Recent research suggests that worldwide, up to one in seven people is dealing with selenium deficiency.
What is selenium and why do we need it? Selenium can help to increase immunity, takes part in antioxidant activity that defends against free radical damage and inflammation, and plays a key role in maintaining a healthy metabolism. You can see then why low selenium intake can be problematic.
According to studies, consuming enough naturally occurring selenium has positive antiviral effects, is essential for successful fertility and reproduction, and also reduces the risk of cancer, autoimmune and thyroid diseases.
Among healthy people in the U.S., a selenium deficiency is believed to be relatively uncommon. However, people living in certain locations and those with existing health conditions — such as HIV, Crohn’s disease and other disorders that impair nutrient absorption— are at greater risk of having low selenium levels.
What Is A Selenium Deficiency?
Selenium deficiency occurs when someone has lower than adequate levels of selenium in their body.
Selenium is a trace mineral found naturally in the soil, in certain high-selenium foods, and even in small amounts in water. Both humans and many other animals require trace amounts on a consistent basis for optimal health.
What is selenium good for in the body? It helps the body thanks in large part to its role acting as an antioxidant. Selenium benefits include: defending against oxidative stress, heart disease and cancer; boosting immunity; regulating thyroid function; protecting against cognitive decline; and boosting fertility.
What happens when you have a selenium deficiency?
Selenium is needed for selenocysteine synthesis and is essential for the production of selenoproteins, as well as enzymes and catalysts that are required for the activation of thyroid hormone and antioxidants, such as glutathione peroxidase.
Your metabolism, heart and brain can all suffer due to the many functions that selenoproteins perform. Production of thyroid hormones suffers when intake is low, while the immune system cannot defend against viruses and infections as well.
The body may become more prone to diseases including cancer because selenium is needed to control production of natural killer cells, T-cells, antibodies and macrophages.
Additionally, cells become more prone to oxidative stress and negative effects of exposure to heavy metals (such as lead, cadmium, arsenic, mercury, etc.) when deficiency occurs. Because selenium is important for brain health, deprivation can lead to cognitive decline, potentially Alzheimer’s disease, and depressed moods and more hostile behavior.
What are the main symptoms of a selenium deficiency?
The most common selenium deficiency symptoms include:
- reproductive issues
- muscle weakness
- brain fog
- thyroid dysfunction
- mood related issues including depressed mood, anxiety and hostile behaviors
- hair loss
- weak, brittle nails
- susceptibility due to illnesses due to a weakened immune system
- confusion and cognitive changes
Having low selenium status is also correlated with an increased risk of some health problems including: mortality due to inflammation, infertility, poor immune function, cognitive decline, and potentially certain types of cardiovascular diseases and cancers.
Selenium deficiency and iodine deficiency are also considered common in people affected by Keshan disease, a cardiovascular disease, and Kashin-Beck disease, a chronic bone, joint and cartilage disorder that is most prevalent in parts of Asia.
Causes and Risk Factors
According to a 2017 article published in the journal PNAS, “insufficient selenium intake has been estimated to affect up to 1 billion people worldwide.” Selenium deficiency risk is also predicted to increase under future climate change.
Certain groups of people are more likely to be deficient in selenium, due to factors like the soil quality where they live, their medical history, genetics and how well they absorb selenium.
While the RDA for selenium for adults is 55 micrograms/daily, the average daily intake of selenium in the U.S. and certain developed nations is believed to be 125 micrograms per day, which exceeds the daily requirement. However, some people are obtaining or absorbing less due to their diets and gastrointestinal health.
Some factors that can contribute to low selenium levels include:
1. Low selenium content in soil
The amount of selenium in soil differs a lot depending on the location, due to factors like amount of rainfall, evaporation and pH levels.
For example, certain studies show concern that parts of Eastern Europe and Africa have soil low in selenium levels, so populations living in those areas may be suffering from compromised immunity because of this. One review found that intake and status is “suboptimal” in European and Middle Eastern countries, especially Eastern European nations.
According to research, populations in the U.S. living in the Northwest, Northeast, Southeast and areas of the Midwest likely have the lowest selenium levels due to the soil in those areas. These populations average consuming 60 to 90 micrograms per day, which is still considered to be adequate intake but less than other populations where the soil is more selenium-rich. Soil in the Great Plains and the Southwest of the U.S. have been found to have mostly adequate selenium content.
2. Low intake from food sources
The amount of selenium in foods is largely dependent on soil conditions that the food grew in — therefore even within the same food, levels of selenium can vary widely. This means that higher selenium concentrations are found in crops grown in certain locations more so than others.
Not eating selenium foods very often, such as meat, fish and/or poultry, also increases the risk for having low levels (meaning that vegetarians and vegans may potentially be at an increased risk).
