You may not have heard about selenium, but this mineral is very important for your health. Different foods and supplements contain selenium, and low selenium levels can cause a range of symptoms.

Keep reading to find out more about selenium, its functions, dietary sources, and symptoms of selenium deficiency.

What is selenium?

According to the Harvard T.H. Chan School of Public Health, selenium is a trace mineral that your body needs to perform certain functions. Most selenium in the human body is stored inside the muscle tissue, although your thyroid gland also has a high concentration of this mineral. Selenium is essential for human health.

The recommended dietary allowance (RDA) of selenium is approximately 55mcg per day for healthy adults. Women who are pregnant or breastfeeding need slightly higher amounts of selenium, around 60-70mcg each day.

The tolerable upper intake level (UIL) is the maximum amount of selenium that you can take without adverse effects. The UIL for selenium is around 400mcg per day.

Functions of selenium

Despite being a trace mineral, selenium plays many roles inside your body. According to Oregon State University, selenium is part of the amino acid selenocysteine. Selenocysteine can be found in at least 25 different proteins, which are known as selenoproteins.

These proteins have different functions. According to the National Institutes of Health, selenoproteins are involved in DNA synthesis, reproduction, metabolism of thyroid hormones, protection against oxidative stress, and prevention of infections. It could also help protect against certain cancers.

Oxidative stress releases free radicals that can harm your cells and DNA. According to Mount Sinai, these free radicals can accelerate aging and increase your risk of different health conditions, such as heart disease. It has been theorized that selenium could protect against free radicals by lowering your levels of oxidative stress.

Causes of selenium deficiency

Most cases of selenium deficiency are caused by not consuming enough of this mineral in your diet. Selenium deficiency is extremely rare in healthy, well-fed individuals.

Low selenium is more likely to affect people who:

Are malnourished
Have undergone gastric bypass
Have a condition that impacts your intestinal absorption
Are over the age of 90 years old
Require kidney dialysis
Are living with HIV/AIDS

Selenium deficiency symptoms

Low selenium symptoms can include:

Nausea and vomiting
Headaches
Altered mental state
Confusion
Fatigue
Lethargy
Fertility problems
Depressed mood
Hair loss
Frequent infections
Mental fog
Muscle weakness
Seizures
Coma

Severe selenium deficiency can impair your response to oxidative stress, which can increase your risk of other diseases. For example, certain types of heart and bone diseases are more prevalent in areas of Asia where there are high levels of selenium deficiency.

Keshan disease is caused by selenium deficiency and triggered by a viral infection, and it can damage the walls of the heart.

Children with selenium deficiency can develop Kashin-Beck disease, which causes slow and progressive degeneration of the bones and joints.

Sources of selenium

Selenium can be found in many different foods, including:

Whole grains
Dairy products
Fortified cereals
Brazil nuts
Sunflower seeds
Fish
Shellfish
Turkey
Chicken
Beef
Beans
Lentils
Eggs

Selenium is destroyed when foods are processed, so it’s important to include whole foods in your diet to get enough selenium. You can also find selenium in many daily multivitamins.

You shouldn’t take more selenium than the UIL, unless it’s prescribed by your doctor. Just like any other substance, selenium can cause toxicity if you take it in large amounts. Selenium toxicity isn’t common, but it can happen due to acute toxicity or chronic exposure to high doses of selenium.

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