Selenium: Benefits To Health

What Is Selenium?

Of all the known antioxidants, the mineral selenium is one that is not very well known or talked about when it comes to health benefits.

Selenium is essential for heart health, immune system functioning and as a general body antioxidant.

Organic & Inorganic Selenium

The two major forms of selenium, as found naturally in cells, are selenocysteine and selenomethionine. These are basically seleno bonded amino acids or seleno-amino acids, that form the bigger selenoproteins. In your food, selenium is organically bound like this.

Selenoproteins, made from seleno-amino acid units, form from the mineral uptake of selenium. These selenoproteins have key functions within the body. Some selenoproteins have multiple units of the seleno-amino acids, multiplying their effects.

Inorganic elemental, or mineral selenium like selenite, as found in the soil can come from volcanic activity as part of the soil selenium cycle. Hydrothermal activity also affects selenium soil concentration in groundwater.

Selenium Toxicity

Selenium is absorbed in the small intestine and the recommended daily allowance for selenium is around 200 micrograms a day.

The absorption of this from this intake of selenium is beneficial for its health effects, not all dietary selenium will be absorbed.

There is a narrow toxicity range for selenium, meaning you can overdose on selenium easily. However, this amount is well above a usual selenium intake amount.

Toxicity is thought to start at about 100 micrograms per litre of blood, with total blood volume being about 5 litres. Other studies quote selenium consumption in-excess of 400 micrograms per day.

Low Selenium Effects on Health

Conversely, low body selenium levels are linked to poor immune function and cognitive declines. These are major health disadvantages of a selenium poor diet.

Lowered selenium levels can also result in muscular degeneration and selenium is thought to prevent certain types of cancers developing.

Other diseases where selenium is implicated include, liver necrosis, kidney degeneration, lack of hair growth, premature abortion and anaemia.

In terms of chronic inflammatory diseases, selenium supplementation has been used successfully in reducing pain symptoms of arthritis.

Let’s go into more detail on how selenium functions in the body and the health benefits of selenium.

Health Benefits of Selenium

anti-Cancer Activity

Above all of it is benefits to our health, selenium is a really potent antioxidant.

As an antioxidant, selenium binds to reactive oxygen molecules very easily because of their loose electrons in their structure. The structure of selenium means that it packs a punch as an antioxidant, being capable if some serious oxidative recovery.

Selenium is thought to have anti-cancer effects through antioxidant activities in cell membranes.

In countries where there were higher intakes of selenium in the general population, there were visible reductions in cancer rates such as intestinal cancer.

Interestingly, selenium is thought to display anti-cancer activity versus various chemical aggressors.

This is quite important for our health considering the harsh and unnatural environments that people are exposing themselves to every day.

Cell membranes are full of attached proteins. This might be why selenium activity is high in cell membranes.

Glutathione Peroxidase: DNA Damage Prevention

As mentioned, selenium incorporates itself into cysteine to form the seleno-amino acid selenocysteine that is seen in the selenoproteins. In selenoproteins of the body, selenium forms a crucial part of many different enzymes and processes.

Glutathione peroxidase is a key enzyme that the body produces, a lot of selenium goes directly into this enzyme. In the enzyme complex selenocysteine is the most prevalent form.

Glutathione peroxidase is an example of a key selenoprotein, or protein containing selenium. This enzyme removes harmful products of cell activity such as cell damaging peroxides.

Through these actions, glutathione peroxidase protects DNA from charged or radical oxygen damage and cancerous mutation.

It’s not just this particular protein or enzyme that selenium associates with. Selenium also incorporates into thioredoxin reductase, as another defence against radical damage and stress.

As mentioned, cell damage, stress and DNA damage are all directly implicated in various cancers. Through reducing these outcomes, selenium assists with cancer prevention.

Specific cancers to the mammary glands, induced by certain viruses, are thought to be prevented through adequate selenium intake in one’s diet. This might be because of membrane specific antioxidant effects.

Supplementation with selenium will ensure adequate levels of this antioxidant in the body and the health benefits of that.

Selenium And Fertility

The health benefits of selenium on fertility, especially sperm count, are unprecedented.

It is widely known that selenium is beneficial for sperm production and fertility. Animal studies have shown testicular degeneration in low selenium states.

Selenium has a positive impact on sperm motility, a key factor for fertilization. There is also a particular protein that has a strong role in sperm production that needs selenium to initiate.

There is also a suggestion that selenium affects the number of healthy to defective sperm cells. Some of this could be due to oxidative damage that occurs to sperm in the testis.

In female animals, selenium is associated with pre-mature abortion and ovarial dysfunction.