Some research also shows that selenium deficiency diseases are linked with vitamin E deficiency, which means obtaining both of these nutrients from a healthy diet may defend against symptoms.
3. Health conditions that affect levels
Being affected by Kashin-Beck disease, a chronic bone disorder, is associated with deficiency. Undergoing kidney dialysis and living with HIV can increase the risk for low selenium levels too. Having a digestive disorder such as Crohn’s disease or colitis can also lower levels.
Liver cirrhosis is another risk factor, since selenium is metabolized by the liver to selenide, which is the form of the element required for the synthesis of selenoproteins.
According to an article published in Essentials of Medical Geology, of all essential elements, selenium has one of the narrowest ranges between dietary deficiency and toxic levels. The body tightly controls selenium levels, so too much or too little can both be problematic.
The recommended daily allowance for selenium depends on your age and is as follows, according to the USDA: (9)
- Children 1–3: 20 micrograms/day
- Children 4–8: 30 micrograms/day
- Children 9–13: 40 micrograms/day
- Adults and children 14 and up: 55 micrograms/day
- Pregnant women: 60 micrograms/day
- Breastfeeding women: 70 micrograms/day
If you have a condition that puts you at risk for selenium deficiency, you may want to have your levels tested to see if you can experience additional selenium benefits by taking a supplement. To find out your current selenium levels, you can have a blood or hair test done by your doctor.
Your doctors will also discuss with you any selenium deficiency symptoms you may be experiencing — such as hair loss, fatigue, etc. In addition, you have levels of the enzyme called glutathione peroxidase tested, since this is needed to maintain normal selenium levels.
Keep in mind that a blood test will only show you the amount of selenium you’ve acquired recently. It’s believed that the accuracy of hair tests is not very consistent, since the mineral is stored differently throughout different organs and systems. For example, your thyroid stores more selenium than anywhere else in the body because selenium plays a big part in metabolic processes.
Conventional and Natural Treatments
Here’s the good news: Because experts don’t often find selenium deficiencies in populations that are generally not malnourished or who have compromised immunity, it’s believed that as long as you include natural food sources of selenium in your diet regularly and are otherwise healthy, there is a only a small chance you will suffer a deficiency.
Here are several ways you can help prevent and treat selenium deficiency:
1. Eat Foods High in Selenium
What foods are high in selenium? Some of the top selenium foods to include in your diet are: Brazil nuts, eggs, liver, tuna, cod and other fish, sunflower seeds and chia seeds, poultry, certain types of meat, barley, and mushrooms.
Whole foods are the best sources of selenium, especially when these foods are handled and prepared in a delicate way, since selenium may be destroyed during processing and very high-heat cooking methods.
Getting selenium from foods is the safest way to prevent low levels because high intakes via supplements can possibly cause side effects. Taking more than 900 mcg per day can be toxic, however getting this amount from foods alone is extremely unlikely.
In the future we may see more countries fortifying soil with additional selenium (such as in the form of yeasts) to help bring levels up in the food supply. In many countries, eggs, meat and milk products that are fortified with selenium are also now available.
2. Consider Taking a Selenium Supplement
Selenium is found in vitamin supplements including many multivitamins. Adults should take up to 55 micrograms daily, such as in the form of selenomethionine or selenite, while pregnant women can take up to 60 mcg/day and lactating women up to 70 mcg/day.
While 55 mcg/day is the standard recommended amount, some experts believe that the goal of supplementation should be to achieve about 70 to 90 mcg/day for adults.
Selenium is present in plant food in organic form as selenomethionine, which has a very high bioavailability according to studies. Inorganic forms are also available, such as selenate and selenite, also which are highly bioavailable.
It is important to note that if you already consume proper amounts of selenium from a healthy diet, consuming more selenium may not be beneficial, and high doses exceeding 400 to 900 micrograms can even be harmful due to causing selenium toxicity. Therefore, do not exceed recommendations by supplementing with very high doses without consulting with a physician first.
An overdose of selenium may possibly cause reactions like bad breath, fever, nausea and potentially liver complications — or even kidney and heart problems — although these only occur at very high levels of selenium that reach “poisoning” status.
- Selenium is a trace mineral found naturally in the soil and also in certain foods and water.
- Selenium benefits the body in many ways, such as by defending against oxidative stress, inflammation, heart disease, infertility, asthma and even cancer.
- Deficiency in this mineral is relatively rare, but is more likely to affect people with certain health conditions, those with impaired immunity, those who avoid selenium foods, and people living in certain parts of the world where the soil has a low mineral content.
- Selenium deficiency symptoms can include: hair loss, reproductive issues, muscle weakness, fatigue, brain fog and thyroid dysfunction.
- Include selenium foods in your diet to help bring levels up. The best sources include: Brazil nuts, eggs, sunflower seeds, liver, fish, turkey, chicken breast, chia seeds and mushrooms.
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