Selenium for Health 

By Jillian Levy, CHHC

November 27, 2017

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

Selenium is an extremely vital mineral for the human body as 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 plenty of naturally occurring selenium has positive antiviral effects, is essential for successful male and female fertility and reproduction, and also reduces the risk of cancer, autoimmune and thyroid diseases. That’s not all selenium helps either. (1)

How Selenium Benefits Your Body

Selenium is able to play such a protective role in the body because it increases antioxidant capabilities and the quality of blood flow, therefore enhancing the body’s resistance against diseases and stress. Selenium is often praised for its role in antioxidant activity, which lowers free radical damage and inflammation. This is thought to be due to different types of selenoprotein found in selenium.

This means that selenium benefits your body by potentially helping prevent common forms of cancer, fight off viruses, defend against heart disease, and slow down symptoms correlated with other serious conditions like asthma.

Natural food sources that are high in selenium include Brazil nuts, eggs, liver, tuna, cod and sunflower seeds, in addition to poultry and certain types of meat.

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.

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 selenium levels that can lead to a selenium 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. Selenium has a synergistic effect with other antioxidants like vitamin E, enabling the body to fight oxidative stress and defend against cancers like prostate and colon cancer.

Selenium is an essential component of glutathione peroxidase, which is an important enzyme for processes that protect lipids (fats) in cell membranes. Selenium is needed to fight oxidative degradation of cells and protect against mutation and DNA damage that can cause disease. (2)

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. Interventions using selenium treatments at high doses have shown that selenium benefits anti-cancer abilities within the body.

According to studies, selenium is effective at reducing the risk of cancer incidence, cancer-caused mortality and severity of cancers — specifically in the liver, prostate, colorectal and lungs.

Selenium acts like a little mechanic within the body. It goes into the nucleus of cell where the DNA and genome are stored and finds damage. It attaches to protective antioxidants like glutathione and then works to reduce and repair damage done to DNA, which left uncontrolled could lead to cancerous cell mutation and tumor growth.

It does this because selenium has a special job of activating selenoproteins, acting in an enzymic role that helps antioxidants to do their job best. There is evidence that selenium benefits include not only being able cut cancer risk, but also help to slow down existing cancer progression and tumor growth. (3)

Studies have shown that a high dose of 200 milligrams a day of selenium 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 of selenium naturally available. Thus, in certain cases, selenium prevents cancer growth.

3. Boosts Immunity

According to studies, 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, selenium has been shown to also be useful in slowing down the progression of the disease into AIDS.

4. Improves Blood Flow and Lowers Chance of Heart Disease

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

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

To date, selenium concentrations have been inversely associated with coronary heart disease risk in observational studies. However, observational studies can at times lead to misleading evidence and so findings are still inconclusive as to whether selenium will be commonly prescribed for heart disease patients going forward. (4)

5. Regulates Thyroid Function

Research is now showing, through numerous studies, 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.

A deficiency in selenium is correlated with problems within the thyroid and how it synthesizes the proper hormones. Thus, more and more we can see the value of using selenium supplements to treat autoimmune and thyroid disorders.

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. (5)

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. Selenium may be able to increase immunity, lower autoimmune reactions and lower inflammation in these populations.

6. Increases Longevity

Studies have shown just how important this vital mineral is to our health and longevity. If you want to live a long, vibrant life, selenium is definitely a mineral you want to include in your diet.

Selenium has also been studied 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 contribute to a long life.

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 all of these mentioned selenium benefits.

7. Helps Reduce Asthma Symptoms

Observational studies have demonstrated that patients with chronic asthma may have lower levels of selenium. (6) 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. Selenium 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 are reported to 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. (7)

Supplementation and Dosage Recommendations

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.

