Vitamin D plays many roles in the human body, and some theorize that a deficiency may influence infertility in men. 


By Natalist advisors Dr. Andrew Sun and Lauren Manaker, RD

Vitamin D is a hot topic these days. It is a fat-soluble vitamin that gets converted into a hormone in the body. It is found in some foods and can also be converted through skin from UV light from the sun. 

Vitamin D and male fertility

Vitamin D plays many roles in the human body, and some theorize that a deficiency may influence infertility. In general, the recommended dietary allowance of vitamin D for adult men under the age of 70 years old is 600 IU/day, although some argue it should be higher due to the prevalence of vitamin D deficiency in the United States. Some say that more than 40 percent of the U.S. population is vitamin D deficient. One contributing factor to this issue is the modern lifestyle most of us live, with limited skin exposure to sunlight and, thus, limited exposure to the UV light. 

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The role of vitamin D in hormone production and sperm creation has been investigated in both animals and humans. Experimental studies support a beneficial effect of vitamin D on male fertility by playing a role in hormone production and by improving sperm parameters.  

Clinical studies in humans regarding vitamin D and fertility have been controversial and more research is needed. Some studies have demonstrated a positive effect of vitamin D intake on semen quality and motility according to a literature review.  Conversely, a study conducted with men specifically undergoing IVF demonstrated no correlation between vitamin D status and any fertility variables (motility, count, or morphology).

In regard to the studies that suggest the positive effect of vitamin D on male fertility, it is important to note that vitamin D does not appear to exert an important role in human fertility in the absence of deficiency. In other words, if a man already has adequate vitamin D levels, supplementation will not likely provide a benefit. 

Dietary and supplemental forms of vitamin D

Determining whether there is a true vitamin D deficiency requires a blood test. It is relatively inexpensive and easily accessible. If a man is diagnosed with a vitamin D deficiency, in general, it is a good idea to ensure adequate vitamin D intake to replenish levels for many reasons beyond fertility. If supplementation is being considered, the medical community generally recommends taking the D3 form (not the D2 form). This is because there is some evidence that indicates vitamin D3 is more efficacious at raising serum 25-hydroxyvitamin D concentrations than is vitamin D2. 

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Some dietary sources of vitamin D include:

  • Fatty fish like salmon and tuna
  • Egg yolks
  • Dairy drinks and dairy-alternative drinks fortified with vitamin D
  • Certain mushrooms
  • Vitamin D-fortified orange juice and yogurt

Additionally, direct exposure of skin to sunlight allows vitamin D to naturally be converted in the body.

This is an excerpt from the Guide to Male Fertility.