Immune System Booster

Higher uptake of selenium or selenium supplements seem to be associated with antiviral responses.

Some studies have shown that selenium counters viral progression of HIV to AIDS. This highlights how important selenium is to immune system functioning.

Selenium supplementation has an immune regulation effect, improving the proliferation of certain immune cells. This effect was seen with fairly normal selenium levels as well. It is thought that the antioxidant and anti-inflammatory effects of selenium help T cell proliferation.

When there is a deficiency in selenium the opposite happens. You see more autoreactive T cells and antibody production increases.

Also, the antioxidant activities of selenium seem to protect immune cells from the oxidative damage that happens when antigens or harmful substances are detected in the blood.

Selenium directly regulates the ability of immune cells to kill harmful organisms, influencing the entire immune response.

Selenoproteins play a massive role in the antioxidant firefighting duties to calm the inflammation at the source of infections, or resulting from infections.

There could be health benefits to your immune system functioning from supplemental selenium intake.

Thyroid Gland Health

Selenium benefits the health of the thyroid gland.

Selenium provides the perfect supporting partner to iodine for thyroid health. Many people find themselves equally deficient in both selenium and iodine.

Accumulated lack of dietary selenium and partnering iodine results in cretinism. This is a disease where cognitive function is impaired, along with growth. Selenium has a direct regulatory role in DNA synthesis.

This means that selenium is implicated in both normal growth and higher brain functioning.

Selenium deficiency has also been linked to the progression of certain cognitive diseases that progress with old age, including Alzheimer’s and Parkinsons disease.

Selenium: Effect on Thyroid Gland Inflammation

Selenoproteins are involved in protecting the thyroid gland from reactive oxygen species damage, especially those coming from metabolic reactions that make thyroid hormones. This largely is due to the actions of glutathione peroxidase, a previously mentioned selenoprotein.

The actions of glutathione peroxidase in the thyroid might be preventative for thyroid cancer.

Glutathione peroxidase reduces dangerous superoxides from forming, as well as inflammatory cytokine expression specifically from immune cells.

Use of selenium in various thyroid immune disorders has improved certain symptoms and quality of life. This may be due to the anti-inflammatory or immunoregulatory actions of selenium on balancing the expression of cytokines.

One study found that the thyroid gland was no longer so enlarged with selenium sufficiency.

Selenium directly catalyses the formation of thyroid hormone, being involved in several phases of thyroid hormone synthesis. Because of this selenium is thought to be implicated in mood expression or sensation.

Here it seems like selenium supplementation might have health benefits, particularly for the thyroid gland.

Heart And Cardiovascular Function

There are a couple of heart diseases where selenium deficiency is a central factor to their escalation.

When selenium levels are reduced, the heart switches into a disease state where it finds it more and more difficult to pump blood around the body. This is called Keshan’s disease.

This is quite dangerous for the heart, putting strain on the circulatory system. Where there are incredibly low levels of selenium for long enough in the body, one can die from this particular heart disease. Essentially the heart fails.

Thyroid hormones are important regulators of heart function and selenium clearly plays a role there. There are various factors involved in the development of this disease including oxidative stresses.

Oxidative Damage of the heart Muscle

It is thought that without crucial seleno-amino acids, like selenocysteine, that the heart completely arrests from inflammatory and oxidative stress build up.

This might be because the heart muscle is constantly contracting and needs to offset the build-up of oxidative damage.

Follow up studies on natural nuclear miRNA expression, a cell activity-transforming nucleotide or genetic material, in selenium deficiency showed upregulated genetic pathways for heart cell death.

This might mean like when you haven’t had enough to eat for a long time, the heart slowly dies off. All the current evidence points towards that conclusion.

While not fully understood yet, the effects of selenium deficiency are a focal point.

Current evidence also suggests that higher selenium levels reduce risk of cardiovascular disease. While supplementing with selenium after a heart injury seems to have some beneficial effect.

This would strongly suggest selenium has a massive role in heart health.

Conclusions

Selenium is vital for many processes in the body due to its antioxidant capabilities.

Forming a key part of specific proteins called selenoproteins, selenium plays a role in cancer prevention, thyroid health, regulation of normal immune system responses, heart functioning and also fertility.

The selenoprotein enzyme glutathione peroxidase has a massive role in all of these functions, particularly as an antioxidant.

In relation to the thyroid, selenium maintains optimal thyroid functioning and metabolism. Through various actions selenium was seen to reduce thyroid enlargement  or inflammation.

Selenium has an independent role in cretinism prevention within the thyroid too. Selenium is a regulator of DNA production at the cellular level.

While selenium is essential for life, the toxicity range is something to be aware of but not a major concern. 

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