Selenium is an essential mineral found in minute amounts in the body. It is one of the essential body substances that can be used in a preventive manner for many diseases, including cancer, arteriosclerosis, stroke, cirrhosis, arthritis and emphysema. Selenium works closely with vitamin E in some of its metabolic actions and in the promotion of normal body growth and fertility. Selenium is a natural antioxidant that protects against free radicals and appears to preserve elasticity of tissue that becomes less elastic with aging.
Selenium improves certain energy producing cells, including those of the heart, by ensuring adequate oxygen supply.
The selenium content of food is dependent upon the extent of its presence in the soil, whether directly, as in plant foods, or indirectly, as in animal products whose selenium levels are derived from feed. Even if selenium levels are adequate in the soil, the sulfur contained in widely used fertilizers and sulfuric compounds found in acid rain inhibit plant absorption of the mineral.
Selenium compounds in foods are easily reduced by heat, processing, and cooking. Refining of grains reduces selenium content, by 50 to 75 percent, boiling by 45 percent.
Good food sources of selenium are brewer’s yeast, organ and muscle meats, fish and shellfish, grains, cereals, and dairy products.
Absorption and Storage
The liver and kidneys contain four to five times as much selenium as do the muscles and other tissues. Selenium is normally excreted in the urine; its presence in the feces is an indication of improper absorption. Because it binds with toxic metals, the ingested selenium may be assimilated.
Dosage and Toxicity
The National Research Council recommends 50 to 200 micrograms. The average “good” diet may contain only 35 to 60 micrograms per day.
Doses should not exceed 700 to 1110 micrograms daily for long periods of time unless under the supervision of a physician.
Male sperm cells contain high amount of selenium. Substantial amounts are lost during sexual intercourse. For this reason, selenium requirements may be higher for men than for women. Male sperm cells contain high amount of selenium. Substantial amounts are lost during sexual intercourse. For this reason, selenium requirements may be higher for men than for women.
High levels of selenium in soil have caused toxicity and some deaths in animals who grazed on the grains. Selenium also contaminates water supplies located near irrigated land. Selenium intoxication has been reported as a result of industrial inhalation.
Toxic symptoms are loss of hair, teeth, and nails; dermatitis; lethargy; and paralysis. Severe overdose produces fever, an increased respiratory and capillary rate, gastrointestinal distress, myelitis, and sometimes death.
Selenium overdoses can interfere with fluorides assimilation, which helps to prevent tooth decay.
Deficiency Effects and Symptoms
A deficiency of selenium may lead to premature aging. This is because selenium preserves tissue elasticity.
A defective selenium absorption mechanism can result in neuronal ceroid lipfuscinosis, a disease that accumulates pigment in nerve cells and is characterized by mental retardation, diminished vision, nerve disorders,, and eventually death.
Selenium is essential for reproduction. Animal tests reveal that selenium deficient rats produced immobile sperm and most of the sperm were broken near the tail. Other studies show that selenium deficiency results in infertility.
Studies in Australia show that a selenium deficiency may relate to crib death.
Beneficial Effect on Ailments
Selenium when combined with protein is beneficial in treating kwashiorkor, a protein deficiency disease.
Dr. Julian E. Spallholz of the Veterans Administration Hospital in Long Beach, California, has demonstrated through experiments with mice that selenium may increase resistance to disease by increasing the number of antibodies that neutralize toxins. Selenium supplements enabled mice to produce significantly more antibodies than those not given the trace element.
Archives of Environmental Health, September/October 1976, reports that in a study of the relationship between cancer incidence and soil distribution of selenium levels showed significantly lower overall male cancer death rates. Also in these areas, in those organ systems involved with the assimilating, metabolism, and excretion of selenium.
Selenium may improve energy levels, prevent and relieve arthritis, slow down the aging process by attacking free radicals, and prevent cataracts.
It is an important element that protects against high blood pressure, stroke, heart attack, and hypertensive kidney damage. Selenium with Vitamin E has been used successfully in reducing or eliminating recurrent angina attacks and increasing strength and vigor and improving electrocardiograms in heart patients.
It has been used successfully in improving the condition of persons with cystic fibrosis. Muscular dystrophy patients respond positively to selenium and vitamin E. Research I the early 1970’s has proved that selenium protects against radiation. It also binds to metals such as mercury, cadmium, silver, and thallium, preventing their absorption in the body and aiding their excretion.