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Selenium was discovered more than two hundred years ago. Its name comes from the Latin word selēnium which translates as “moon.” Without any doubt, the name did not just come about as a mere poetic metaphor, instead, it captures the essence of the relationship between our overall health and this truly amazing chemical element: just as a night cannot be imagined without the moon and the stars, the normal body function and the life itself cannot exist without selenium.
Selenium is a powerful antioxidant that helps to neutralize the free radicals in our bodies.
Free radicals are unstable atoms that can cause serious harm to your health if their levels in your system are too high. Our bodies are made up of elements (e.g. hydrogen, oxygen, nitrogen, etc.) and each of these elements carries its own electrical charge. When elements combine, their charges form bonds. By contrast, free radicals, which are generated as by-products in the course of ATP (adenosine triphosphate) production by the mitochondria, do not have an electrical charge of their own and as a result, they are unable to form bonds.
Free radicals are considered to be unstable because they have an unpaired electron. In their attempt to become more stable, they seek out and take electrons from other molecules, oftentimes causing damage to those molecules.
Antioxidants like selenium, are molecules that provide the missing electrons to the free radicals without sustaining damage themselves. Antioxidants neutralize free radicals thereby protecting other cells in your body against their harmful effects.
The most famous antioxidant is vitamin E. Other important antioxidants are glutathione (GSH), flavonoids, retinol, and ascorbic acid. In addition, there are also antioxidant enzymes, such as:
- superoxide dismutase;
- glutathione peroxidase;
- glutathione reductase;
- catalases.
Two of these enzymes, glutathione peroxidase, and glutathione reductase, require selenium to achieve the optimal catalytic activity.
Health benefits of selenium
- Provides antioxidant protection. Selenium is incorporated into
- glutathione peroxidase is an enzyme that belongs to the selenoprotein family. The enzyme consists of 4 identical subunits, each containing one selenocysteine atom. The function of the enzyme is to catalyze glutathione synthesis. This antioxidant protects biomembranes and cell structures from oxidative damage (especially fat acids, erythrocytes, hemoglobin, biomembranes, and DNA).
- glutathione reductase prevents the development of oxidative stress.
- thioredoxin reductase regenerates thioredoxin. It is a low molecular weight protein that provides resistance to oxidative stress. Studies on mice demonstrated that higher levels of thioredoxin correlate with better inflammation resistance and longer lifespan.
- Inhibits cell apoptosis.
- Is required for the proper functioning of the thyroid gland.The deiodinases are selenium-containing enzymes that are used to convert the non-active T4 thyroid hormone into T3 – the active form of the thyroid hormone.
- Slows down aging.
- Reduces symptoms of menopause.
- Works in synergy with vitamin E by enhancing its properties.The combination of selenium and vitamin E was shown to be more effective in protecting mitochondria, cytochromes, and biomembranes.
- Selenium supplementation is used in HIV therapy.
A clinical study by Hurwitz et al. (2007) demonstrated that a 200 μg selenium supplementation taken daily for 9 months led to significant suppression of HIV progression. In addition, it also indirectly improved CD4 + T-cell count.
Research: Suppression of Human Immunodeficiency Virus Type 1 Viral Load With Selenium Supplementation
Selenium levels and supplementation
The total amount of selenium in our system should be within the 3 and 200 mg range. The majority of selenium is concentrated in the skeletal muscles — around 47% of the total content of this element, whereas kidneys have only 4% of selenium.
Selenium concentration in blood serum gradually decreases with age, affecting those 60yo and over.
The concentration of selenium in the blood serum that is lower than 85 μg/L leads to a 4-5 fold increase in the risk of developing prostate cancer.
In the past, selenium was considered to be a toxic element. Indeed, selenium poisoning can lead to hair loss, anemia, and blindness. These symptoms were observed in areas where the content of selenium in soil exceeded 1,000 times its average concentration.
Moreover, selenium acts as a functional antagonist to sulfur by replacing it with amino acids (cysteine and methionine) which might disrupt the normal function of the enzymes. This is why it is important not to exceed the Recommended Dietary Allowance (RDA) when supplementing selenium.
According to the World Health Organisation, the RDA for adults (19 years of age and over) is 55 micrograms. However, some experts believe that the adult daily amount should be higher – between 70- 90 mcg. During pregnancy, it is recommended that women should not exceed 60 mcg per day, whilst breastfeeding mothers should not exceed 70 mcg per day.
The best way to supplement selenium is through your diet.
Selenium rich foods
- Brown rice.
- Meat.
- Dairy products.
