selenium deficiency

Selenium plays a significant role in the endocrine, immune, and cardiovascular systems. Selenium can also be found in high quantities in the thyroid gland, responsible for keeping up the body’s metabolism.

Selenium is a trace element and essential mineral that the body cannot produce for itself.
Many proteins that carry out varied roles throughout our bodies require selenium to work.

Selenium deficiency can result in nonspecific symptoms like fatigue and brain fog. But it can also cause severe issues like infertility and heighten the effect of certain viruses if one gets infected.

Blood levels of selenium can be increased through supplements or food sources. The enzymes that transform the thyroid hormone thyroxine (T4) to triiodothyronine (T3) are selenium-dependent.

Selenium, which is also a trace element, is involved in DNA synthesis, selenium is also necessary for reproduction and protects the body against infections and diseases.

Although grownups do not require a lot of selenium, they still need some to keep significant systems in the body functioning at an optimum level. The recommended daily allowance (RDA) for adults about the age of 14 is 55 micrograms (mcg) daily.

However, this number plummets to 60 mcg for Pregnant women and 70 mcg for breastfeeding women, according to the Office of Dietary Supplements, 2019.

What do you need to know about selenium deficiency?

Selenium quantity varies significantly from one country to another because the selenium quantity of food items is determined by how much of this mineral is found in the soil in which it grows.

Some parts of the United States have soil rich in selenium soil than other parts, but Europe has soil typically with lower selenium levels than America.

Low soil selenium, and therefore a higher chance of deficiency, is more common in other parts of the world like Eastern Europe, China, and New Zealand.

In the case of New Zealand, this got better when the country started importing wheat high in selenium (Office of Dietary Supplements, 2019). Finland took a similar route and began adding selenium to its fertilizer.

This absence of selenium in the soil can even affect the livestock like Cattle, Sheep, and goats, who eat a vitamin E and selenium-deficient diet, which can make them develop a disorder called white muscle disease wherby the muscles deteriorate from oxidative damage.

Worldwide, about 500 million to 1 billion people have selenium deficiency (Shreenath, 2019). In Canada and the united states of America, selenium deficiency is uncommon, but there are a set of persons who are at a higher risk of suffering from this deficiency.

People suffering from dialysis have a higher chance of developing a defect, those infected with HIV as well as Gastrointestinal conditions such as Crohn’s disease and celiac disease can also make it difficult for people to absorb the selenium they need.

Selenium is an essential mineral. It’s required for many processes, such as:

Selenium deficiency is not having enough selenium in your system. And this can result in several health complications.

The quantity of selenium in food sources is primarily due to the quality of the soil used to grow them. Rainfall, evaporation, and pH levels can affect selenium concentration levels in the soil.

This makes selenium deficiency more common in some parts of the world and not others. However, an estimated 1 billion people worldwide suffer from selenium deficiency, according to a review carried out in 2017.

This same review foretells that the effects of climate change will gradually reduce soil selenium level concentrations in different parts of the world, including the Southwestern United States.

What does selenium do?

Selenium is a particularly essential mineral because it enhances the role of various cardiovascular, endocrine, and immune systems. The thyroid, which is a part of the endocrine system, has the highest concentration of selenium per weight of organ tissue.

A 2011 reviewTrusted Source indicates that there may be a link between selenium deficiency and some types of cancer. However, more study is needed to make any firm conclusions.

Selenium deficiency might also affect cognitive functioning, but again, more research is needed in this area.

Who’s at risk?

Apart from living in an area with soil deficient in selenium, these additional things can also increase one’s risk of selenium deficiency, regardless of where they live:

  • Undergoing dialysis treatment
  • Being HIV positive
  • Having a digestive infection, such as Crohn’s disease
  • Each of the above-listed things can affect the body’s absorption of selenium, even when one is getting enough selenium intake through their diet.

Who is adequate selenium, especially crucial for?

Adequate selenium is particularly essential for some groups, such as people who:

  • Pregnant women
  • Have thyroid diseases like Graves disease
  • Have thyroid nodules
  • Have cancer
  • Have weakened immune function
  • Are already deficient

Selenium deficiency can be difficult for doctors to diagnose. This is because there isn’t a widely available test for it. In some cases, the doctor can measure one’s levels of glutathione peroxidase.

This is an enzyme that needs selenium to function. Consequently, if the level of Glutathione peroxidase is low, there is a likelihood of selenium deficiency.

How is this deficiency treated?

The first type of treatment for selenium deficiency is to consume foods that are rich in selenium. Selenium-rich foods can include but are not restricted to:

  • Beans
  • Yellowfin tuna
  • Rice
  • Brazil nuts
  • Whole-wheat bread

The National Institutes of Health proposes that people over the age of 14 should consume 55 micrograms (mcg) of selenium daily. And for pregnant or lactating women , to take in 70 mcg daily.

Although a daily intake of selenium, over 900 mcg can be toxic and dangerous to one’s health. Indicating symptoms of excessive selenium include a garlic-like odor on one’s breath and a metallic taste in the mouth.

