Selenium is an essential trace mineral that is required in small amounts by the body for optimal health. Deficiency of selenium can lead to various health problems, including weakened immune function, thyroid dysfunction, impaired reproductive health, and increased risk of chronic diseases. However, excessive intake of selenium can also be harmful and cause toxicity. It is important to maintain a balanced intake of selenium through a varied diet that includes sources such as lean meats, seafood, nuts, seeds, and whole grains.

Through this article, let’s dig deep into the role of selenium in the body, its deficiency causes, and associated symptoms.

What are the Symptoms of Selenium Deficiency?

Some of the common symptoms of selenium deficiency include:

1) Weakened Immune System: Selenium is important for a healthy immune system. Deficiency can lead to a weakened immune response, making individuals more prone to infections and illnesses.

2) Muscle Weakness & Fatigue: Selenium is necessary for proper muscle function. Deficiency can lead to muscle weakness, fatigue, and decreased stamina.

3) Hair Loss & Brittle Nails: Selenium plays a role in maintaining healthy hair and nails. Deficiency can result in hair loss, thinning hair, and brittle nails.

4) Cognitive Impairments: Selenium is important for brain health and cognitive function. Deficiency may lead to cognitive impairments such as poor memory, difficulty concentrating, and brain fog.

5) Thyroid Problems: Selenium is essential for the production of thyroid hormones, which help regulate metabolism. Deficiency can contribute to thyroid dysfunction, leading to symptoms such as weight gain, fatigue, and mood changes.

6) Reproductive Issues: Selenium is involved in reproductive health and fertility. Deficiency can lead to reproductive problems in both males and females, including infertility.

7) Weakened Bones: Selenium deficiency may contribute to weakened bones and an increased risk of osteoporosis.

It should be noted that severe selenium deficiency is rare, but milder deficiencies can still result in some of these symptoms. If you suspect a selenium deficiency, it is important to consult a healthcare professional for proper diagnosis and treatment.

What Causes Selenium Deficiency?

Selenium deficiency can be caused by a variety of factors, including:

1) Inadequate Dietary Intake: Selenium deficiency can occur when the diet does not provide enough selenium-rich foods. This is more common in regions where the soil is low in selenium content, leading to a deficiency in crops and animal feed.

2) Low Selenium Levels in Soil: The selenium content of soil differs across geographic regions. Areas with low selenium levels in the soil are more likely to have selenium deficiency in plants, leading to lower dietary intake of selenium.

3) Medical Conditions: Certain medical conditions like Crohn’s disease, celiac disease, or surgical removal of part of the stomach or intestines can impair the absorption of selenium, leading to deficiency.

4) Increased Requirements: Certain individuals may have an increased requirement for selenium, such as pregnant and breastfeeding women or people with certain medical conditions, which may lead to deficiency if their dietary intake is not sufficient.

5) Alcohol Abuse: Chronic excessive alcohol consumption can adversely affect the absorption and utilization of selenium, leading to deficiency.

6) Medications: Some medications, such as certain antacids, anticonvulsants, or chemotherapy drugs, can interfere with selenium absorption or increase excretion, contributing to deficiency.

7) Heavy Metal Exposure: Exposure to certain heavy metals, such as mercury, can impair selenium utilization in the body and lead to deficiency.

It is important to note that selenium deficiency is relatively rare in most parts of the world, as it is usually obtained in sufficient amounts through a balanced diet.

Dietary Sources of Selenium

Dietary sources of selenium include:

  • Seafood: Fish and shellfish, especially tuna, salmon, sardines, cod, and shrimp, are good sources of selenium.
  • Meat: Poultry, such as chicken and turkey, and red meat, like beef and lamb, contain selenium.
  • Grains: Whole wheat bread, oatmeal, brown rice, and other whole grains are also sources of selenium.
  • Nuts & Seeds: Brazil nuts are one of the best sources of selenium. Other nuts and seeds, such as sunflower seeds, flaxseeds, and chia seeds, also contain selenium.
  • Legumes: Beans, lentils, and peas are good sources of selenium.
  • Dairy Products: Milk, cheese, and yogurt contain small amounts of selenium.
  • Eggs: Eggs are a good source of selenium.
  • Vegetables: Some vegetables, such as broccoli, spinach, asparagus, and mushrooms, contain selenium.
  • Fruits: Fruits like bananas, oranges, and strawberries also contain small amounts of selenium.

It’s important to note that the selenium content in these foods can vary depending on the soil in which they were grown, so the actual amount of selenium can vary.

Role of Selenium in the Body

Selenium is an essential trace mineral that plays a crucial role in various biological processes within the human body. Some of the key roles of selenium include:

1) Antioxidant Activity: Selenium is a component of several antioxidant enzymes, including glutathione peroxidase, which helps protect cells and tissues from oxidative damage caused by harmful free radicals.

2) Thyroid Function: Selenium is required for the proper functioning of the thyroid gland. It is involved in the conversion of the thyroid hormone thyroxine (T4) into its active form, triiodothyronine (T3), which is essential for maintaining a healthy metabolism.

3) Immune System Support: Selenium is necessary for the normal functioning of the immune system. It helps regulate the production and activity of immune cells and promotes the body’s defense against infections.

4) DNA Synthesis & Repair: Selenium is involved in DNA synthesis and repair processes, which are crucial for maintaining the integrity of genetic material and preventing mutations.

5) Reproductive Health: Selenium is important for male and female fertility. It is necessary for the production of healthy sperm, and in females, it supports the development of healthy eggs and a successful pregnancy.

6) Cardiovascular Health: Selenium helps reduce the risk of cardiovascular diseases by inhibiting the oxidation of lipids (fats) in the blood, reducing inflammation, and improving blood vessel function.

7) Cognitive Function: Selenium may play a role in maintaining cognitive health and reducing the risk of cognitive decline, although more research is needed in this area.


Overall, selenium is essential for several physiological functions, and a deficiency in this mineral can lead to various health problems, including weakened immune system, thyroid dysfunction, impaired fertility, and increased risk of chronic diseases.