13 Evidence-Based Benefits of Selenium

It may seem odd that a mineral that exists only in trace amounts in our food and can only be found in exceedingly small quantities in our body could be so important.

However, it is true. Selenium is this type of nutrient.

You don’t need a great deal, but you do need the proper amount to enjoy good health.

Without the right amount of this critical mineral, you’re the functioning of your heart, thyroid, and nervous system would decline quickly.

You can learn more about this essential nutrient and how you can ensure you that get the proper amount in your diet, by reading our definitive guide to selenium below.

 

Understanding Selenium

Selenium is a trace mineral that enters our food supply through plants or animals that get it from the soil and water which nourishes them.

While we do not need much of this important nutrient, it does play a vital role in our overall health and well-being.

It is an essential role for your immune system, supports cognitive function and enhances both male and female fertility.

Your hormones depend on selenium, as does your DNA.

It can help to protect your cells from infection, as well as the effects of oxidative stress.

Most selenium in your body can be found in your skeletal muscles.

Selenium is primarily found in meat, dairy products, nuts, and whole grains.

While Brazil nuts have the highest concentration of this mineral, other sources include poultry, pork, eggs, sunflower seeds, mushrooms, lentils, kidney beans, and brown rice.

 

How Much Selenium Do I Need?

Having too little or too much of this nutrient can cause health problems.

Therefore, it is essential that you know how much you are consuming.

The medical recommendation is to consume 55 micrograms per day.

This amount maximizes the glutathione activity in the body.

Glutathione is an important antioxidant.

The content of selenium in any given food is dependent on its concentration within the soil where it is found.

Certain areas of the world have higher concentrations, while others have much lower ones.

Therefore, you could be at higher risk, depending on where you live.

The difference between getting too much and not enough selenium is a very narrow window.

Having your blood tested to determine your selenium level, can help you to determine if you are getting what you need from the foods and supplements that you take.

Talk with your doctor about adding this test to your regular check-up labs.

 

Causes and Effects of Too Much or Not Enough Selenium

When your selenium levels are too low, you are likely to experience muscle weakness, fatigue, confusion, or mood disorders.

Low selenium levels contribute to symptoms of heart disease, rheumatoid arthritis, anemia and cancer (1, 2, 3).

If your selenium levels are too low, you are likely not getting enough of this nutrient from the foods you eat.

Other causes of selenium deficiency include Alzheimer’s disease (4), inflammatory bowel disease (5), kidney disease (6), thyroid problems (7), or certain types of specialized diets for rare medical conditions (8).

Certain drugs can also interfere with your ability to absorb selenium into your cells.

If you take corticosteroids, oral contraceptives, or antipsychotics, it is essential that you eat plenty of selenium to avoid a deficiency (9, 10, 11).

If you are getting too much of this nutrient,  you can also suffer some adverse effects.

Taking selenium supplements or eating a diet rich in concentrated sources of selenium can result in toxic levels of the mineral in your body (12).

Excess selenium can also have significant effects on your body.

If your levels are too high, you may experience vomiting, nausea, diarrhea, other stomach problems, a rash, an elevated heart rate, or low blood pressure (13).

At toxic levels, selenium can cause muscle spasms, delirium, tremors, confusion and even coma (14).

These symptoms can persist long after you discontinue supplementation (15).

If you have prolonged exposure to excessive levels of selenium, you are at an increased risk for developing Type 2 diabetes.

This is more likely to occur in men who take selenium supplements and also have a diet high in this mineral (16).

Therefore, if you do not have a selenium deficiency, you should avoid taking this supplement.

For men with non-metastatic prostate cancer, you should avoid taking selenium supplements.

This is because it can increase your risk of dying from this disease.

While evidence on this phenomenon is limited, some results indicate a link, and therefore, supplementation should be avoided, until the risks are more fully understood (17).

Men who take too much selenium may also experience low levels of T3 thyroid hormone, which indicates that the thyroid is not functioning correctly (18).

Hyper- or hypothyroidism are both severe conditions with severe consequences and should not be overlooked.

Pregnant women should avoid taking too much selenium since fetal exposure to high amounts of this mineral has been linked to an increased risk for developing Attention-Deficit/Hyperactivity Disorder or ADHD (19).

More research is needed in this area to understand this relationship.

Finally, excess amounts of selenium are also linked to high levels of lipids, including HDL, LDL and total cholesterol (20).

 

Selenium’s Health Benefits

Selenium has numerous health benefits. Not getting enough selenium can cause severe problems.

However, when you eat a diet that includes healthy sources of this trace mineral, you can enjoy many health advantages.

We will discuss what medical research has learned about the importance of selenium to maintaining optimal health and well-being.

 

Reduces Inflammation

One of the reasons why our body needs selenium is that it is responsible for forming selenoproteins which play critical roles in producing and using antioxidants which are used to fight disease.

By boosting the production of antioxidants, this mineral can reduce inflammation, protect against autoimmune disorders and promote better immunity (21).

NF-κB is a complex of proteins which control DNA transcription, cytokine production and cell survival in the body.

