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, and you or your partner are diagnosed with infertility.
Unfortunately, this is the reality that over 5 million people face within the United States alone. In addition, male infertility is on the rise. In fact, researchers recently discovered sperm counts have declined by nearly 60% over the last 40 years among European, North American and Australian men.
Vitamin D and reproductive health
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.”
RCT evaluates relationship between vitamin D and male infertility
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 who met the following criteria joined the sudy:
- Part of a couple diagnosed with infertility due to impaired semen quality
- Vitamin D levels below 20 ng/ml (50 nmol/l)
- No history of 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. Participants 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 received another blood draw along with 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.
What did the researchers find?
- Average baseline vitamin D status was 14 ng/ml (35 nmol/l).
- The vitamin D group experienced a 30% increase in active vitamin D levels after 5 months; whereas the placebo group experienced an 8% decrease in 1,25(OH)D by the end of the study.
- Vitamin D supplementation did not impact semen quality.
- 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, the chances of a live birth increased to 35.6% in the vitamin D group, compared to 18.3% in the placebo group.
- Serum inhibin B levels were 49 pg/ml higher among the vitamin D group compared to the placebo group.
- Serum inhibin B/FSH ratio changes were positively associated with changes in vitamin D status over the 5-month period.
- Sperm count tended to be higher in the vitamin D group compared to the placebo group, though this did not reach statistical significance.
Final thoughts
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).
Source
Citation