SELENIUM (Se)

General - trace mineral; anti-oxidant mineral; “youth” element;

• Selenium is an anti-oxidant nutrient, like vitamins C and E;
• Adult body contains less than 15 mg of selenium;
• Belongs to sulfur family of elements; complexes with sulfur amino acids methionine & cysteine;
• Considered poisonous for years, it is now known that selenium prevents liver tissue degeneration;
• History: selenium deficiencies reported by Marco Polo in 1295; shown to cause alkali disease in livestock in 1930’s; essentiality for animals established in 1957; first description of selenium deficiency in animals in 1969; first reports of possible significance to human health in 1979;

Nutrition

• Sources: best: organ meats, sea foods, foods grown on selenium-rich soils, garlic, onions, yeast; fair: meats, whole grains; poor: plant foods, foods grown on selenium-poor soils;
• Supplements: selenium salts, amino acid chelates, multi-mineral, multi-mineral-vitamin, garlic, yeast;
• Absorption from small intestine; efficiently (80%) absorbed;
• Antagonized by: sulfur & sulphates inhibit plants’ absorption of selenium; refining loses 50 -75% of selenium; boiling loses 45%;
• Storage: distributed in all cells; elevated quantities found in liver, kidneys & pancreas; cardiac muscle higher in selenium than skeletal muscle; low in lung & brain;
• Excretion: mainly through urine; traces lost in feces and breath;
• Metabolism: virtually impossible to obtain enough selenium from dietary sources; supplementation of organic (yeast-bound) selenium or amino acid chelated recommended; synergistic with vitamin E;
• Interactions: selenium requirement is inversely proportional to level of vitamin E; toxic selenium level interferes with fluorine metabolism & may increase tooth decay; vitamin C taken at same time as inorganic selenium salt (sodium selenite) may render this selenium non-absorbable; organic forms of selenium remain active in the presence of vitamin C;

Functions of selenium

• Important in anti-oxidant function — present in glutathione peroxidase, a 3-amino acid peptide that prevents damage to cells by neutralizing hydrogen peroxide (H2O2) & hydroperoxides of fatty acids in membranes;
• Selenium is a free radical scavenger; works in association with vitamin E; helps maintain cell membrane integrity by protecting membrane lipids from oxidative destruction;
• Selenium needed for function of liver’s detoxification (cytochrome P-450) system; protects liver from toxin & free radical damage & maintains normal liver function;
• Selenium plays its protective function in nucleic acid metabolism; protects against cancer;
• Protects heart and liver from free radical damage; helps control lipid peroxidation;
• Protects against lack of oxygen, improving function of mitochondria by preventing free radical damage;
• Helps make prostaglandins that lower blood pressure, make platelets less sticky & help remove water & sodium from body through kidneys; prevents congestive heart failure due to selenium deficiency (Keshan disease); higher tissue selenium correlates with lower incidence of all cardiovascular disease conditions;
• Involved in the production of anti-inflammatory prostaglandins; helpful in arthritis & inflammation of tissues;
• Protects against heavy metal toxicity & harmful effects of lead, mercury, cadmium, silver & arsenic;
• Selenium plus vitamin E can improve immune system protection by 20 to 30 times; together, selenium + vitamin E work better than either one alone (synergistic); selenium may inhibit production of immune-suppressive prostaglandins; selenium may protect immune cells (macrophages) against the free radicals they generate to kill bacteria;
• Active in maintenance of skin elasticity and hair (keratin protein); reduces chances of skin cancer;
• Required in metabolism of pancreas, liver & immune system;
• Important in reproductive processes; sperm is high in selenium; males may require more selenium than females;
• Selenium inhibits all of the major mechanisms that underlie aging;
• Extends life span in animals;

Quantities

• Measurement: micrograms;
• Optimum: (SONA) average ranges have not yet been determined; 400 to 1000 μg/day confer optimum protection;
• Individual optimum needs to be determined for each individual case;
• Minimum: (DRI) 55 μg/day for men & women;
• Less than RDA: no official figures, but estimates go up to 60% of population;
• Deficiency from soil deficiency that is wide-spread in North America, especially in areas of heavy glaciation during last Ice Age; food deficiency follows soil deficiency;
• Symptoms include: signs of premature aging; cataract formation; anaemia; infertility; nutritional muscular dystrophy; strong correlation of low selenium with cancer & cardiovascular incidence; Keshan disease — heart muscle wasting; Kashin-Beck disease affects cartilage in joints; muscular discomfort; lipid accumulation in nerve cells, mental retardation, nerve disorders, diminished vision, premature death;
• (Animals) hair loss, growth retardation, reproductive failure; pancreatic atrophy, myopathy, nephrosis, liver degeneration;
• Toxicity: deterioration & loss of fingernails at 1000 μg/day inorganic & 2000 to 3000 μg/day organic selenium; maximum recommended dose has been set at 500 μg/day;

Therapy with selenium

• Reverses selenium deficiency, that is especially common in vegetarians, those eating foods grown on selenium-deficient soils; those eating highly refined & processed diets (teenagers, the elderly, the poor & poorly educated); pregnant & nursing mothers; smokers; those exposed to heavy metals and toxins that create free radicals;
• At 200 - 300 μg/day, helps to reduce cancer risk, according to research by Schrauzer (U. of California) & Tolonen (Finland); appears to protect against breast, colon, ovary, pancreas, prostate, lung & bladder cancers;
• Protects against the development of high blood pressure, stroke, heart attack & hypertensive kidney damage;
• At 100 - 200 mcg/day, selenium has helpful anti-inflammatory effects on rheumatoid arthritis;
• Used to increase resistance to disease by increasing production of detoxifying antibodies;
• Used to improve cystic fibrosis &, with vitamin E, muscular dystrophy;
• Used to protect against damage due to radiation;
• Prevents chromosome breakage in tissue culture;
• Used with protein to treat protein deficiency disease (kwashiorkor);
• Synergists: containing-containing proteins; vitamins A, C & E; balanced diet & supplements;