Selenium Overview, Health Benefits, Source Food, Deficiency, Side effects
Selenium is a mineral found in the soil. Selenium naturally appears in water and some foods. The mineral selenium performs many important and essential roles in the human body. One of the major bio-chemical functions of this chemical include anti-oxidation actions at the cellular level, taking part in several enzyme systems, and as a vital component in the maintenance of muscle cell and red blood cell integrity, it also plays a role in the synthesis of nucleic acids - DNA and RNA. This mineral is vital in the detoxification of poisonous metals from the body, it plays a role in cellular respiration and energy transfer reactions, it is also a major player in the production of sperm cells, it plays a part in fetal development and growth, it is also essential in the maintenance of the integrity of keratinous tissues - including the skin, the hair and the nails, it maintains pancreatic functioning, it is involved in the synthesis of antibodies as well as in the production of compounds called the ubiquinones - these chemicals are believed to help in protecting the body against infectious diseases and malignancies, aiding the body deal with inflammatory diseases, psoriasis, chronic heart disease and high blood pressure disorders, viral infections.
Why do people take selenium?
Selenium has attracted attention because of its antioxidant properties. Antioxidants protect cells from damage. There is some evidence that selenium supplements may reduce the odds of prostate cancer. Selenium does not seem to affect the risk of colorectal or lung cancer. But beware: selenium also seems to increase the risk of non- melanoma skin cancer.
Among healthy people in the U.S., selenium deficiencies are uncommon. But some health conditions -- such as HIV, Crohn's disease, and others -- are associated with low selenium levels. People who are fed intravenously are also at risk for low selenium. Doctors sometimes suggest that people with these conditions use selenium supplements.
Deficiency Causes and Symptoms of Selenium
Selenium can be found in soil and from food sources. There are actually 4 naturally occurring types of the trace mineral selenium. The 4 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, selenium 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.
Many other biological processes also involve the mineral selenium as part of their bio-chemical pathways, the distribution of this mineral is however, not uniform and hence it is not a surprise that at least forty animal species suffer some form of disorders attributable to a deficiency of selenium. Selenium is routinely included as a supplement in most animal feeds in order to prevent the occurrence of these diseases in farm animals. The occurrence of physical symptoms such as calcification and degeneration of muscle tissues and lesion formation in the blood vessels of the heart is observed in farm animals deficient in the mineral selenium. A deficiency of selenium also causes the liver tissues to lose their ability to actively take up oxygen and they die as a result. A selenium deficiency also affects the integrity of the cell membranes and severely compromises the cellular structure - as a result the cellular membranes can turn "leaky ", the cellular fluid that leaks from the compromised cells and membranes accumulates in the tissues. One consequence of this cellular leakage is that many of the intracellular enzymes leak into the blood stream. Male infertility can often be induced due to selenium deficiency; the absence of this mineral in the tissues induces testicular degeneration and results in the active impairment of sperm motility as the first sign of impending infertility. Selenium deficiency can also induce infertility in females, this occurs by way of fetal death and resorption of tissues.
The metabolism of the vitamin E actually increases in a human body that has a selenium deficiency; a direct consequence of this situation is an increase in the metabolic requirement for the vitamin in the body of the affected person. The damaging effects of ozone on the pulmonary system are increased in a person suffering from selenium deficiency. Selenium deficiency has also been implicated in oxidative damage to the lungs and eyes of premature infants given oxygen therapy since premature infants generally have lower levels of the mineral selenium then comparable normal term infants of the age groups.
The levels of the enzyme glutathione peroxidase and its bio-chemical activity in the body are severely affected by a deficiency of the mineral selenium. Hereditary factors were thought to be responsible for this reduced enzymatic performance at one time - recent research has connected this lowering of enzyme action with low levels of the mineral.
Suffering from a selenium deficiency is correlated with an increased risk of mortality, poor immune function, and cognitive decline.
Gross deficiencies of selenium are quite rare in western countries, even though most people probably do not take sufficient selenium in the diet. Selenium is deficient in the soils of some areas and a risk of developing a deficiency of selenium exists in people who mainly eat foods grown primarily on selenium deficient soils. Selenium deficiency has also been reported to be evident in individuals affected by AIDS. There is also a clear association between heart disease and depleted levels of selenium according to the evidence from limited research.
Good food sources of Selenium
Selenium content of food is largely dependent on location and soil conditions, which vary widely. The average daily intake in the U.S. is 125 mcg per day. Populations of the Eastern Coastal Plain and the Pacific Northwest have the lowest selenium levels, averaging between 60 to 90 mcg per day, which is still considered to be adequate intake.
