Topical media speaks about the recent findings of male sperm counts dropping in westernized countries to half of what they were a decade ago. The implication is the reduced fertility rates which are more important as they too have been dropping. What does this mean? People who are trying to conceive are less successful. Is vitamin D3 connected?

In ancient times fertility rituals were common in the late summer and early fall when vitamin D3 blood levels would be at their peaks. This meant that births were in spring and early summer when food was at its peak availability and weather the least dangerous. This makes sense, as like hibernating we would want to time reproduction for an ideal period. This seasonality of birth of animals and humans is well established.1

In the last 50 years, sun exposure and vitamin D3 levels have been dropping as well. While all the rage is about sperm counts, as important, if not more important, is the quality of the sperm.

This is where vitamin D3 and vitamin D receptors come in, as the receptors are found throughout the male and female reproductive system. Though not definitive, it gives further support that vitamin D may regulate the reproductive system. Like I have written before the body doesn’t waste its resources producing things like this receptor if they aren’t important.

How does vitamin D3 levels correlate with fertility? First, I am not implying the sperm count drop is from a reduction in vitamin D3 levels as no studies show that yet, but then again, all the vitamin D studies are at levels much below optimal and if done at optimal levels the results might be much different. If nothing else, the body will be healthier which can only improve reproductive success. Also, beyond sperm count, more important is sperm quality. It makes no difference if a man has one or a billion sperm if they all are defective. This is where vitamin D3 makes a significant effect on fertility and reproductive success.

A scientific article2 and then a blog post3 both published in 2015 discuss this and further support the correlation between vitamin D, sperm quality and fertility though not sperm count. Researchers found even when considering an extremely low blood level of vitamin D of 30ng/ml as normal and the cut off between the two groups, study results showed a significant difference and improvement in conception for the males with higher vitamin D blood levels. Another study in 2017 showed improved fertility with higher vitamin D3 blood levels but no difference in sperm counts.4 Like all things, it is complex and needs more study, most importantly with optimal levels. What is amazing is that even at such low levels there is a difference, so imagine what is possible with optimal dosing and higher D3 blood levels.

  1. Rodjansky N,Brzezinski A, Schnker JG.. Seasonality in human reproduction an update. Hum Reprod. 1992 Jul;7(6):735-45.
  2. Tartagni M, Matteo M, Baldini D, et al. Males with low serum levels of vitamin d have lower pregnancy rates when ovulation induction and timed intercourse are used as a treatment for infertile couples: results from a pilot study. Reproductive Biology and Endocrinology. 2015;13:127.
  3. Sturges M, Cannell JJ. Does low vitamin D status reduce male fertility? The vitamin D Council Blog and Newsletter, December 8, 2015.
  4. Blomberg JM, Lawaetz JG, Peterson JH, et al. Effects of vitamin D supplementation on seman quality, reproductive hormones and live birth rates: A randomized clinical trial. Clin Endocrinol Metab. 2018 Mar 1;103(3):870-881.


*The information posted above is for educational purposes only. Always check with your doctor before initiating any changes in your medical treatment. If you do not, then The Two-Minute Health Fact, Dr. Judson Somerville, nor The Optimal Dose is responsible!


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