Male Infertility: Vitamin D Can Improve Pregnancy Success

Consider this scenario: You and your partner are ready to start a family. However, after a year of failed attempts to conceive, you decide to visit a fertility specialist to determine what is preventing your family from growing. The tests come back. You or your partner are diagnosed as infertile.

Unfortunately, this is the reality that over 5 million people face within the United States alone. In addition, according to a new study, male infertility is on the rise. Researchers from this study found sperm counts have declined by nearly 60% over the last 40 years among European, North American and Australian men.

Kez Emeny, a clinical embryologist at a fertility clinic based in Southern California, stated:

“Out of the ~400 cycles we perform per year, 21-22% of these cycles are performed due to male factor. This includes male patients with either [one or a combination of] all of the following: low [sperm] count, low motility, low morphology, medical condition, genetic/chromosomal abnormality or surgical sterilization (patients who have had a vasectomy and have to undergo a surgical sperm retrieval).”

Vitamin D has developed a reputation for benefiting sexual health; however, is there any merit behind the puns? It turns out, there is.  Research suggests vitamin D status indeed plays an important role in reproductive health. In fact, vitamin D status has been linked with sexual function,  testosterone levels and fertility. In addition, studies have found vitamin D deficiency is more prevalent among men with low semen production, quality and motility, along with lower inhibin B levels.

Kez Emeny explained the relevance of inhibin B status on male fertility:

“Inhibin B levels reflect testicular function and Sertoli cell function. Inhibin B levels are reduced in men with infertility problems compared with fertile men. Studies show that inhibin B levels are a more sensitive marker of male factor infertility than other hormones.”

In an effort to determine whether vitamin D supplementation may improve semen quality and hormonal imbalances among infertile men, researchers from Denmark recently conducted a triple blinded, randomized controlled trial. Men were included in the study if they were part of a couple diagnosed with infertility due to impaired semen quality, had vitamin D levels below 20 ng/ml (50 nmol/l) and did not have any serious secondary diseases.

A total of 307 individuals participated in this study. The participants provided two semen samples for analysis, as well as received a blood draw at baseline. The men were randomly assigned to two groups:

  • Group one received a single dose of 300,000 IU vitamin D3 along with a daily dose of 1,400 IU vitamin D3 and 500 mg of calcium for 150 days.
  • Group two received a single oil based placebo, followed by a placebo pill for 150 days.

The participants received a call from their nurse to assess any complications about one month after beginning supplementation. After 90 days, the men had a follow up appointment where they received another blood draw and were given supplements for the remaining 60 days of the study. Between 140 and 150 days into the study, the participants provided two additional semen samples for analysis.

Here is what the researchers found:

  • Average baseline vitamin D status was 14 ng/ml (35 nmol/l).
  • The vitamin D group experienced a 17.2 ng/ml (43 nmol/l) increase in 25(OH)D compared to the 2 ng/ml increase in the placebo group (p < 0.001).
  • The vitamin D group experienced a 30% increase in 1,25(OH)D levels after 5 months (p < 0.01); whereas the placebo group experienced an 8% decrease in 1,25(OH)D by the end of the study (p < 0.05).
  • There were no cases of vitamin D toxicity.
  • Vitamin D supplementation did not impact semen quality (p = 0.108 ).
  • A total of 7.3% of the couples in the vitamin D group achieved spontaneous pregnancy (without assistance from physician); whereas only 2.4% became pregnant in the placebo group.
  • In a subgroup analysis of men with low sperm count (oligozoospermia), the chances of a live birth increased to 35.6% in the vitamin D group, compared to 18.3% in the placebo group (p = 0.04).
  • Serum inhibin B levels were 49 pg/ml higher among the vitamin D group compared to the placebo group (p = 0.021).
  • Serum inhibin B/FSH ratio changes were positively associated with changes in vitamin D status over the 5-month period (p = 0.038).
  • Sperm count tended to be higher in the vitamin D group compared to the placebo group, though this did not reach significance (p = 0.07).

The researchers concluded,

“High dose vitamin D supplementation did not improve semen quality in vitamin D insufficient infertile men. The positive impact of vitamin D supplementation on live birth rate and serum inhibin B in oligozoosperic and vitamin D deficient men may be of clinical importance and warrant verification by others.”

Founder and Medical Director of the Vitamin D Council, Dr. John Cannell, shared his experience when treating one of his psychiatric patients. He stated,

“Several years ago I was treating a woman for bipolar disorder. After a few visits I learned that she and her husband were barren. They had been to infertility clinics where they spent a small fortune. I ordered a 25 (OH)D on both her and her husband; she was 22 ng/ml while he was 14 ng/ml.

I put them both on 10,000 IU (250 mcg)/day. She was pregnant 9 months later and delivered a healthy child. They thought I was a miracle worker. (Yes, I advised they give the child 25 mcg/every 25 lbs/day; Low and behold she became pregnant again and had an uneventful delivery.

Of course, this vignette, while suggestive, does not prove vitamin D helps fertility. If you and your partner are infertile, order a in-home test kit and find out what your vitamin D level is.”

Due to the safety of vitamin D supplementation, along with its proven impact on reproductive health among both men and women, the Vitamin D Council recommends supplementing with 5,000-10,000 IU (125- 250 mcg) vitamin D3 per day in order to maintain optimal vitamin D status (40-60 ng/ml; 100-150 nmol/l).

Has vitamin D helped your reproductive health? Please consider sharing your story with the Vitamin D Council team at to help us help others who struggle with infertility issues.


Sturges, M. & Cannell, JJ. Male infertility: How can vitamin D help? The Vitamin D Council Blog & Newsletter, 12/2017.


Jensen, M., MD. et al. Effects of vitamin D supplementation on semen quality, reproductive hormones and live birth rate: a randomized clinical trial. The Journal of Clinical Endocrinology & Metabolism,2017.

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