Food sources that have the most abundant amounts of selenium are nuts such as Brazil nuts, all organ meats, all seafood, cereals and whole grains as well as brewer's yeast. Selenium is also found in high amounts in special yeasts that are grown on a medium rich in selenium. Selenium in supplemental amounts is supplied by these yeasts - these are normally available in tablet form alone. Supplemental selenium is also available in other forms such as sodium selenite. The most efficiently absorbed source of selenium is yeast with organically bound selenium.
Good natural food sources of selenium include:
- Nuts, like Brazil nuts and walnuts
- Many fresh and saltwater fish, like tuna, cod, red snapper, and herring
- Beef and poultry
Whole foods are the best sources of selenium. The mineral may be destroyed during processing.
Health benefits of Selenium
Health benefits of Selenium: Helps 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, colo-rectal and lungs.
Low level of selenium in the body may increase the risk of prostate cancer. It is known that selenium can enhance the antioxidant capacity of the body, and it may help to reduce cell damage that is associated with prostate cancer. Those who are affected by selenium deficiency can become less vulnerable to prostate cancer if they increase their intake of selenium.
Health benefits of Selenium: Prevents Keshan Disease
Keshan disease is a fatal condition that is characterized by inflammation of heart muscles, and the problem is mostly found in areas in China where the soil has low levels of selenium. Those who suffer from this disease will become more susceptible to heart disease, cancer, high blood pressure and strokes. Since selenium assists in the functioning of the thyroid gland and it offers protection against heart conditions, taking selenium supplements can help prevent the disease.
Health benefits of Selenium: Reduces Mal-Absorption
Mal-absorption refers to abnormal absorption of nutrients in the gastrointestinal tract. It is found mostly in children who suffer from selenium deficiency. Selenium supplements can help improve digestion and reduce the problem of mal-absorption.
Health benefits of Selenium: Improves Blood Flow & 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.
Health benefits of Selenium: Lowers Risk of Cardiomyopathy
Cardiomyopathy is another disease that causes the muscles of the heart to deteriorate. Low levels of selenium result in the lack of antioxidants in the heart and the muscles, and it's one of the factors that contribute to the development of cardiomyopathy.
Health benefits of Selenium: 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.
Health benefits of Selenium: Assists Thyroid Conditions
Your thyroid is a small gland located in your throat that has a huge impact on your body. This small gland regulates all the hormones within you and makes sure every hormone is going to the right organ. When this gland doesn’t function properly, you might find yourself experiencing abnormal mood changes, excess weight gain, fatigue, and an increased or decreased appetite. Selenium is able to keep your thyroid working at its best, so you do not go through any of these symptoms.
Health benefits of Selenium: Cures Intracranial Pressure Symptoms
Intracranial pressure symptoms include headache, speech disorder, nausea, vertigo and fatigue. According to research, these symptoms can be treated by increasing intake of selenium.
Health benefits of Selenium: Treats Asthma
It's been found that people who suffer from asthma don't have sufficient amounts of selenium in their bodies. Selenium as well as beta carotene, vitamin C and vitamin E are antioxidants that can prevent and control asthma attacks.
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 they have yet to determine selenium’s full effect on lung function.
Health benefits of Selenium: Can Help Boost Fertility Pregnant Woman
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.
Health benefits of Selenium: Relives Psoriasis and Eczema
Selenium can assist recovery for internal issues like blood pressure and thyroid, and can also relieve external issues like psoriasis and eczema. While this supplement won’t be able to completely clear your skin of these two problems, it can help relieve the symptoms. The constant itchiness and redness caused by eczema can be especially irritating. The many benefits of selenium also include the ability to help any itching and swelling become more manageable.
Health benefits of Selenium: Helps to Eliminate Dandruff
Selenium is beneficial to the hair and scalp. As such, shampoos that contain selenium are effective in treating dandruff problems.
Selenium Side effects and cautions
Taken at normal doses, selenium does not usually have side effects. An overdose of selenium may cause bad breath, fever, nausea, and liver, kidney and heart problems. 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.
Selenium may also interact with other medicines and supplements, such as antacids, chemotherapy drugs, corticosteroids, niacin, cholesterol-lowering statin drugs, and birth control pills. If you take any of these medications, its best to speak with your doctor before supplementing with any vitamins and minerals, including selenium.
Selenium supplements are associated with a risk of skin cancer ( squamous cell carcinoma), so people at high risk of skin cancer should not take these supplements.
Supplements of selenium have been reported as exacerbating low thyroid functioning if such supplements are taken by a person affected by iodine deficiency induced goiter.