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Selenium Benefits for Health, Plus Dosage Recommendations

Selenium is a vital mineral for the human body that has numerous roles. What is selenium used for? It increases immunity, takes part in antioxidant activity that defends against free radical damage and inflammation, and plays a key role in maintaining a healthy metabolism.

According to studies, consuming foods with selenium — such as Brazil nuts, eggs, liver, tuna, cod and sunflower seeds — and/or taking selenium supplements can have positive antiviral effects, supports fertility and reproduction, and may even reduce the risk of cancer, autoimmune and thyroid diseases.

What Is Selenium?

Selenium is a trace mineral that is found naturally in the soil and also appears in certain high-selenium foods. There are even small amounts in the water you drink.

What is selenium good for in the body? Something that makes selenium nutrition valuable is its role in antioxidant activity. As a component of antioxidant enzymes, particularly glutathione reductase, it’s key for repairing tissues throughout the body.

Because it both increases antioxidant capabilities and the quality of blood flow, it can help to enhance resistance against diseases and effects of stress. Its ability to fight oxidative stress and and inflammation are thought to be due to different types of selenoprotein found in selenium.

Among healthy people in the U.S., a selenium deficiency is believed to be uncommon. However, people with certain health conditions, such as HIV, Crohn’s disease and other disorders that impair nutrient absorption, are associated with having low levels that can lead to deficiency.

Top 8 Selenium Benefits

1. Acts as an Antioxidant and Defends Against Oxidative Stress

Selenium benefits include the ability to fight the aging process and help the immune system by reducing free radical damage. It has a synergistic effect with other antioxidants like vitamin E, enabling the body to defend against cancers like prostate and colon cancer.

As an essential component of glutathione peroxidase, selenium helps carry out important enzyme processes that protect lipids (fats) in cell membranes. It’s needed to fight oxidative degradation of cells and protect against mutation and DNA damage that can cause disease.

2. May Help Defend Against Cancer

Selenium is especially helpful if you have a weak immune system or a history of cancer in your family. Selenium supplementation at high doses has been shown to potentially have anti-cancer effects. According to studies, it may be effective at reducing the risk of cancer incidence, cancer-caused mortality and severity of cancers — specifically in the liver, prostate, colorectal and lungs.

Because it has the special job of activating selenoproteins, selenium acts in an enzymic role that helps antioxidants to do their job best. There is evidencethat selenium benefits include not only being able cut cancer risk, but also help to slow down existing cancer progression and tumor growth.

Studies have shown that a high dose of 200 milligrams a day can be effective in protecting DNA, which can reduce the risk for cell mutation and cancer development.

Other studies show that in areas of the world where the soil is lowest in selenium, cancer risk is increased when compared to areas that have higher levels naturally available.

Selenium benefits - Dr. Axe

3. Can Help Boost Immunity

According to recent research, selenium is needed for the proper functioning of the immune system and can also be a key nutrient in counteracting the development of viruses, including HIV.

In patients who already contracted HIV, it’s been shown to also be useful in slowing down the progression of the disease into AIDS.

4. Improves Blood Flow and May Lowers Risk for Heart Disease

Low selenium concentrations are associated with an increased risk of cardiovascular disease. Supplements or an increase of selenium-rich foods may be able to help prevent coronary heart disease.

It’s believed that it can benefit heart health due to its ability to fight inflammation, increase blood flow, reduce free radical oxidative stress and help with antioxidant activity.

5. Helps Regulate Thyroid Function

Research now suggests that there is a link between thyroid metabolism and selenium deficiency. Selenium acts as a catalyst for the production of active thyroid hormones.

If you imagine that your body is a manufacturing facility, then your thyroid would be the main boss in charge of regulating the whole operating system, so when the thyroid isn’t working properly, there are many serious, noticeable consequences.

The thyroid gland controls numerous important everyday body functions, including appetite, sleep, temperature, weight, energy and more.

A problem with proper thyroid function can result in negative symptoms, such as irritability, muscle weakness, fatigue, weight gain or loss, trouble sleeping, and many other reactions — therefore acquiring proper amounts of selenium benefits the thyroid and body in many important ways.

Selenium acts as a powerful protector of the thyroid, and it regulates the production of reactive oxygen within the gland and protects it from antibodies that can create thyroid disease.

For these reasons, selenium benefits are also being investigated to see if they can help patients with Hashimoto’s disease, Grave’s disease and in pregnant women with anti-TPO antibodies.

6. May Help Increase Longevity

Certain studies have investigated the use of selenium for the treatment of dozens of conditions that range from asthma to arthritis, thyroid disorder and heart disease. The risk of these conditions increase as we age, so consuming selenium can help defend the body and may contribute to a longer life.

7. Helps Reduce Asthma Symptoms

Observational studies have demonstrated that patients with chronic asthma may have lower levels of selenium. According to studies, when people with asthma took selenium supplements, they experienced less asthma-related symptoms than those who took a placebo.

