshormonprofilen hos mænd med stærkt nedsat sædkvalitet.”