- Milk.
- Nuts.
- Eggs.
- Fish.
- Asparagus.
- Mushrooms.
- Bread.
- Garlic.
Grains provide up to around 50% of daily selenium intake, while meat, poultry, and fish make up about 35%. Fresh and non-thermally processed vegetables provide about 11% of your daily selenium intake, whilst fruits contribute less than 10%. An important caveat – thermal processing may destroy selenium, so it is best to use as little processing in their preparation as possible.
Selenium yeast, produced by fermenting Saccharomyces Cerevisiae, is the safest form of selenium supplementation. If you have selenium deficiency (see below), adding selenium yeast to your diet will be beneficial to your overall health and especially to the health of the cardiovascular system and the thyroid gland.
12 conditions associated with selenium deficiency
- A study conducted in 2007 among 2,000 Chinese adults over 60 years of age reports a correlation between low selenium levels and cognitive decline.
- Several human studies have suggested that low selenium levels are associated with impaired cognitive function in Alzheimer’s disease.
- Selenium deficiency is associated with a weakened immune system and increased susceptibility to infections.
- Prolonged selenium deficiency might lead to several cardiovascular diseases, including heart failure and heart attacks.
- Selenium deficiency was first associated with Keshan and Kashin-Beck diseases. These diseases were first identified in children and women of reproductive age in the provinces of China where selenium concentration in the soul is low. Keshan disease is a type of cardiomyopathy (a disease of the heart muscle) with high mortality rates. Kashin-Beck disease is a form of osteoarthritis which leads to atrophy and necrosis of cartilages.
- Selenium deficiency is associated with the development of depression and anxiety.
- During pregnancy, selenium deficiency may lead to fetal pathology.
- Selenium deficiency might lead to infertility. Some studies have observed an abnormal sperm morphology in the first two generations of male rats that were fed a diet low on selenium. Furthermore, rats with severe selenium deficiency became infertile.
Research: The influence of selenium on the reproduction of rats
Research: Selenium and male reproduction - Research on cancer prevention suggests that a combination of low selenium and vitamin E levels in the blood might increase the risk of developing certain types of cancer.
Research: Selenium for preventing cancer
Research: The Outcome of Selenium and Vitamin E Cancer Prevention Trial (SELECT) Reveals the Need for Better Understanding of Selenium Biology - Delayed growth and a lung disorder.
- Hemolytic anemia.
- Selenium deficiency may manifest as behavioral and cognitive disorders, depression, and low mood.
How to diagnose a selenium deficiency
Selenium deficiency is tricky to diagnose because there isn’t a single definitive test to determine the levels of selenium in your body.
If your doctor suspects that you might have a selenium deficiency, they may suggest checking the following:
- TSH (thyroid-stimulating hormone) levels. Optimal level: 1 — 1.9 mIU/L.
- A test to check whether the levels of T4 and T3 are lower than normal.
- Selenium concentration in the blood serum and hair.
- Urine test for iodine.
Easy at-home testing for selenium deficiency
If you are concerned that you are not getting enough selenium or experiencing some selenium deficiency symptoms, you can perform a safe and simple test in the comfort of your home.
You will need a bottle of hydrogen peroxide (H2O2) and clean hands. Apply a tiny drop of 3% solution of hydrogen peroxide to your fingertip. If the liquid remains clear, your selenium levels are within the norm
If your selenium concentration is below the norm, the liquid will change in color – it will turn white and you may see some foamy formation.
How to treat selenium deficiency
Treating selenium deficiency requires an increased dietary intake of foods rich in selenium, selenium supplementation, or a combination of the two.
Here we provide some handy tips that will help you to prevent and treat selenium deficiency.
Include plenty of selenium-rich foods into your ration
Selenium-rich foods are the best sources of selenium.
Getting selenium from your diet is the safest way to boost your selenium levels because the other option – the supplements – can cause various side effects.
Selenium Supplements
55 mcg is the standard recommended daily amount.
Remember that it’s always better to talk to a health professional before taking any supplements. They will be able to advise you on the correct dosage.
An overdose of selenium may cause reactions like bad breath, fever, nausea, potential liver complications, and even kidney and heart problems.
The material is based on research:
- Suppression of Human Immunodeficiency Virus Type 1 Viral Load With Selenium Supplementation
- The influence of selenium on the reproduction of rats
- Selenium and male reproduction
- Selenium for preventing cancer
- The Outcome of Selenium and Vitamin E Cancer Prevention Trial (SELECT) Reveals the Need for Better Understanding of Selenium Biology
