Selenium’s and zinc’s essential role in fertility and a healthy pregnancy

Involuntary childlessness has become increasingly common. Many women find themselves in a race against time, and their biological clock keeps ticking louder and louder. Fertility therapies, miscarriages, preeclampsia, and other complications during pregnancy contribute to the physical and emotional burden. In a new Australian study that is published in Nutrients, the authors write about selenium and zinc and how these nutrients play an important role in fertility and a healthy pregnancy. They also address the problems with widespread selenium deficiency and point out that environmental toxins like mercury deplete levels of vital selenium-containing proteins in the body. The scientists point to supplements for fighting deficiencies, just like folic acid and iron are routinely recommended to pregnant women. It pays off to choose selenium yeast with multiple organic selenium compounds and organic zinc to help improve the bioavailability and utilization of the nutrients.

Infertility – which is defined as a lack of pregnancy after 12 months of trying to conceive – affects millions of couples worldwide. In Denmark, around one in seven couples suffers from infertility. There can be a number of underlying causes such as poor sperm quality, poor nutrition, stress, smoking, high maternal age, obesity and polycystic ovary syndrome (PCOS). Also, heavy metals like mercury, cadmium, lead and other environmental toxins may disrupt the hormone balance.
Selenium, zinc, and copper are known to have great importance for sperm cell quality and male fertility in general. However, science does not know much about these trace elements in terms of their importance for fertilization of the egg and for the early stages of pregnancy.
The aim of the new Australian study was to study the relation between plasma concentrations of selenium, zinc, and copper and the time it took for the women to become pregnant. It turned out that lack of selenium and zinc, not copper, made it more difficult to conceive. Other studies have shown that lack of selenium and zinc may also result in complications later on in the pregnancy and may even affect the health and weight of the baby.

The Australian study

Based on the international cohort study called Screening for Pregnancy Endpoints (SCOPE), the researchers studied 1,164 women from Adelaide in Australia. All were first-time pregnancies in week 14-16 and one-child only. The midwives collected information about demography, smoking, family relations, medical and gynecological history, diet, supplement use, BMI, blood pressure and waist circumference. Women who were unaware of their term, had diabetes, or were at risk of preeclampsia, miscarriage or preterm delivery were excluded from the study, leaving the total number of participants at 1,060. Based on the pregnant women’s self-reported intake of food and beverages during the month prior to conception, the scientists calculated intake levels of selenium, copper, and zinc. The participants also reported their use of supplements, and how often they had intercourse. Also, the researchers took blood samples to assess levels of selenium, zinc, and copper in the second pregnancy trimester.
894 (84.3%) of the 1,060 women took less than 12 months to become pregnant, and for 166 women (15.7%), it took more than 12 months. The study showed that low levels of selenium and zinc were associated with delayed pregnancy. Low selenium concentrations therefore increased by 46% the risk of the pregnancy occurring after 12 months.
According to a larger study from the cohort trial, which included women with involuntary infertility, selenium deficiency was associated with a 60% increased risk of childlessness. Because selenium and zinc deficiencies were widespread among the pregnant participants, the scientists found the study results to be highly relevant and believe this is something that deserves a lot more focus, both before and during the pregnancy. They also point to the fact that many pregnancy supplements do not even contain selenium.

Selenium sources and widespread deficiency

Selenium is mainly found in fish, shellfish, organ meat, eggs, dairy products, Brazil nuts, and green vegetables. European crops are generally low in selenium, and an estimated 20 percent of Danes get less selenium than the officially recommendation (the reference intake level is 55 micrograms).
Many experts recommend getting 100 micrograms every day. This is the dosage that it takes to saturate selenoprotein P, a selenoprotein that is used as a gauge for the body’s selenium status.
Although fish and shellfish are generally regarded as good sources, it is not possible to saturate selenoprotein P even if you eat seafood five days per week, according to a Danish study conducted with scientists from the Danish Cancer Society.

