During pregnancy, women need an increased intake of the trace element selenium. Low selenium intake and status in the pregnant mother will be reflected directly in poor selenium status in newborns [Filipowicz 2022].
Women living in regions with low selenium content in the soil and in the food most likely need a selenium supplement. A study conducted in selenium-poor central Poland has revealed that supplemental selenium in a dosage greater than 55 mcg/day can improve pregnant women’s selenium status [Filipowicz 2022].
In the Polish study, one-third of the mothers reported self-initiated additional selenium intake. For the most part, these women took a multi-vitamin and mineral supplement. The tablet added, on average, 42 mcg of selenium to their diets daily. Even so, 79% of these women had serum selenium concentrations below 70 mcg/L (selenium deficiency levels). Moreover, 22% had serum selenium concentrations below 45.9 mcg/L (severe selenium deficiency levels) [Filipowicz 2022].
Three Different Selenium Measures in Pregnant Women
The Polish researchers measured three different selenium biomarkers: total serum selenium concentration, serum selenoprotein P (SELENOP) level, and GPx3 activity [Filipowicz 2022].
- Relatively low SELENOP concentrations and GPX3 activity reflected the low total serum selenium status in the mothers.
- The insufficient selenium intake and selenium status were reflected in the newborns. All three of the biomarkers of selenium status were significantly lower in newborns than in the mothers.
- None of the three biomarkers of selenium status were significantly higher in the group of mothers who reported taking supplements than they were in the non-supplementing group. However, the sub-group of mothers who took supplements adding more than 55 mcg/day to their diets did show elevated SELENOP concentrations.
Selenium Intake Affects Mother and Child
During pregnancy, the pregnant woman transfers increasing quantities of selenium to the growing fetus. This transfer leads to ever more depletion of the pregnant woman’s selenium status. Then, the new mother’s selenium deficit may worsen during the period of lactation. The insufficient supply of selenium can have negative health effects on both the new mother and the infant child. Selenium supplementation is necessary to ward off the negative consequences of inadequate selenium supply [Schomburg 2021].
After giving birth, the new mother is vulnerable to postpartum thyroid disease. Postpartum thyroid disease is a not uncommon autoimmune disorder, in particular for women with positive thyroid autoantibodies. A 2007 randomized controlled trial conducted in Italy has shown that selenium supplementation during pregnancy and in the postpartum period – 200 mcg/day – prevented the development of postpartum thyroid disease and reduced the incidence of hypothyroidism [Negro 2007].
There is some limited clinical evidence for the hypothesis that severe selenium deficiency (serum levels below 45 mcg/L) can trigger the development of autoimmune disorders. The reasoning behind the hypothesis is that the immune system needs selenoproteins for immune cell differentiation between self-produced and non-self produced substances that induce an immune response. This differentiation is especially important during periods of demanding conditions such as pregnancy. It is likely that severe selenium deficiency can impair immune system responses and predispose to autoimmune disorders [Schomburg 2021].
Low Serum Selenium and Gestational Diabetes
In the Odense Child Cohort study, researchers observed that low serum selenium in pregnancy is significantly associated with gestational diabetes and with the birth of offspring large for gestational age. Assessing selenium status in pregnancy can identify females at high risk for gestational diabetes. These women may benefit from selenium supplementation [Demircan 2023].
Low Serum Selenium and Preeclampsia
In a series of studies, researchers have shown that supplementation with a selenium-enriched yeast preparation during pregnancy has the following significant beneficial effects in pregnant women with low selenium status:
- decease in risk of preeclampsia [Rayman 2014; Tara 2010 Jun]
- prevention of postpartum depression [Mokhber 2011]
- reduction of oxidative stress during pregnancy [Tara 2010]
- reduction of the risk of pregnancy-induced hypertension [Rayman 2015]
- reduction in the incidence of pre-labor rupture of membranes [Tara 2010 Jan]
Conclusion: Selenium Status Important in Pregnancy
Selenium supplementation should be strongly recommended for individuals with acute or chronic deficiency, including pregnant and lactating women. Serum selenium status below 70 mcg/L constitutes deficiency status.
Healthy individuals with sufficiently high baseline levels – serum levels above 100 mcg/L – most likely do not need selenium supplementation.
Early selenium supplementation can reduce the risk of dropping into the danger zone of severe selenium deficiency and immune system failure. Serum selenium status below 45 mcg/L constitutes severe selenium deficiency [Schomburg 2021].
Schomburg notes that the possible adverse effects of selenium supplementation are often exaggerated. This leads to a lack of attention to the more common health risks of selenium deficiency. Thus, safe preventive and adjuvant treatment options using selenium are neglected. This is especially true in pregnancy [Schomburg 2021].
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The information presented in this review article is not intended as medical advice. It should not be used as such.