Vitamin D Deficiency Linked to Human Infertility

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itamin D is one of the most important building blocks of our immune system. Nothing new here. There is tons of research that shows the different ways in which people could take vitamin D to strengthen their immune systems, but most if not all of it concludes that daily exposure to UV-B rays for periods of time ranging between 10-20 minutes provides the body with enough vitamin D to fight disease. Perhaps this is new for you. Optimum levels of Vitamin D also support absorption of calcium, which in turn increases bone health, which prevents osteoporosis and diabetes.

Now, new research conducted by Austrian physicians demonstrates that vitamin D is also responsible for a healthy reproductive system and for increased fertility. The absence of optimum levels of vitamin D, however, cause infertility in both men and women. A lack of vitamin D in the body promotes hormonal imbalances in both groups and these alterations cause men to produce less testosterone and women to produce more. The consequences are lower quality semen in men. In women low levels of vitamin D often lead to too much testosterone, which therefore could increase the risk of infertility.

Vitamin D receptors, also known as VDR’s as well as vitamin D metabolizing enzymes are found in the reproductive tissue of women and men. Some of the research shows that lower levels of Vitamin D in females (low 25-hydroxyvitamin D (25(OH)D) were associated with obesity and disturbances of the metabolism and the endocrine system.

The abundance of Vitamin D, they found, results in improvements in menstrual frequency in those women. Also, high 25(OH)D levels are associated with better semen quality  might increase testosterone levels. “ Mounting evidence suggests that hypovitaminosis D is linked to an increased risk for cancer 2, autoimmune diseases, diabetes and cardiovascular diseases 1-3 indicating the importance of sufficient vitamin D levels,” says the report. They also found that vitamin D also modulates reproductive processes in women and men.

Today, most female infertility is caused by what doctors call polycystic ovary syndrome or PCOS. Meanwhile, male infertility is attributed to environmental factors which is responsible for an all time low quality of semen, with concentrations well below healthy levels. At least 20% of young men have sperm concentration below what is expected  and 40% have sperm concentrations inferior to what is considered optimal for fertility. The consulted literature suggests that many adverse aspects of male aging are a consequence of decreased levels of  testosterone, most likely due to the lack of vitamin D.

Vitamin D is what researches call a steroid hormone. The way this substance acts in the body occurs through  a precursor known as 7-dehydrocholesterol. Here comes the role of UV-B solar rays. These rays cause the precursor to convert into vitamin D3 which is then transported around the body by the vitamin D binding protein. According to the study, 80-90% of the vitamin D used by the body comes from sunlight induced production in the skin. That is why it is monumentally important to expose our bodies to sunlight on a daily basis. The more we are able to take in sun rays for safe periods of 10-20 minutes a day, the more vitamin D the body will produce naturally and the stronger our immune systems will be. The absence of naturally produced vitamin D can be substituted with vitamin D supplements. Humans must intake between 4000 and 5000 UI of vitamin D daily through supplementation in order to keep healthy levels in their bodies.

As for the role of vitamin D in reproductive tissues, the research shows that vitamin D receptors or VDR’s are all over those tissues, which doctors believe means that vitamin D plays an important role in the human reproductive system. In women, “1,25(OH)2D3 stimulated progesterone production by 13%, estradiol production by 9%, and estrone production by 21%”. This substance is found to promote the transportation of calcium to the placenta as well as improves the development of the uterus and placental tissues, which betters the reception and implantation of sperm should a woman get pregnant.

If there is one conclusion taken from this as well as older research, is that the more exposure to sun light results in higher rates of human reproduction, and less sun light causes the opposite effect. “In northern countries, where a strong seasonal contrast in luminosity exists, the conception rate is decreased during the dark winter months, whereas a peak in conception rate during summer leading to a maximum in birth rate in spring has been observed.” These conclusions can be explained by many environmental factors, including vitamin D deficiency. “The seasonal variation of vitamin D levels, might influence several pathways including altered endometrial development and altered oocyte development,” reads the study. The findings emphasize how there is evidence that vitamin D does affect female reproduction including cases where in-vitro fertilization is used as well as cases of women with polycystic ovary syndrome (PCOS).

The researchers’ closing remarks encourage further research about women and men infertility levels and the role that vitamin D plays as a supportive element to improve the human immune system as well as the to promote more fertility in women and men. “ Given the high prevalence of infertility as well as vitamin D insufficiency in otherwise healthy young women 70 and men 136 and the possible role of vitamin D in human reproduction, research might lead to new therapeutic approaches such as vitamin D supplementation in the treatment of female and male reproductive disorders.”