Selenium is crucial for thyroid health, but it also plays a large role in other areas of our health. A big part of its importance in the body is the fact that it is a powerful antioxidant. Selenium protects the body from stress and inflammation because of its antioxidant properties. This is part of why it’s so beneficial for our immune system as well. Selenium also works as an antioxidant to protect our cells from damage, which supports the overall health and function of different organ systems in the body. It’s also been shown to be protective against Alzheimer’s and cognitive decline in older individuals. Let’s break down exactly how it helps our thyroid as well as other areas of our health like fertility and iron status.
Selenium impacts our thyroid in three major ways:
Selenium helps convert T4 (inactive thyroid hormone) to T3 (active thyroid hormone). T3 is what acts on our cells and supports our metabolism. Without adequate T3 levels, we can experience hypothyroid symptoms. When it comes to protecting the thyroid against oxidative stress, there are a few proteins that are powered by selenium that do this such as glutathione peroxidases and thioredoxin reductase. Finally, what I think is one of the coolest functions if selenium when it comes to thyroid health is how it powers deiodinases. These are proteins that gather iodide from inside the thyroid gland when thyroid hormone is being produced. They are essential for recycling thyroid hormone. If we didn’t have them, we would lose a lot of iodine and thyroid hormones in the urine.
Because selenium powers the glutathione peroxidase enzyme and protects cell membranes from oxidative stress and also supports thyroid health, it is very important for fertility for both men and women.
Selenium deficiencies in men have been shown to contribute to infertility by causing a deterioration in the quality of semen and sperm motility. Understanding your selenium status before trying to conceive is important for both men and women. Studies using vitamin E and selenium supplements have been shown to increase sperm motility. There’s research that shows a selenium deficiency may be one of the leading causes of infertility in men because of how it impacts sperm quality and motility.
Adequate thyroid hormone is essential for ovulation to occur and to carry out a healthy pregnancy. There is a huge connection between miscarriages (especially recurrent miscarriages) and thyroid health. We now know that selenium is essential for a healthy thyroid. It’s also important for a healthy baby. Selenium deficiencies may lead to pregnancy complications, miscarriages, and damage to the nervous and immune system of a baby. Studies have also shown that low levels of selenium in the blood are a good predictor of low birth weight of a newborn.
Low selenium levels are associated with anemia in older women. There’s still more research that needs to be done for exactly how selenium impacts iron status, but we know that the lower selenium is, the higher the risk of anemia is. I think one obvious reason could be because many foods that are rich in copper and iron are also great sources of selenium, so if someone isn’t getting adequate iron or copper-rich foods in their diet, chances are, they aren’t getting enough selenium either. There’s also a connection between selenium, inflammation, and hepcidin. Studies show there is an inverse relationship between selenium and hepcidin. If you’re new, hepcidin is a protein made in the liver that impacts iron status. When we don’t have enough iron, hepcidin levels decrease and we absorb more. When we have too much iron, hepcidin levels increase and block iron absorption and movement. Low selenium is associated with an increase in hepcidin. This means that selenium deficiencies are seen with high hepcidin levels, which would block iron absorption and movement in the body. Even though the body has enough iron, it is being stored and sequestered in the cells. This is often seen with anemia of chronic inflammation. This would make sense since selenium is such a powerful antioxidant. If we don’t have enough, then we could experience more inflammation. I don’t think selenium is the only piece of the puzzle when it comes to iron deficiency (clearly, since I did two full podcast episodes on it), but I thought this was another marker to consider when assessing iron status and shows how complex it really is.
Fertility
Thyroid
Iron
If you are enjoying nerding out about selenium, make sure you listen to this podcast episode of the Are You Menstrual? Podcast episode where I do a deep dive into selenium.
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