Experts think that selenium supplementation may be a useful add-on treatment to medication for patients with chronic asthma. However, more research is needed before this becomes a regular practice, as researchers have yet to determine selenium’s full effect on lung function.

8. Can Help Boost Fertility

Selenium is required for proper sperm motility and also increases blood flow, two key components involved in conception and beating infertility. It is incorporated in the sperm mitochondria capsule and may affect the behavior and function of the sperm as they move through the vaginal canal.

It appears that both low and high sperm selenium concentrations can have a negative influence on the number of sperm, therefore aiming to meet the recommendation, but not to far exceed it, is important for fertility.

Some studies also show that selenium may even reduce the risk of miscarriage, but at this point more research has been dedicated to infertility in men than in women when it comes to selenium supplementation.

Supplementation and Dosage Recommendations

Selenium is a trace mineral, which means we only need a small amount of it. However, the body is able to flush selenium out of your system somewhat quickly since it plays an actionable role in many important body functions — therefore it’s important to consume it regularly, especially as you age, in order to take advantage of its benefits.

Some doctors, such as naturopaths, may recommend selenium supplements to treat acne, asthma, tendinitis, male infertility problems and postmenopausal disorders in women, among other conditions.

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 reaching 400 micrograms can even be harmful.

The recommended daily allowance for selenium depends on your age and is as follows, according to the USDA:

In supplement form, selenium is available in the form of selenomethionine and selenium selenite. Selenomethionine is usually easier for most people to digest and absorb properly.

When taking selenium supplements, most adults should take up to 55 micrograms daily (such as of selenomethionine), while pregnant women can take up to 60 micrograms and lactating women can take up to 70 micrograms.

The tolerable upper limit of selenium is 400 mcg per day.

Experts warn that it’s crucial that the public understands that selenium benefits work best when levels are met through eating foods with selenium. No one should exceed recommendations by supplementing with very high doses without consulting a physician.

Selenium sulfide is another form you may come across. This type is the active ingredient often found in shampoos used for the treatment of dandruff.

Best Selenium Foods

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.

What food is highest in selenium? That would be Brazil nuts. Just one single nut provides more than 100 percent of the daily selenium you need, roughly 68 to 91 micrograms (mcg).

Here are the top foods high in selenium:

  1. Brazil nuts
  2. Salmon
  3. Tuna
  4. Turkey
  5. Cottage Cheese
  6. Chicken
  7. Mushrooms
  8. Halibut
  9. Eggs
  10. Navy beans
  11. Sardines
  12. Sunflower seeds
  13. Grass-fed beef
  14. Oats
  15. Beef Liver

Selenium foods - Dr. Axe

To add more selenium to your diet naturally, try any of the recipes below that feature foods rich in selenium.

Causes of Selenium Deficiency

Selenium can be found in soil and from food sources, however certain groups of people are more likely to be deficient.

There are actually four naturally occurring types of the trace mineral selenium. The four natural states of selenium are: elemental selenium, selenide, selenite and selenate.

Two types, selenate and selenite, are found predominantly in water, whereas the other two types are the kinds found in soil and therefore in food sources. For humans, the primary pathway of consuming selenium is through food, followed by water and then by air.

Suffering from a selenium deficiency is correlated with an increased risk of health problems including mortality due to inflammation, infertility, poor immune function and cognitive decline. While not as serious, deficiency symptoms can include reproductive issues, muscle weakness, fatigue, brain fog, thyroid dysfunction, and hair loss.

While the RDA for selenium for adults is 55 micrograms/daily, the average daily intake of selenium in the U.S. is believed to be 125 micrograms per day, which far meets the daily requirements.

Some contributing to causes to selenium deficiency can include:

Testing for selenium deficiency:

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, however these are not believed to always be very accurate.

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, you probably don’t need to be tested unless at your high risk. 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 could suffer a deficiency that could lead to any serious risks.

Precautions and Side Effects

What are the side effects of taking selenium? Taken at normal doses, selenium does not usually have negative side effects.

An overdose of selenium (selenium toxicity) 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 that reach “poisoning” status.

Again, the toxicity of most forms of selenium is rare and usually only experienced in people who supplement with high doses. Too high of levels can lead to potentially fatal complications including heart attack and respiratory (lung) depression.

The U.S. National Toxicology Program also lists certain types of selenium as an animal carcinogen, but there is no evidence that all types can harm animals and that this poses a serious risk in everyday situations.

Selenium may also interact with other medicines and supplements. These include antacids, chemotherapy drugs, corticosteroids, niacin, cholesterol-lowering statin drugs and birth control pills. If you take any of these medications, it’s best to speak with your doctor before supplementing.

Final Thoughts


By Jillian Levy, CHHC

August 22, 2019


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