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Does Homocysteine Impact Reproductive Health for Men and Women?


The foundation of reproductive health is systemic health. A metabolic byproduct, called homocysteine, is a good example. This amino acid has been known to affect multiple aspects of our systemic health, but studies have found that homocysteine may also impact both male and female reproductive health.


What is homocysteine?

Homocysteine is a type of amino acids. It’s a byproduct of two interconnected biochemical cycles that generates methionine, an essential amino acid, and cysteine, another amino acid. Both methionine and cysteine are building blocks of proteins that our bodies need, but homocysteine is not. 

Normally, homocysteine levels in the blood are kept quite low. Using B vitamins, the body quickly breaks down homocysteine as it’s generated from methionine, and “recycles” it back into methionine and cysteine. This circular process is called methylation.


What is a normal homocysteine level?

The normal range of homocysteine levels can vary slightly, based on which lab runs the test. However, in general, homocysteine level below 15 mcmol/L is considered healthy.


What causes high homocysteine levels?

However, some people have high levels of homocysteine circulating in the blood. There are several risk factors for elevated homocysteine levels.         

  • Low intake of B vitamins: The body needs Vitamin B6, Vitamin B12 and Folate in order to break down homocysteine. Studies have shown that inadequate intake of these B vitamins (which is shockingly common) can lead to high homocysteine levels – and this is partly why some doctors recommend men to also take prenatal vitamins with folate, when they are trying for a baby.
  • Genetics and hereditary conditions: People with common mutations of the MTHFR gene can have difficulty breaking down homocysteine. There are several other heritable conditions that can affect your homocysteine levels.
  • Health conditions and medications: Certain health conditions like heart disease and kidney disease are risk factors for high homocysteine levels. Medications, including metformin and methotrexate can also lead to high levels.
  • Low thyroid hormone levels: Studies have found that people with low TSH (thyroid-stimulating hormone) levels may be more likely to have high homocysteine levels.

Age and gender also affect the likelihood of having too much homocysteine. An analysis of over 7,000 people found that men are far more likely to have high homocysteine levels than women (up to 9 times). With respect to age, the prevalence of high homocysteine levels followed a U-curve, with both men and women in their 30s, 40s and 50s having the lowest prevalence and those over 60 seeing a steep increase in prevalence.



Connection between homocysteine and reproductive health

Having too much homocysteine is a known risk factor for systemic health issues. The most known association is in the cardiovascular realm, as homocysteine can damage the walls of blood vessels, but doctors believe that there are other systemic health impacts.

In reproductive health, doctors have noticed that normal (i.e., low) homocysteine levels may be associated with normal reproductive functions in both men and women. Overall, studies have suggested a link between healthy homocysteine levels and embryo quality, chances of conception, as well as the maintenance of a healthy pregnancy.

Results on specific outcomes are mixed, but scientists have proposed several mechanisms that may be at play.


1. Homocysteine and sperm quality

Men are more likely to have high homocysteine levels than women, so keeping your homocysteine levels healthy is particularly important for men. Studies have found that a healthy levels of homocysteine in both the blood and the seminal fluid may be associated with high sperm quality measured in sperm analysis – like sperm count, motility (how well the sperm swims) and morphology (sperm’s structural integrity).

Homocysteine is also known to increase oxidative stress, which has been linked to DNA damage in sperm. While sperm DNA is not a part of the conventional sperm analysis, it’s an important factor in male reproductive health, as the DNA from sperm form half of the embryo’s DNA. This may be partly why embryos from men with normal homocysteine levels tend to be healthier.


2. Homocysteine and ovulation

On the female side, a healthy, low homocysteine levels may be associated with several aspects of reproductive processes. For example, a study of 259 healthy women found that women with healthy homocysteine levels at the time of ovulation were about 25% more likely to ovulate regularly than those with elevated homocysteine levels.


3. Homocysteine and egg quality

Increased oxidative stress due to homocysteine may also affect egg quality. Several studies have looked at the relationship between egg quality and homocysteine levels in both the blood and the follicular fluid (the fluid that fills the ovarian follicles that contain developing eggs), and found that women with healthy homocysteine levels are more likely to have better egg quality.

Some studies have also found a weak connection between healthy homocysteine levels and genetic integrity of eggs, which, of course, can impact the resulting embryo’s quality and developmental potential.


4. Homocysteine and healthy pregnancy

Once a pregnancy is established, the mom’s homocysteine levels have been suggested as one of the many factors contributing to the health of the pregnancy. This may not be surprising, given the multiple ways too much homocysteine can impact systemic health.

For example, a study that looked at a birth cohort of over 7,500 in Canada found a statistically significant association between the mom’s homocysteine levels and multiple aspects of the health of the pregnancy. Even just 5 mcmol/L of increase in homocysteine levels were linked to a 63% increase in the overall risk of pregnancy complications in this study.


What to do to keep your homocysteine levels healthy

So, regardless of your sex, it may be important to keep your homocysteine levels nice and low, when trying to conceive. There are several things you can do to maintain a healthy homocysteine level.

  • Get a MTHFR gene test: The MTHFR gene mutations that reduce the efficiency of homocysteine breakdown are quite common. If in doubt, ask your doctor if you should take a MTHFR gene test. If you do have one of the mutations, taking prenatal vitamins with folate (an activated form of folic acid), rather than folic acid, can help.
  • Get plenty of B vitamins: With inadequate intake of Vitamin B6, Vitamin B12 and Folate, our bodies become inefficient at “detoxifying” homocysteine into methionine and cysteine. Make sure you are getting enough B vitamins through diet and/or from prenatal vitamins.
  • Don’t smoke, and don’t drink to excess: Both smoking and excessive alcohol consumption have been linked to higher likelihood of elevated homocysteine levels. Refraining from smoking and excessive drinking will also help with other aspects of reproductive health, so no reason not to try.
  • Keep your blood pressure in check: Healthy homocysteine levels and cardiovascular health appear to be in a virtuous cycle, meaning that they appear to affect each other. Keep your cardiovascular fitness by incorporating regular movements into your daily life and watching your sodium intake – and you will also be helping your body break down homocysteine.
  • Talk to your doctor and get a homocysteine blood test: Of course, the best course of action if you are concerned about possibly having high homocysteine levels, is to consult your doctor and get a blood test to measure your homocysteine levels. Depending on the result, your doctor can work with you to develop a plan of action.

The healthy habits you build around homocysteine during your preconception period will also be a foundation for your lifelong health. Please reach out if we can answer any questions about homocysteine and your reproductive health. We are with you.



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