During pregnancy, the unborn child needs different nutrients for proper development of its brain and nervous system. Even if the mother eats a balanced diet, it can be difficult to get enough selenium for a number of reasons. In a new Italian animal study that is published in Nutrients, scientists have looked closer at selenium’s role during pregnancy and lactation. They observed that even minor selenium deficiencies can have a negative effect on the offspring’s brain development and behavior. This study supports earlier human studies showing how vital it is for the mother to get plenty of selenium during pregnancy and breastfeeding.
Over the past thirty years, there has been increasing focus on the maternal diet’s impact on pregnancy and how the diet affects the child’s risk of developing chronic diseases later in life. There is particularly much focus on selenium, which is because the selenium content in agricultural soil in different parts of the world varies quite a lot. For instance, the selenium intake in countries like the United States and Japan is comparatively high, whereas it is a lot lower in European countries. In fact, the dietary selenium intake in Europe is often below the recommended level.
Selenium supports well over 25 different selenoproteins that are involved in the body’s energy turnover, metabolism, immune defense, fertility, and fetal development. Several selenoproteins serve as powerful antioxidants that protect cells and tissue against free radical damage and oxidative stress.
At the beginning of the new study, the scientists looked at four selenoproteins that are particularly relevant for the brain and nervous system:
- Selenoprotein P. Carries selenium to the neurons by way of the bloodstream.
- Glutathione peroxidase 1-6 (GPX 1-6). Antioxidant function.
- Thioredoxin reductase (TXNRD). Antioxidant function and energy turnover.
- Selenoprotein W. Antioxidant function.
More specifically, these selenoproteins are involved in a number of different functions, including motor skills, coordination, memory, and other cognitive skills. Some antioxidants protect neurons and other cells against oxidative stress. It is therefore believed that these selenoproteins plays a critical role during the stage of pregnancy where the unborn baby’s brain is developed and is particularly vulnerable to oxidative stress.
It is known that a deficiency of GPX4, an antioxidant that protects neurons, can cause ataxia, which is a general term for the loss of the ability to coordinate muscular movement and is known to cause clumsy movements and problems with balance. Baby mice who got a selenium-depleted diet after being weaned showed signs of serious neurological disturbances. These symptoms gradually disappeared when their dietary selenium intake was increased.
Mice who were exposed to an experimental TXNRD deficiency in their nervous system showed signs of stunted growth and movement disorders, indicating that this particular selenoprotein is important for the development and function of the brain.
Several animal studies have already shown that maternal selenium status is important for the immune defense and fertility in the offspring. It is also known that selenium deficiency in humans and livestock can result in ruptured fetal membrane, miscarriage, premature delivery, and low birth weight. However, science has still not studied whether the selenium status of pregnant and breastfeeding women affects their infants with regard to brain inflammation, oxidative stress, and behavior.
Minor selenium deficiency harms the brain development of the offspring
The new Italian study, which is published in Nutrients, was carried out on pregnant and breastfeeding rats. The scientists wanted to see what happened to the brain and nervous system of the offspring of female rats that were fed diets with different selenium content. All pregnant rat mothers got the same diet and calorie amount for up to 40 days after giving birth. The only exception was selenium where the administered diets placed the rats in one of the following three groups: optimal, insufficient, or deficient. The scientists then studied the offspring and analyzed their neurological development and measured different inflammation markers and brain antioxidants.
The researchers observed that even minor selenium deficiency during pregnancy and breastfeeding has a negative impact on the neurological development and health of the offspring. One of the things they observed was that the GPX antioxidant activity was lower in the cerebral cortex and in the liver, which is where the primary synthesis of selenoproteins takes place. They also observed that male offspring was more vulnerable.
How much selenium do we need?
The recommended daily selenium intake in Europe is between 50-70 micrograms daily. The need for selenium increases during pregnancy and breastfeeding, which is why many scientists recommend getting as much as 85-100 micrograms daily to support fetal growth and selenium content in breastmilk. Earlier studies of pregnant women have looked at the effect of taking 100 micrograms of selenium daily. This amount has been seen to prevent ruptured fetal membrane and preeclampsia, which is the leading cause of preterm delivery.
The Danish health authorities advise pregnant women to take supplements of folic acid, iron, and vitamin D. There are different combined supplements for pregnancy that even include selenium. Make sure to choose high-quality supplements so that selenium and the other nutrients are absorbed properly in the body.
- European farmland generally lacks selenium. This affects the entire food chain.
- For decades, Danish farmers have been feeding extra selenium to their livestock to prevent deficiency diseases and poor fertility.
- Several studies show that selenium supplements may support human fertility, pregnancy, and health in general.
Maria Antonietta Ajmone-Cat et al. Critical Role of Maternal Selenium Nutrition in Neurodevelopment: Effects on Offspring Behavior and Neuroinflammatory Profile. Nutrients 2022
Jiaomei Yang et al. Maternal Zinc, Copper, Selenium Intakes during Pregnancy and Congenital Heart Defects. Nutrients 2022
Pol Solé-Navais et al. Maternal Dietary Selenium Intake during Pregnancy Is Associated with Higher Birth Weight and Lower Risk of Small for Gestational Age Births in the Norwegian Mother, Father and Child Cohort study. Nutrients. December 2020
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
Aparna Shreenath. Selenium Deficiency. StatPearls. May 6, 2019
Bent Tolstrup Christensen et al. Selenanvendelse I dansk landbrug. DJF Rapport Nr. 125 2006
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