Selenium: Benefits for Fertility

Selenium: Benefits for Fertility

There was once a time when scientists believed that selenium was dangerous to human health. In recent decades, however, we’ve learned just how important selenium really is for many different biological processes. Of these, fertility is probably one of the most fascinating - and important.

So what made experts change their minds, and what are the benefits of selenium to reproduction?

What is Selenium?

Selenium is a mineral, but one that the human body only needs in very small amounts. As a result of this it is typically referred to as a “trace mineral”.

Selenium is surprisingly rare in nature, and isn’t found uniformly around the earth. Environmental factors can result in significant variation in the selenium content of soil - and hence the foods we eat.

Some areas of China, for example, have so much selenium in the soil that it has resulted in cases of toxicity. This explains why selenium was once considered as dangerous as lead when found in the environment.

At the other end of the scale, however, some parts of the world are so deficient in selenium that certain health-related health conditions are common. So common, indeed, that the conditions themselves have been named after the areas affected.

The key message here is that when it comes to selenium both a deficiency and an overdose can be equally dangerous. The key is getting just the right amount.

What Does Selenium Actually Do?

Possibly the best-known health benefit of selenium is in supporting the immune system. It seems that selenium acts rather like vitamin E, offering antioxidant benefits.

Selenium can not only help to keep beneficial cells safe from free radical damage, but can also help to attack and destroy less welcome cells. Some studies have even shown that this effect can be so potent as to reduce the incidence of some cancers when levels are sufficient.

Repeated studies have suggested that this same property is also central to selenium’s effect on fertility.

Benefits of Selenium for Male Fertility

Selenium is intricately linked to male reproductive health. While the majority of selenium in the body is found in the skeletal muscles, this trace mineral is found in the greatest density in the kidney, the liver and - you guessed it - the testes. It should therefore come as no surprise as to how important it really is for reproductive health.

Sperm Quality

Studies have shown that infertile men often suffer from unsuitable selenium levels. Again, these may be either too high or too low. Some studies have even identified the “sweet spot” for ensuring sperm mobility and overall health.

Convincing evidence comes from a study in which men were invited to add 75g of walnuts per day to their standard diet. Like other nuts, walnuts are a good source of natural selenium. The results showed that general reproductive health increased considerably when compared with a control group. The researchers concluded that “walnuts added to a Western-style diet improved sperm vitality, motility and morphology”. 

Sperm Count

It’s not just overall sperm health that selenium seems to impact, but even the actual sperm count itself. In a study of 125 couples suffering from infertility, it was noted that men whose selenium levels fell outside the “Goldielocks zone” tended to have a significantly reduced sperm count.

Supports Traditional Fertility Treatments

Medical professionals use a wide variety of treatments to help couples who struggle to conceive. Even here, however, there are cases where additional selenium can be beneficial.

One wide-ranging study looked at the effects of many different dietary antioxidants on fertility. This list included selenium, together with zinc, vitamin E and folic acid. The results showed an astonishing improvement in success rate of 4.85 times when comparing a diet rich in antioxidants versus a control group.

Of course, selenium isn’t the only option here - a diet rich in plant materials also contains plenty of antioxidants. However it does further expand on the findings that supplementing with extra selenium may be beneficial for men seeking to start a family. 

Benefits of Selenium for Female Fertility

When it comes to selenium for fertility, men are most commonly studied. However, there is still a surprising amount of evidence that selenium may also benefit women seeking to conceive.

In terms of female reproductive health the greatest impact seems to be less about the ability to conceive and more about gestational health. Here are some of the more interesting discoveries...

Full-Term Pregnancy

Repeated studies have indicated a relationship between low selenium levels and the risk of miscarriage. One study compared blood samples between women who suffered from miscarriage versus those who reached their full term. The scientists reported that while it is normal to see a small drop in selenium during the first trimester, those women who miscarried typically experienced “a further highly significant decrease” which directly correlated with the end result.

However, this effect seems to go wider. It’s not just women unfortunate enough to be affected by a single incident. Additional studies have been carried out on women suffering from repeated miscarriages over an extended period of time. Hair samples were analysed for micro-nutrient content, with the experts concluding that “there was evidence of selenium deficiency in women with recurrent miscarriages compared with a control group of women”.


According to the NHS, pre-eclampsia affects up to 6% of pregnant women. It is characterised by high blood pressure, which often makes itself felt in the form of swollen limbs, headaches and interrupted vision. There is currently no known cure apart from inducing an early birth.

An increasing body of research suggests that free radicals have a major part to play in pre-eclampsia. Furthermore, studies have noted that in cases of pre-eclampsia, blood found in the umbilical cord is typically much lower in selenium when compared to normal pregnancies. Unsurprisingly, therefore, there are those who suggest that an appropriate selenium intake before and during pregnancy may help to reduce the chances of suffering.

Birth Weight

Selenium has been implicated in the birth weights of babies. One detailed meta-analysis pooled the results of thousands of pregnancies, looking at how nutrients impact infant health. Their findings demonstrated that a low selenium level “in the early stage of pregnancy” has been “proved to be a reliable predictor of low birth weight of a newborn.” 

How Much Selenium Should I Consume?

The scientific evidence to date is quite convincing: selenium plays an important role in fertility and reproduction. But how much do you really need?

As mentioned, selenium can be seen as a “Goldielocks” nutrient, where levels either too low or too high can both cause issues. Indeed, one scientific study looking at healthy levels in the body claimed that “there is a relatively narrow window between selenium deficiency and toxicity”.

The NHS currently recommends the following intake:

  • 0.075mg a day for men (19 to 64 years)
  • 0.06mg a day for women (19 to 64 years)

Many doctors advise that it is easy to meet these levels by the consumption of a varied diet, rich in whole foods. Some of the best foods for selenium include Brazil nuts and many meats such as fish and beef.

At the same time, while selenium is only required by the body in small amounts, foods can vary based on where they are grown. As a result, some men and women struggling with infertility opt to take a selenium supplement to ensure a reliable intake.

Perhaps that’s why one large-scale study concluded that “supplementation in the case of selenium deficiencies in the procreation period of both women and men is of utmost significance”.


It seems that selenium really is important for fertility, but this isn’t just a case of taking as much selenium as possible. This could have quite the opposite effect of that intended. Instead, if you’re thinking of taking a selenium supplement for reproductive health you’d be well-advised to seek guidance from your doctor. They will be able to carry out tests to assess your selenium levels, and can propose a suitable course of action to remedy any issues.

Lastly, while we hope this guide has proved entertaining and informative, we would strongly encourage you to seek advice from your doctor before making any changes to your diet or lifestyle when it comes to fertility, conception and pregnancy.