Selenium’s many functions in fertility and its importance for a healthy pregnancy

Selenium supports around 25-30 different selenium-dependent enzymes (selenoproteins) that help control our energy turnover, metabolism, and DNA synthesis. The selenoproteins also serve as powerful antioxidants that protect cells against oxidative stress caused by free radicals. Selenium is important for follicle growth and follicle maturation. Science has observed that women with unaccountable infertility have lower selenium concentrations in the extrafollicular fluid that nourishes the eggs.
Daily supplementation with 100 micrograms of organic selenium yeast during pregnancy from the first trimester until delivery can reduce the risk of a ruptured fetal membrane by over 30 percent, according to a placebo-controlled study that is published in Journal of Obstetrics and Gynaecology. Also, pregnant women who take selenium yeast have a lower risk of preeclampsia, which is the leading cause of preterm delivery. Preeclampsia may even turn into potentially life-threatening eclampsia.
A team of international scientists, including Danish researchers, have carried out a large study that has found a possible link between maternal DNA, selenium deficiency, and preterm delivery. It appears that selenium has a constructive and protective role during pregnancy, and the scientists refer to circulatory effects in the placenta and that selenium serves as a powerful antioxidant and counteracts inflammation.
Also, selenium can neutralize heavy metals like mercury by reacting with it to form an inert compound called mercury selenide, which the body can excrete. However, once selenium has been sequestered by mercury, it is no longer able to support the different selenoproteins that are important for fertility and pregnancy. Therefore, mercury poisoning, which is quite common, increases your need for selenium.

Zinc’s importance for fertility and for a healthy pregnancy

Zinc is a co-factor in well over 1,000 enzyme processes and it is bound to around 10 percent of the proteins in our body. Zinc is essential for a host of different processes that control fertility, growth, metabolism, and many other things. Zinc is also a powerful antioxidant that protects cells against oxidative stress.
It goes without saying that maternal zinc levels in the blood are highly important just before the actual conception, during the conception, and during the pregnancy. Animal studies show that zinc deficiency may result in abnormal development of the ovaries, follicles, and eggs.
According to the new Australian study, women with the lowest zinc levels in their blood took 14 days longer to become pregnant. Although the difference is not that significant, the scientists do stress the importance of getting enough dietary zinc to support fertility and pregnancy.
Around half the pregnant women in the study got zinc from their daily multivitamins. Other studies show that low blood levels of zinc are linked to low birth weight and preterm delivery. Zinc is also an important mineral for breastfeeding, and a woman loses twice as much zinc during the period where she breastfeeds.

Zinc sources and an explanation to why deficiencies are so common

Zinc is mainly found in meat, shellfish, dairy products, nuts, kernels, and beans. Animal sources of zinc have better absorption than plant sources. The absorption of zinc is impaired by sugar and birth control pills plus inorganic iron supplements. Pregnant women who are advised to take iron should make sure to choose organic iron supplements. Although severe zinc deficiency is rare in our part of the world, moderate and minor deficiencies are rather common. Pregnant women should always make sure to get enough of this vital nutrient.

Choose organic zinc supplements that the body can absorb and utilize

To begin with, make sure to get enough dietary zinc from good sources. Many available supplements contain inorganic forms like zinc sulfate or zinc oxide that are not absorbed all that well. Organic zinc sources like zinc gluconate and zinc acetate are much more bioavailable, so make sure to study the label before making your purchase.

References

Jessica A. Grieg et al. Maternal Selenium, Copper and Zinc Concentrations in Early Pregnancy and association with Fertility. Nutrients 2019

Aparna Shreenath. Selenium Deficiency. StatPearls. May 6, 2019

Lutz Shomburg. Dietary Selenium and Human Health. Nutrients 2017

Lasse Foghsgaard. Mysteriet om for tidlig fødsel er kommet nærmere en opklaring. Politiken 07- 09-2017

Hilten T Mistry et al. Selenium in reproductive health. Journal of Obstetrics and Gynaecology. 2011

Fatemeh Tara et al. Selenium supplementation and premature (pre-labor) rupture of membranes: a randomized double-blind placebo-controlled trial. Journal of Obstetrics and Gynaecology. 2010

Jones GD et al. Selenium deficiency risk predicted to increase under future climate change. Proceedings of the National Academy of Sciences 2017
Editorial team. Selenium deficiency promoted by climate change. ETHzüric 2017

Nicolas V.C. Ralston, Laurs J. Raymund. Mercury’s neurotoxicity is characterized by its disruption of selenium biochemistry. Elsevier

Bo Jønsson et al. Zinc supplementation during pregnancy: a double blond randomized controlled trial. Acta Obstet. Gynecol. Scand. 1996