When foods high in selenium are not available, selenium supplements can be beneficial. Many multivitamins contain selenium, but one can also find it as a single product.

Selenium supplements can come in the form of selenomethionine or selenite. Selenomethionine tends to be easier for the body to absorb so that it may be the right choice for more severe deficiency cases.

The U.S. Food and Drug Administration doesn’t regulate the purity or quality of supplements like they do for drugs. So patients should consult with doctors before taking any supplements.

Signs and symptoms of selenium deficiency

selenium deficiency

So what does a selenium-deficient individual experience? Here are some of the signs they might experience if one is not getting enough of the trace mineral.

However, symptoms can differ from person to person, and it’s important to know that one may be deficient and only suffer some of these symptoms. Also, selenium deficiency on its own does typically not induce symptoms or illness.

For any of the below to materialize, additional concerns (such as other nutritional deficiencies) are present.


As nonspecific as this symptom is, as it is shared with different mineral deficiencies, it is indicating signs of selenium deficiency. It’s repeatedly reported with selenium deficiency and may have to do with the role this mineral plays in the thyroid function.

Foggy mental state

Mental fog can happen if one’s selenium intake becomes low enough to cause deficiency. This symptom is nonspecific but can help the healthcare provider diagnose when considered in combination with other signs.

A study found out that low selenium levels were associated with a more reduced function on cognitive tests by older adults, though more researches are required (Shahar, 2010).

Weakened immune system

Low levels of selenium may make one more defenseless to infectious diseases or even turn others harmless pathogens into life-threatening illnesses.

Researchers believe this happened in Keshan disease cases, which amassed attention after affecting a region of China where the soil was significantly deficient in selenium.

This disease is caused by selenium deficiency strengthened with coxsackievirus infection (this virus is responsible for, mouth foot, and hand disease).

Research disclosed that selenium deficiency intensifies the virus’s ability to cause cardiotoxicity, a situation in which there’s damage to the muscle of heart that can arbitrate blood flow (Levander, 2000).

Hair loss

Thyroid hormone plays an essential role in our hair growth and regeneration (Gutkind, 2015). Without selenium, the production of the thyroid hormone is reduced (Ventura, 2017).

The cells in hair follicles react to this drop in thyroid hormone, and one’s hair may fall out abnormally.

Muscle weakness

When we talk about muscles, we are referring to the skeletal muscles precisely and not about the cardiac muscles.

Skeletal muscle disorders that can induce fatigue, weakness, and pain have been discovered in patients with low selenium levels (Chariot, 2003). But selenium deficiency can also affect the heart muscles, as it does in the case of Keshan disease.

One can also suffer from muscle weakness when receiving parenteral nutrition (when one is fed food via an IV, bypassing the digestive system completely) because liquid food is usually low in this micronutrient (Baptista, 1984).


Deficiencies in this trace nutrient can not only cause issues with infertility but can also cause problems during gestation for women who get pregnant while deficient of selenium. There’s a link between selenium levels and fertility.

Still, low levels in the early stages of pregnancy are also associated with miscarriage, low birth weight, and damage to the fetus’ immune and nervous system (Pieczyńska, 2015).

Diagnosis of selenium deficiency

Selenium deficiency can be diagnosed with a blood test, which means recent selenium intake. Hair or nail samples can also be taken, which gives an indication of long-term selenium status.

Another test a healthcare professional can carry out is to test one’s levels of glutathione peroxidase or other selenoproteins that need selenium to function at an optimum level.

Treatment of selenium deficiency

Correcting low selenium requires an increased dietary intake, selenium supplementation, or a combination of both options.

Selenium supplements, typically made from sodium selenite or l-selenomethionine, can be used by healthcare professionals if the deficiency is chronic. Otherwise, taking a multivitamin or including food sources of dietary selenium can be sufficient to get serum selenium to a healthy level.

Plant sources of selenium posses selenomethionine, a form of selenium that’s 90% bioavailable. Meat, seafood, and dairy products are all important sources, although vegans can find it difficult to meet dietary reference intakes through food solely.

But once selenium levels are back into healthy levels, one Brazil nut (the most potent food source of this trace mineral) many times a weekly can be sufficient to keep the selenium levels steady.

But one should consult a health professional who can assess one’s individual needs and proffer professional advice. It’s even more critical for some people to have healthy levels of selenium and, potentially, to bring up deficiencies faster.

That includes people with thyroid nodules, and other thyroid conditions like cancer, Graves disease, or weakened immune system.

Once one’s healthcare provider gives suggestions on dosage and supplementation, it is recommendable to follow the medical advice you’re given. It’s important to keep in mind that the range of optimal daily intake for selenium is slimmer than for other minerals.

While supplementation may be helpful for those who have low consumption, supplementation could cause issues in those who have an average or high intake. Selenosis, or selenium toxicity, is harmful and can cause side effects such as hair loss, fatigue, nausea, and vomiting.