Selenium got spotlight a decades ago when researchers got to know mysterious type of heart disease in Asia was caused due to deficiency of selenium. Selenium is a metalloid element having atomic number 34. It is an element which determines normal functioning of organism with antioxidant properties and protect organism against the free radicals damage and carcinogenic factors. This element fulfills essential physiologic function but have fine lines between concentrations which has beneficial effects on organism. It is included in metabolism of hydrogen peroxide as well as lipid hydroperoxides. It comprises an integral part of enzymes such as deiodinase iodothyronine, glutathione peroxidase and thioredoxin reductase which protects cells from harmful effects of free radicals which form during oxidation process.
This nonmetal have properties which are intermediate between elements below and above in periodic table, tellurium and sulfur and have similarities to arsenic. Rarely, it occurs in elemental state and as pure ore compounds in Earth’s crust. Literally, selenium was discovered by Jons Jacob Berzelius in 1817 who noted down similarity of new element to previously discovered tellurium. Selenium is found in metal sulfide ores which replaces sulfur partially. It is created as a byproduct in refining of these ores during production. The rare minerals are known which is selenate or pure selenide compounds. Selenium is used for pigments and glassmaking. It is a semiconductor and used in photocells.
What Foods Provide Selenium?
Like many of the trace minerals, the quantity of selenium in natural food sources is often a reflection of the soil content in which plants were grown and the animals grazed. Animal products, including seafood, seem to be better sources of dietary selenium than plants.
| Food name | Weight (g) | Selenium (µg) | DV% |
| Brazilnuts | 133 | 2549 | 4634% |
| Turkey | 863 | 264 | 480% |
| Durum wheat | 192 | 171 | 310% |
| Semolina | 167 | 149 | 270% |
| Tuna fish | 146 | 111 | 201% |
| Lobster | 150 | 95 | 172% |
| Octopus | 85 | 76.2 | 138% |
| Oyster | 85 | 54.1 | 98% |
| Sesame seeds | 144 | 49.5 | 90% |
| Mackerel fish | 88 | 45.4 | 82% |
| Pork | 135 | 45.4 | 82% |
| Wheat bran | 58 | 45 | 81% |
| Couscous | 157 | 43.2 | 78% |
| Oat bran | 94 | 42.5 | 77% |
| Egg | 136 | 41.9 | 76% |
| Flatfish | 127 | 41.4 | 75% |
| Malt syrup | 332 | 40.8 | 74% |
| Salmon | 85 | 39.8 | 72% |
| Swiss cheese | 132 | 39.6 | 72% |
| Mozzarella cheese | 132 | 36.4 | 66% |
What Are Current Recommendations for Selenium Intake?
The RDA for selenium is the same for adult men and women at 55 micrograms daily. However during pregnancy and lactation the RDA increases to 60 and 70 micrograms daily.
Health Benefits of Selenium
Adequate presence of selenium in the body offers these health benefits:
- Lowers oxidative stress
Selenium is helpful in combating the aging process and assist immune system by lowering free radical damage. It has synergistic effect with antioxidants such as Vitamin E that enables body to counteract oxidative stress and defend cancers such as colon and prostate cancer. Being a vital component of glutathione peroxidase, selenium is essential for processes which protect lipid in cell membranes. It is essential to counteract oxidative degradation of cells and protect against mutation or DNA damage which causes disease.
- Cancer prevention
Selenium is found to be helpful for those having weak immune system or with a history of having cancer in family. When selenium is used as a treatment at high doses, it shows its anti-cancer ability in the body. Effectively selenium lowers the chances of cancer incidence, cancer severity such as colorectal, prostate, liver and lungs. Selenium operate as a little mechanic in the body which goes into nucleus of cell where genome and DNA are stores and discover damage. It connects to protective antioxidants such as glutathione and works to lower and repair damage made to DNA which when left uncontrolled result to cancerous cell mutation or tumor growth.
- Enhance immune system
Studies have shown that selenium is essential for functioning of immune system and is a key nutrient to counteract development of viruses such as HIV. With contracted HIV, selenium is found to be helpful for slowing down progression of disease into AIDS.
- Prevent cardiovascular problems
Low content of selenium is related with growing chances of cardiovascular diseases. Increase of foods rich in selenium or selenium supplements helps in preventing coronary heart disease. Selenium is believed to be beneficial for heart health and counteract inflammation, reduce free radical oxidative stress and increase blood flow. Selenium is inversely related with coronary heart disease.