Cytokines produce the inflammatory response, and selenium helps to block the activation of NF-κB, thereby reducing inflammation.

When you have fewer inflammatory markers, you have less inflammation (22).

 

Promotes Thyroid Function and Health

One of the selenium’s most vital roles is its effect on thyroid function.

This mineral is most concentrated in your thyroid gland.

As a result, even tiny differences in your levels of this nutrient make a significant difference in how well your thyroid is working.

Low levels of selenium are linked to thyroid disorders.

When your thyroid is underactive, it results in hypothyroidism which can be caused by several factors.

Hashimoto’s Thyroiditis and Grave’s disease are two thyroid disorders that result from under activity of this vital gland.

In both disorders, selenium deficiency can play a role in disease progression and severity (23, 24).

Taking supplemental selenium has been shown to help people with these types of thyroid conditions.

Pregnant women can also experience thyroid problems.

One group of researchers found that subclinical hypothyroidism can be treated and reversed with supplemental selenium (25).

 

Has Neuroprotective Benefits

Selenium is a mineral that works together with many other essential nutrients to support your health.

This includes fatty acids that work together to protect your brain.

The beneficial effects of fatty acids, combined with selenium, have the ability to protect your nervous system from the effects of aging, including from Alzheimer’s disease.

Since fish is an excellent source of selenium, those who eat more of this food are more likely to have higher serum levels of this mineral.

Fish is also an excellent source of omega-3s.

Studies examining elderly people who eat more fish show that they are less likely to have cognitive decline, while also having higher selenium levels (26).

When you are deficient in this nutrient, you are more likely to have memory issues and trouble reasoning (27).

 

Can Help Alleviate Sleep Disorders

Our bodies have a natural internal clock that tells us our optimal times for sleeping, waking and other important activities.

Your circadian rhythm dictates your sleep/wake cycle, and those with well-regulated cycles are less likely to suffer from insomnia and other sleep disturbances.

A particular amino acid found in selenium, methyl selenocysteine, plays a significant role in your circadian rhythm.

It helps to express the right genes that tell your body to reset your cycle each night at midnight.

Eating foods rich in selenium can help keep your sleep well-regulated and restful (28).

 

Enhances Immunity

When your selenium levels are low, your immune system can struggle to function properly.

Immune cells known as lymphocytes are more active and work more efficiently at destroying pathogens and other invaders when you have sufficient levels of selenium in your cells (29).

 

Protects Against Viral Infections

When you lack an adequate amount of this important trace mineral, you may become vulnerable to certain viral infections which, if left untreated, can become dangerous or even deadly.

When you have enough selenium in your immune cells, you can produce the antibodies necessary for fighting these pathogens (30).

One virus, in particular, is very responsive to selenium levels.

HIV, the virus that causes AIDS, can lead to a selenium deficiency.

When your levels of this critical nutrient are high, the virus is less likely to progress or cause death overtime (31).

Those with HIV should consider taking a selenium supplement to keep their levels high because, when used in combination with conventional HIV treatments, this supplement can inhibit the replication of this deadly virus and keep you healthier longer (32).

 

Improves Reproductive Health

Both men and women need selenium in their diets to maintain reproductive health and to improve their fertility.

Women always require selenium but especially during the first trimester of pregnancy.

There has been a correlation noted between miscarriages in the first three months or recurrent miscarriages with lower levels of selenium (33).

Pregnant women should include rich sources of this mineral in their diet.

Men also benefit from adequate nutrition.

One study noted that selenium supplements helped to increase the fertility of some men, by improving sperm motility (34).

Within this study, those men in the placebo group had no successful paternity outcomes, but 11 percent of the men in the treatment group did.

Animal studies indicate that this mineral improves testosterone levels in males (35).

 

Reduces Airway Inflammation

Asthma is chronic inflammation of the airways and air sacs found in your lungs.

When these spaces become inflamed and irritated, they become narrow and result in coughing, wheezing, shortness of breath and other symptoms that can make it difficult to breathe.

The more oxidative stress and inflammation in your body, the more likely you are to have an asthma attack if you have this condition.

By lowering inflammation and combating oxidative stress, selenium can help to control your asthma and prevent flareups.

There is some evidence to suggest that those with asthma may also have lower levels of selenium (36), which means boosting this nutrient in your system could help to alleviate your asthma symptoms.

Research studies, which have tested this theory, have found that patients taking selenium supplements relied less on conventional corticosteroids to control their asthma symptoms (37).

 

Enhances Mood

By supporting healthy cell function and growth within your nervous system, this mineral may also play a key role in your mental health and mood.

Having just a slightly low selenium level can impair mood and result in anxiety, because of a dip in the production of neurotransmitters that help regulate your emotions.

Those with depression and anxiety are more likely to have lower levels of selenium.

These deficiencies can lead to confusion and fatigue.

Taking supplements can help to reduce these negative effects in just a few weeks (38).

This includes helping the elderly cope with depression and anxiety (39).

 

Supports Heart Health

Your heart also significantly benefits from the antioxidant powers of selenium.

