Are You Deficient In Selenium? These 5 Things May Be Affected By It

Read on to learn about how this essential trace mineral plays a role in keeping you healthy in ways you may not realize.

By Caitlin Shaw3 min read
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Selenium is a trace mineral found in water and soil, but it’s most commonly absorbed through foods like Brazil nuts, walnuts, tuna, cod, beef, and some grains. (A trace mineral is a substance that is needed in only small amounts and typically resides in the muscle tissues of living beings.) Selenium is categorized as an essential trace mineral by nutritionists because it’s considered vital to the prevention of diseases and the overall maintenance of strong health. 

Why Is Selenium Important?

Selenium is such a valuable mineral because it’s a component in selenoproteins and enzymes that have antioxidant properties. If you read health magazines and follow your fair share of fitness influencers, “antioxidant” is probably a word you see a lot – but what does it mean? 

By definition, an antioxidant “protects cells from the damage caused by free radicals.” And a free radical is any unstable molecule produced from the oxidation process which occurs during metabolism. Free radicals can also be found outside the body, and a few examples include pollution, ultraviolet rays, and tobacco smoke. Antioxidants are so healing and beneficial because they remove or diminish the effect of potentially damaging oxidizing agents. Examples of antioxidants are beta-carotene or vitamins A, C, or E.

Risk Groups

Due to our food, water, and soil sources in the United States, a selenium deficiency is rare – but it’s not impossible. Selenium deficiencies are most commonly found in China, Russia, and parts of Europe because the soil in these regions lacks proper selenium levels. It’s estimated that up to 1 billion people globally experience a lack of selenium in their bodies.

Animal products are a great source of selenium, so some vegans and vegetarians struggle to absorb enough selenium.

Aside from living in this region, you could be at an increased risk for selenium deficiency if you suffer from an autoimmune or digestive disorder, have HIV, or undergo dialysis because all these conditions inhibit the body’s ability to absorb proper amounts of nutrients and minerals. Additionally, because meat and animal products are a great source of selenium, sometimes vegans and vegetarians struggle to absorb enough.

According to both the U.S. Department of Health and Human Services and the USDA, the recommended daily amount (RDA) for selenium in women aged 19 and older is 55 micrograms per day. Women who are pregnant or breastfeeding need between 60 and 70 micrograms daily. Selenium is important during pregnancy because it can prevent thyroid dysfunction, diabetes, pregnancy-induced hypertension, oxidative stress, and more. Studies also show that an increased intake of selenium during pregnancy has the potential to reduce the risk of future high blood pressure in babies.


While rare, it’s still important to be aware of the symptoms of selenium deficiency and see your doctor if you begin to experience any of the following frequently. 

  • Nausea and vomiting

  • Headaches

  • Altered mental state or confusion

  • Seizures

  • Poor immune function

  • Hair loss

  • Extreme fatigue

  • Infertility

How Is Your Health Affected by a Selenium Deficiency?

Since selenium is a powerful player in the construction of antioxidants, absorbing the proper amount of selenium is critical to your health. The following list is just five of the many facets of health that could be affected by your selenium intake. 

1. Thyroid

Aside from muscle tissues, the thyroid is where the highest concentration of selenium is found in our bodies. Selenium is a critical element to many of the thyroid-regulating hormones and proteins, so a deficiency will most definitely impact your thyroid function. Research from the Harvard School of Public Health has shown that selenium deficiency has been linked to thyroid conditions like Hashimoto’s disease and Graves’ disease. In both of these conditions, the body produces antibodies that attack the thyroid gland, causing either an overactive thyroid (hyperthyroidism) or an underactive thyroid (hypothyroidism). Additionally, selenium and iodine have a synergistic relationship which is important for a healthy thyroid. 

2. Vision

Selenium and its antioxidant properties also play a role in protecting the lens of your eye. It works by preventing the buildup of dead or useless cells on the lining of your eyeball, therefore keeping your vision clear and strong. Without selenium, your vision could suffer. In addition to your thyroid, your retina contains high concentrations of selenium compared to other parts of the body. Research has shown that a selenium deficiency can lead to a damaged retina, which increases the risk of eye disorders like age-related macular degeneration (AMD) and cataracts – two of the leading causes of blindness.

Selenium protects the eggs, follicle, and endometrium from damaging free radicals.

3. Fertility

Selenium is critical to healthy fertility in both females and males, again because of its antioxidant properties. For starters, selenium aids in the production of healthy estrogen, progesterone, and T4 (thyroid) hormones because these molecules need an oxidative-free environment. Selenium also protects the eggs, follicles, and endometrium from damaging free radicals, ensuring a safe and successful fertilization. Research shows that a lack of selenium could lead to gestational complications, greater risk for miscarriage, or greater risk of damaged immune system in the baby. 

4. Immune System 

If you have a selenium deficiency, you may be more likely to suffer from an autoimmune disease like eczema or psoriasis. In conditions like these, the body cannot distinguish between healthy tissue and damaging agents, causing it to attack itself. A lack of selenium means a lack of antioxidants, which will cause a weaker immune system and leave your body susceptible to harmful substances. On the flip side, selenium has been used to treat those with poor immune function because of its ability to help boost white blood cell count and therefore help the body fight off harmful agents.

5. Muscle Growth and Joint Strength

Again, the antioxidant qualities of selenium mean that its absence can cause a notable impact. Because selenium is critical to hormone and protein production, the deficiency can mean a deficiency in proteins, which in turn, creates weaker muscles and greater fatigue. Antioxidants also reduce the amount of stress we feel in our bodies, so without selenium, our muscles and joints suffer.


Please note this is not advice from a medical professional, and remember that treating a selenium deficiency could look different for each individual. But the two most common approaches to reversing a selenium deficiency are to take oral supplements or to change your diet. Always consult your doctor if you suffer from a selenium (or any other nutritional) deficiency. 

Closing Thoughts

Though a trace mineral and only needed in very small quantities, selenium plays a critical role in regulating our bodily processes like thyroid, fertility, vision, immune system, and muscle function – all because of its antioxidant properties. Selenium is responsible (along with vitamins A, C, E, and zinc) for much of the immune-strengthening work that keeps us healthy. Without these, our bodies become susceptible to all kinds of harmful attackers. A selenium deficiency can cause serious health implications beyond just the ones discussed here, so if you think you could be experiencing any of the signs or symptoms, contact your healthcare provider.

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