- Thyroid health
Various studies have shown the link between deficiency of selenium and thyroid metabolism. It acts as a catalyst for producing active thyroid hormones. Thyroid gland is the one which control various vital everyday body functions such as sleep, appetite, weight, temperature and energy. The improper thyroid function results in irritability, fatigue, muscle weakness, trouble sleeping, weight gain or loss and other reactions. Selenium deficiency is associated within problems of thyroid and it synthesizes proper hormones. The supplements of selenium are found to be helpful in treating thyroid and autoimmune disorders. It protects thyroid health and regulates production of reactive oxygen within gland and also prevent from antibodies which create thyroid disease. The investigation is being carried out to see if it is helpful for patients with Grave’s disease, Hashimoto’s disease and in pregnant women with anti-TPO antibodies. It enhances immunity, lower inflammation and reduces autoimmune reactions.
- Increase longevity
Study shows that selenium is essential to maintain longevity and health. This mineral helps the one to get long and vibrant life. It has been studied for treating various conditions such as arthritis, asthma, heart disease and thyroid disorder. People become more prone to these conditions as the person ages so intake of selenium defends body and provides long life. It is a trace mineral which is required in small amounts. It has vital role in various body functions
- Lower symptoms of asthma
Studies show that patients having chronic asthma have low content of selenium. When asthma patients took supplements of selenium, they experienced low asthma symptoms. The supplements of selenium are useful as add-on treatment to medication for patients having chronic asthma. Still the research needs to be carried out to evaluate full effect of selenium on lung function.
- Promotes fertility
Selenium is essential for proper sperm motility and promotes blood flow. Selenium is assimilated in sperm mitochondria capsule and affects behavior or function of sperm as it moves through vagina canal. It shows that both high and low sperm selenium concentrations have negative influence on number of sperm. Thus one should aim to meet recommendation as it is required for fertility. Studies show that selenium lowers the chances of miscarriage but still research should be carried out to infertility in men than in women with selenium supplementation.
- Acts as detoxifier
Various ways are found to detoxify body which is required as the body build up toxins form diet which people consume normally which especially consists of processed foods. The body should be detoxified in order to keep organs and liver healthy. One should consume foods which combat pollutants such as heavy metals. The body undergoes through environmental damage so it is essential to add selenium supplements or diet rich in minerals for liver detoxification.
- Healthy skin
The healthy diet shows on face and processed foods or lack of water could result to acne breakouts. Then one eventually spends lavishly on treatment and skin care products. Yet treating skin with harsh chemicals is not a good idea as the skin is delicate naturally. But skin should be nourishing in a natural way rather than using chemical filled substances. Due to this beauty experts put emphasis on consumption of healthy diet. Healthy diet refers to consumption of all vitamins and minerals required for youthful skin. Selenium is helpful in this case as mineral is found in every food which beauticians suggest.
What Happens If We Get Too Little Selenium?
Mild selenium deficiency can reduce antioxidant capabilities as well as compromise efficient thyroid hormone action. Meanwhile, extreme selenium deficiency has been determined to be the cause of Keshan disease. The major medical problem associated with Keshan disease is an enlargement and abnormal functioning of the heart and eventual heart failure. The disease was observed in discrete regions of Asia where the selenium content of the soil is extremely low. The people within this region relied exclusively on crops and livestock grown in that area for food yet both of these food sources had very low selenium contents. Keshan disease is preventable with selenium supplementation.
Can We Get Too Much Selenium?
Selenium intakes greater than 750 micrograms/day over time can produce toxic alterations such as hair and nail loss, fatigue, nausea and vomiting, and a hindrance of proper protein manufacturing. Selenium toxicity is rare and seems likely only with excessive supplementation.
Side effects
- One should seek for medical help when experienced sings of allergic reactions such as difficult breathing, hives, swelling of lips, face, throat and tongue.
- High doses of selenium when used for longer time period causes harmful side effects
- Seek for medical attention when experienced nausea, lack of energy, vomiting, feeling irritable or very tired, hair loss, brittle or painful fingernails, mild rash, white streaks on the nails, tremors, muscle tenderness, feeling light-headed, metallic taste, flushing, strong body odor, bad breath, easy bruising and bleeding.
Other facts
- The term selenium is derived from Greek word “selene” which refers moon and also Greek goddess of moon.
- Selenium has an element symbol as Se.
- In 1817, it was discovered by Johan Gottlieb Gahn and Jons Jakob Berzelius.
- Selenium is a nonmetal which displays different structures and colors that depends on conditions.
- Selenium is required for proper nutrition in organisms such as humans and other animals.
- It is rare to find selenium in natural elemental state.
- In nature, selenium has six isotopes but only five are stable.
- In the world, about 2000 tons of selenium is extracted annually.
References:
https://en.wikipedia.org/wiki/Selenium
https://www.everydayhealth.com/drugs/selenium
https://www.thoughtco.com/interesting-selenium-facts-609110
http://www.softschools.com/facts/periodic_table/selenium_facts/211/