Selenium
SELENIUM is a non-metallic element named from the Greek word selen meaning "moon." Its toxic effects were known long before the cause. In 1295, Marco Polo became the first to observe that certain forage plants, which grew in the mountains of western China, caused the hooves of grazing animals to drop off. Records from 1856 indicate that cavalry horses in Nebraska lost their hooves, along with some of their hair, while feeding on native forage plants. Similar observations were reported in 1893 in Wyoming. Today, we know these conditions were the result of selenium poisoning. Such historical observations are scarce, since there are only a few places in the world where toxic levels of selenium are found in plants or the soil. These animal disorders were traced to plants called "locoweeds" and "poison vetches" (generally, species astragalus and oxytropis). But it was not until the 1930's that agricultural researchers linked the two by showing that some plants contained abnormally high levels of selenium and that animals feeding on these plants developed the disorders.
Selenium was discovered in 1817 by a Swedish scientist while he was working with flue dust left after the burning of sulfuric acid. It was quickly noted that he had a "garlic" smell to his breath. Soon, he had isolated the offending substance as selenium. Because selenium and sulfur have similar chemical properties, selenium often occurs as a trace contaminant of substances containing sulfur. In addition, selenium is often obtained as a byproduct of copper refining. Red in color, it is used for paints tints, inks, car tail-lights and in the making of photoelectric cells that sense light or turn it into electricity.
Early in the last century, the FDA warned that insecticides containing selenium might be hazardous to humans, but it was not until 1943 that scientists produced nonmalignant liver tumors in rats from such materials. Because of these early findings, the FDA has been cautious about approving selenium for nutritional supplements. In the 1950's, its nutritional benefits began to emerge, after it was discovered in American-type brewer's yeast as part of an unidentified 'factor 3' which apparently acts with Vitamin E and sulfur-containing amino acids in protecting the liver. Consequently, selenium was granted an "essential to life" status.
Since then, discoveries have shown that selenium prevents certain disorders resulting from Vitamin E deficiency including a type of muscular dystrophy suffered in animals. The anitoxidant properties that selenium has works synergistically with Vitamin E, which means that the two together are stronger than each on its own. When a selenium deficiency exists, this severity can be aggravated by too little Vitamin E and a deficiency of either one of these nutrients can be corrected by supplementation of the other. In 1973, it was discovered that selenium, with Vitamin E, acted as a cofactor for the enzyme glutathione peroxidase. This enzyme is known to break down toxic peroxides formed from the oxidation of polyunsaturated fats.
For many years, it was ignored as being an essential element because it was known to be highly toxic. However, in 1990, the National Research Council decided that the RDA for selenium should be 200 mcg. per day, along with the advisory not to exceed this amount as it can be toxic in its pure form. Just one organically grown raw Brazil nut will supply enough selenium needed for the whole day.
Selenium has already proven to contribute to sperm production and motility. Boys who reach puberty require more than girls because half of a male's body concentrations of selenium is found in the testicles and seminal ducts and lost during semen emissions.
Recent findings are showing that selenium does help in protecting against cancer in that it seems to neutralize certain carcinogens eaten in foods and that it can prevent the spread of some existing tumors. Its function also tends to improve oxygen utilization, thereby helping the heart and lungs. Other findings include its ability to improve elasticity in tissues and muscles, maintain healthy red blood cells and keratins, contribute to the tough proteins of hair and nails, and help in the treatment and prevention of dandruff. Selenium is proving invaluable in detoxifying such heavy metals as mercury, cadmium, and silver, as well as that of various drugs, cigarette smoke, and some types of carcinogenic fats. It is thought that the element combines with toxins, yielding inert compounds.
Selenium also acts as an anti-inflammatory agent in the treatments of arthritis and other autoimmune diseases, thereby being of some benefit to the immune system. It is being used to treat a condition called Kashin-Beck disease, which affects the joints. If caught soon enough, selenium can be effective against growth retardation, joint enlargment, and defects in the spinal column as well as muscular atrophy. It also functions in the thyroid hormone metabolism and in the pancreas. Not until 1979 did Chinese scientists associate selenium deficiency with Kershan disease, a fatal cardiomyopathy disease that occurs most frequently in children and women of child-bearing age. Some scientists feel that selenium deficient people are more prone to a virus which may cause the disease, rather than solely from a deficiency of selenium.
Selenium is easily destroyed by food processing. To make matters worse, its content in foods is directly related to the soil content where foods are grown. Even though it is one of the ten most common minerals, its distribution is uneven. Some areas are rich in selenium while neighboring lands are depleted. Deficiencies occur in areas devoid of selenium in the soil in parts of China, New Zealand, and Finland.
Summary:
Names include: Se, Se-2. Se--, and element 34.
Deficiency symptoms include: dandruff, decreased tissue elasticity, deterioration and calcification of muscle tissue, sterility in males, fetal death, decreased ozone resistance, low blood selenium levels, abnormal nailbed growth, retarded growth, muscle cramps, heart enlargement, and varying degrees of heart insufficiency. Deficiencies occurring in warm blooded animals have produced cataracts, muscular dystrophy, liver disease, infertility, heart problems, cancer, arteriosclerosis, arthritis, cirrhosis of the liver, and emphasema.
Toxicity symptoms include: garlicky skin smell, bad breath, deterioration of hair/nails/teeth, skin inflammations, fatigue, irritability, and progressive paralysis. Early signs of selenium toxicity are lethargy, irritability, dry hair, and fingernail changes.
Inhibitors include: food processing, which removes the mineral.
Helpers include: Vitamin E and chromium.