By enhancing the production of glutathione and lowering the impact of oxidative stress, selenium reduces the formation of heart-damaging plaques (40).

When your levels of this nutrient are low, your blood vessels are less flexible, and platelets in your blood are more likely to clump and create new plaque.

Over time, this degrades your heart’s health and can lead to heart disease (41).

Some studies indicate that a low selenium level can increase your risk of developing and even dying from heart disease (42), while other studies show that this deficiency can increase your chances of having a stroke or heart attack (43).

While smaller studies do not always support these claims, there needs to be more research using high-quality methodologies to determine any causal link.

 

Promotes Longer Life

Selenium, by fighting oxidative stress and lowering inflammation, can help to promote your overall health and allow you to live longer.

As a part of a healthy diet that is rich in antioxidants, this mineral plays a crucial role in treating and preventing many different health conditions that can shorten your life and decrease your enjoyment of the time you are alive.

 

Could Help with DNA Repair

DNA is the basic building block of all life.

It is the genetic code that determines your traits, your health, and many other things.

Sometimes, you can become exposed to various environmental triggers that can alter or engage certain aspects of your genetic code and lead to DNA damage (44).

The more DNA is damaged by chemicals, aging, UV radiation,  and other pollutants, the more likely you are to suffer from a chronic illness.

Selenium could play a significant role in protecting your DNA from damage and keeping you healthier over time.

When you have sufficient levels of selenium in your system, your DNA is more likely to activate repair responses when faced with hazards, which means this mineral protects your DNA from long-term damage (45, 46).

 

Could Help Prevent Cancer

While there is some conflicting evidence, selenium could play a vital role in the prevention and treatment of certain types of cancers.

Here is what we know so far.

There have been many studies over the past 40 years that indicate that selenium can reduce the risk of death by cancer.

In one study, which covered over 25 countries, it was found that those who ate more selenium, were less likely to die from cancer (47).

When you compare areas with high selenium concentrations in their soil to regions with a low density, there is a significant difference in the cancer death rates.

Several other studies over this period confirmed this same risk or correlation, with low selenium being linked to increased cancer rates, as well as higher death rates from this disease (48).

More recent research also found that those who took selenium supplements had a lower risk for lung, prostate and colorectal cancers (49).

The effectiveness of selenium in preventing or treating cancer is improved, when it is added to a supplement of Milk Thistle (50).

This reduces the progression and regression rates of prostate cancer.

While it is difficult to study the phenomenon of cancer prevention, these studies are promising and warrant further investigation.

Other factors certainly influence this disease, so understanding how selenium could inhibit cancer growth is crucial for future studies.

A more rigorous methodology and larger sample sizes would help to eliminate the questions that still linger regarding selenium’s efficacy.

A metanalysis of this topic has revealed problems in these areas that may not provide an accurate picture of this mineral’s real impact on cancer.

When we examine both animal and cellular studies, there is a reason to believe that researchers are on the right path regarding the theory of selenium being linked to cancer growth.

Cell studies show that selenium can destroy or degrade cancer cells while inhibiting their reproduction (51).

Since it offers protection from DNA damage, which plays a role in the spread of cancer, it also has protective benefits.

Research also tells us that having more selenium in your system can help reduce the adverse effects of cancer treatments, especially radiation therapy (52).

Taking supplements can improve your quality of life and reduce the stomach upset and other digestive problems often associated with certain cancers, as well as cancer treatments.

 

Precautions and Interactions

When you follow supplement dosage guidelines, this nutrient is safe to take and does not have any adverse side effects.

If you take too much, however, you can suffer from nausea, fever and even liver or kidney complications.

Heart problems are also possible with toxic doses.

Selenium toxicity or poisoning is rare but occurs when someone takes too many supplements.

Excessive doses can cause a heart attack or cause your lungs to struggle to breathe.

If you take any medications or supplements, you should talk to your doctor before taking selenium.

Statins, oral contraceptives, corticosteroids, and antacids can be affected by this nutritional supplement.

Those undergoing chemotherapy should also talk with their doctor before taking selenium.

Always share with your doctor your full medical history and list of medications, when considering any nutritional supplements.

 

Conclusion

Selenium is a trace mineral that can be found in soil and water.

It makes its way into the various foods that you eat.

This mineral is located in the cells in your body and must be replenished by your dietary intake since you cannot produce it yourself.

Foods high in selenium include poultry, fish, dairy products, nuts, legumes, and mushrooms.

Some fruits and vegetables may also have some selenium.

Areas with nutrient-depleted soil will not produce foods that are high in this mineral.

Selenium has many benefits for your overall health and well-being.

It is necessary for muscle contraction, neural health, thyroid function, and immunity.

Your heart, reproductive organs, lungs, and bones all benefit from having the proper levels of selenium in your cells.

While the evidence may appear somewhat mixed, there is a support that a healthy diet contains many foods that are high in selenium, can support your overall health and wellness.

More research will determine whether selenium supplementation is necessary or useful for achieving the same goals that natural foods can accomplish.

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The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.

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