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Vitamin B12 & Infertility

The connection between patients who are B12 deficient and infertility

The fact that our bodies require vitamin B12 to stay healthy has been accepted for a long time by all types of health organizations. It has also been well accepted that vitamin B12 plays a critical role in fetal development. For example, several studies show that low levels of vitamin B12 may increase the risk of Neural Tube Defects (NTD), a birth defect that affects the brain and spinal cord. But there seems to be some disagreement whether Vitamin B12 plays a role in infertility and in recurrent fetal loss. After reading a few papers on this subject, I would like to offer my opinion.

A common denominator among most papers that I read regarding the importance of vitamin B12 is something called Homocysteine (Hct). This substance is an essential type of amino acid obtained from the food that we eat every day. With the help of vitamin B12, vitamin B6, and folic acid (also called folate or vitamin B9) the body quickly breaks down homocysteine and changes it into other substances that it needs. High levels of homocysteine (Hyperhomocysteinemia) have been shown to be very damaging to the inside of the arteries – increasing the risk of heart attack, stroke, and other cardiovascular disorders.

The studies

For the past 2 decades or so, we have been seeing studies investigating the relationship between infertility and vitamin B12 deficiency. A study published in 2001 by the Journal of Reproductive Medicine concluded that:

“Raised levels of homocysteine may lead to fetal loss when vitamin B12 is deficient”.

The study continues to mention in their Conclusion that:

“A more prolonged deficiency results in infertility by causing changes in ovulation or development of the ovum or changes leading to defective implantation”.

Another study released in 2016 by the Current Hypertension Review looked at homocysteine, vitamin B12 and folic acid levels during all three trimesters in pregnant and preeclamptic women. The study concluded that:

vitamin B12 levels were lower in maternal blood of hypertensive pregnant women as compared to normotensive pregnant women”.

A more recent study, published by The American Journal of Clinical Nutrition concluded that:

“Women in the highest quartile of serum vitamin B12 (>701 pg/mL) had over 2 times the probability of live birth compared with women in the lowest quartile (<439 pg/mL)”.

Although the objective of this study was to evaluate the associations of serum folate and vitamin B-12 with ART outcomes, I strongly believe that the results of this study are applicable to couples who are trying to conceive naturally.

Deficiency Symptoms

Because vitamin B12 is required to make healthy red blood cells, white blood cells, and platelets, a common symptom of B12 deficiency is fatigue. When it comes to fertility, the following symptoms can also be observed:

Vitamin B12 Deficiency In Women:

If a woman gets pregnant while having low levels of vitamin B12, there is a higher risk of the pregnancy resulting in miscarriage.

The lack of B12 seems to interfere with the reproduction & adds to:

  • Impaired development of the egg

  • Abnormal ovulation

  • Difficulty in implanting the fertilized ovum in the uterine lining

  • Disruption in normal cell division

Vitamin B12 Deficiency in Men:

  • Vitamin B12 helps generate and mature the sperm

  • Premature ejaculation

  • Low motility of sperm

  • DNA damage in sperm cells

  • Low sperm count

  • Loss of libido


If you have been having difficulties conceiving and all the obvious tests are coming back negative, it might not be a bad idea to check the levels of vitamin B12 – especially if Folate (B9) has been taken as a supplement since it can hide some of the symptoms of B12 deficiency. I believe it is always a good idea to compare different but similar biomarkers to get a better picture of what could be going on. A homocysteine test may be used to check the level of this essential amino acid. As explained earlier, a lack of vitamin B12, B6, or folic acid will show an increase of homocysteine since these are the vitamins responsible for breaking down homocysteine.

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