Why Vitamin B12 is Important for Male Fertility

It is very important not to underestimate the importance of nutrients in supporting fertility. B12 is one such vitamin that can influence male reproductive health. A member of the B vitamin group, B12 is a large, complex molecule responsible for a range of functions within the body. Specifically, B12 is associated with red cell production, higher brain functions, cellular metabolism, and DNA maturation and duplication. The relationship between vitamin B12 and DNA production has important implications for male fertility, especially in association with sperm health and development.

Vitamin B12 and Sperm Count

male infertilitySince the 1970s scientists have been investigating the effects of B12 supplementation on sperm count. It’s believed that deficiencies in this vitamin lead to genetic damage of the sperm cells, causing infertility. Modern diets are typically saturated with highly processed foods and consequently B12 deficiencies are not uncommon.

In a study by Sanler and Faragher vitamin B12 injections have been shown to increase fertility in men with low sperm counts. In this study, 27% of men with abnormal sperm counts (below 20 million per millilitre) showed a significant increase in sperm count (more than 100 million per millilitre) after a daily dose of 1,000 mcg of vitamin B121.

Several years later, Japanese scientists attempted to replicate these findings. Using mecobalamin, a form of vitamin B12, Kumamoto and colleagues conducted a double-blind comparative trial2. They found that sperm counts slightly increased in association with mecobalamin supplementation. However, this trial was only conducted over a period of 12 weeks and patients’ mean pre-treatment sperm counts fluctuated; thus no conclusive results could be drawn from this research.

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In another Japanese study, researchers administered 1,500 mcg per day of methylcobalamin orally for between two and thirteen months. Improved sperm counts were observed in 60% of men receiving the supplement. The longer the period of supplementation, the more stable the sperm counts.

Most studies show that men with B12 deficiencies and low sperm counts can significantly benefit from large-dose supplementation. Men not deficient in B12 have also been reported to benefit from additional B12. One theory is that with higher levels of B12 the body is able to increase metabolism and provide more resources to manufacture sperm. Another theory is that increased red blood cell production may improve oxygenation and overall reproductive health. Although more research is necessary, mega-dosing vitamin B12 is considered relatively safe.

Vitamin B12 and Erectile Dysfunction

There are many physical factors that contribute to erectile dysfunction. Insufficient supply of B12 can damage the nerves within the penis. Left untreated, the damage will prevent the development and maintenance of an erection. This can lead to fertility problems by reducing the ability to sustain intercourse and subsequent ejaculation. It’s important if men are having erectile dysfunction symptoms that they seek medical attention and test vitamin B12 levels. Not only will this vitamin help to protect nerves within the penis, it will also support healthy circulation to promote strong erections.

vitamin b12-rich foodsSources of vitamin B12

Some of the best natural sources of B12 include fish, shellfish, beef, fortified cereals and soy products, low-fat dairy, cheese, poultry, and eggs.

There are plenty of multivitamins include the B-group vitamin complex that can help ensure that the body has sufficient access to these important compounds.

 Male fertility supplements

Whilst a balanced diet is essential, supplements are able to deliver the required nutrients in the minimum quantities more cost-effectively and efficiently than any regular diet. 

A supplement is recommended for two groups of men:  

  • Men already planning for a child and
  • men, who have been diagnosed with suboptimal semen analysis readings.

Both groups will benefit from supplementing micronutrients to ensure they can deliver high-quality semen.

Male fertility supplements are

  • without side effects
  • able to increase sperm motility by up to 23%,
  • able to increase ejaculate volume by up to 33%
  • able to increase sperm count by up to 215%3
  • relatively inexpensive
  • effective after three to six months

The European market is saturated with many male fertility supplements, which differ significantly in terms of nutrients and price. Menfertility.org has diligently compared 12 of them in terms of value for money and nutrients provided.


Click the button to read the comparison of male fertility supplements


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  1. Sandler B, Faragher B. Treatment of oligospermia with vitamin B12. Infertility. 1984. 7:133–8
  2. Kumamoto Y, Maruta H, Ishigami J, Kamidono S, Orikasa S, Kimura M, Yamanaka H, Kurihara H, Koiso K, Okada K. Clinical efficacy of mecobalamin in the treatment of oligozoospermia-results of double-blind comparative clinical study. Hinyokika Kiyo. 1988. 34(6): 1109-32
  3. Imhof M, Lackner J, Lipovac M, Chedraui P, Riedl C. Improvement of sperm quality after micronutrient supplementation. e-SPEN Journal. 2012. 7(1): e50-e53
3 replies
  1. Michael Harrington
    Michael Harrington says:

    Vitamin B5 is awesome for men’s health too. Using a penis health creme containing this important vitamin will greatly improve the overall function of the penis. All guys should start using one of these cremes. Cheers!

  2. Chris
    Chris says:

    For those who are B12 deficient, I recently heard about a new oral prescription alternative to the injections called Eligen B12. I recently read that it works even if you don’t have intrinsic factor (so even if you don’t have normal gut absorption), which would mean no more shots. Apparently it came out a month or two ago. Has anyone tried it??


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