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

According to studies, additional selenium intake may benefit people with a low status, but at the same time those with adequate to high statuses of selenium in their bodies might be affected adversely, experience toxicity and should not take selenium supplements purposefully for this reason. (8)

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

Best Selenium Foods

Here are the top 12 foods naturally high in trace mineral selenium (percentages based on RDA of 55 mcg/day for adults):

  1. Brazil Nuts — 1 cup: 607 micgroams (1,103 percent DV)
  2. Eggs — 1 medium egg: 146 micrograms (265 percent DV)
  3. Sunflower Seeds — 1 cup: 105 micrograms (190 percent DV)
  4. Liver (from lamb for beef) — 3 ounces: 99 micrograms (180 percent DV)
  5. Rockfish — 3 ounces: 64 micrograms (116 percent DV)
  6. Tuna — 3 ounces: 64 micrograms (116 percent DV)
  7. Herring Fish — 3 ounces: 39 micrograms (71 percent DV)
  8. Chicken Breast — 3 ounces: 33.2 micrograms (58 percent DV)
  9. Salmon — 3 ounces: 31 micrograms (56 percent DV)
  10. Turkey — 3 ounces: 25 micrograms (45 percent DV)
  11. Chia Seeds — 1 ounce: 15.6 micrograms (28 percent DV)
  12. Mushrooms — 1 cup mixed: 15 micrograms (27 percent DV)

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

You can also supplement with selenium in the form of selenomethionine. When taking selenium supplements, adults should take up to 55 micrograms of selenomethionine daily, while pregnant women can take up to 60 micrograms and lactating women can take up to 70 micrograms.

Causes of Selenium Deficiency

Selenium can be found in soil and from food sources. 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 predominately 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. (10)

The content of selenium in soil differs a lot depending on the location. For example, certain studies show concern that parts of Europe and Africa have soil low in selenium levels and the populations living in those areas may be suffering from compromised immunity because of this.

There’s more evidence in other studies showing that a decline in blood selenium concentration is taking place in populations in parts of the U.K. and other European Union countries, which worries health experts. Health authorities worry about several potential health implications that can result due to a selenium deficiency.

One of the main concerns is that these populations will begin showing even higher increased rates of chronic disease that are prevalent in the U.S., such as cancer and heart disease.

Even in food sources, the amount of selenium is largely dependent on soil conditions that the food grew in — therefore even within the same food, levels of selenium can vary widely, and selenium benefits may be found in crops grown in certain locations more so than others.

Suffering from a selenium deficiency is correlated with an increased risk of mortality, poor immune function and cognitive decline, and the deficiency occurs when one or more specific selenoprotein is lacking. (11)

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. According to research, populations in the U.S. of the Eastern Coastal Plain and the Pacific Northwest 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.

Selenium deficiency and iodine deficiency are also considered common in areas affected by Kashin-Beck disease, a chronic bone disorder. (12)

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, a blood test will only show you the amount of selenium you’ve taken recently. Also, 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.

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 could suffer a deficiency that could lead to any serious risks.

Precautions and Side Effects

Taken at normal doses, selenium does not usually have negative side effects.

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.

Again, the toxicity of most forms of selenium is rare and usually only experienced in people who supplement with high levels of selenium. Too high of levels can lead to selenium poisoning or toxicity, and this can potentially be fatal or lead to 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. (13)

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 with any vitamins and minerals, including selenium.

Nutritional care offered by Steven B. Wasserman, a local Chiropractor in Los Alamitos, Dr. Wasserman can provide a consultation to identify the source or cause of your problem and a treatment plan to relieve it. Call us at 562-430-4949 for an appointment.

Final Thoughts

  • Selenium is a trace mineral found naturally in the soil that also appears in certain foods and there are even small amounts in water.
  • Selenium benefits the body in many ways. The top selenium health benefits include defending against oxidative stress, heart disease and cancer; boosting immunity; regulating thyroid function; increasing longevity; reducing asthma symptoms; boosting fertility.
  • Selenium helps the body thanks in large part to its role acting as an antioxidant.
  • The best food sources of selenium include Brazil nuts, eggs, sunflower seeds, liver, rockfish, tuna, herring, chicken breast, salmon, turkey, chia seeds and mushrooms.


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