Category: Natural chemicals
Introduction and description
Selenium is a chemical element with symbol Se. It is a nonmetal. Although it is toxic in large doses, selenium is an essential micronutrient for animals.
In plants, it occurs as a 'bystander mineral', sometimes in toxic proportions in forage. Some plants may accumulate selenium as a defense against being eaten by animals, but certain species of plants are considered indicators of high selenium content of the soil, since they require high levels of selenium to thrive. The main selenium indicator plants are Astragalus species (including some locoweeds), prince's plume (Stanleya sp.), woody asters (Xylorhiza sp.), and false goldenweed (Oonopsis sp.).
The human body's content of selenium is believed to be in the 13–20 milligram range. The biological function of Selenium in the human body are as follows:
- Antioxidant - In humans, selenium is a trace element nutrient that functions as cofactor for reduction of antioxidant enzymes. One family of selenium-containing molecules (the glutathione peroxidases) destroy peroxide and repair damaged peroxidized cell membranes, using glutathione.
Peroxides are chemicals that have a bleaching effect on organic substances and therefore are added to some detergents and hair colorants. Other large-scale applications include medicine and chemical industry, where peroxides are used in various synthesis reactions or occur as intermediate products. Thus selenium has a role in repairing damage if you are exposed to this toxin.
- Thyroid regulation - Selenium also plays a role in the functioning of the thyroid gland and in every cell that uses thyroid hormone, by participating as a cofactor for the three of the four known types of thyroid hormone deiodinases, which activate and then deactivate various thyroid hormones and their metabolites.
Selenium may inhibit Hashimoto's disease, in which the body's own thyroid cells are attacked as alien. A reduction of 21% on TPO antibodies was reported with the dietary intake of 0.2 mg of selenium.
- Reproduction system and fertility - there appears to be some connection between selenium and fertility - or at least the viability of sperm, for example
Low sperm production and poor sperm quality are consistent features of Se-deficient animals. The pivotal link between Se, sperm quality and male fertility is GPX4 since the enzyme is essential to allow the production of the correct architecture of the midpiece of spermatozoa. Se also has insulin-mimetic properties, an effect that is probably brought about by stimulating the tyrosine kinases involved in the insulin signalling cascade. Furthermore, in the diabetic rat, Se not only restores glycaemic control but it also prevents or alleviates the adverse effects that diabetes has on cardiac, renal and platelet function. PMID: 15749805
The additional paragraph at the end indicates a possible role in other hormone and endocrine systems as well
- Chelation - Increased dietary selenium intakes reduce the effects of mercury toxicity and it is now recognized that the molecular mechanism of mercury toxicity involves irreversible inhibition of selenoenzymes that are required to prevent and reverse oxidative damage in brain and endocrine tissues
- Anti-fungal agent - The substance loosely called selenium sulfide (approximate formula SeS2) is the active ingredient in some anti-dandruff shampoos. The selenium compound kills the scalp fungus Malassezia, which causes shedding of dry skin fragments. The ingredient is also used in body lotions to treat Tinea versicolor due to infection by a different species of Malassezia fungus.
Illnesses and diseases of Selenium imbalance
It is possible to be both deficient in Selenium and also to overdose. Overdosing causes Selenosis. See Selenium imbalance.
Dietary selenium comes from:
Fish and shellfish – particularly tuna, crab and lobster, as well as mackerel, smoked salmon, pickled herring, canned sardines, blue mussels, swordfish. Marine fishes and vertebrate thyroid glands have the highest concentration of selenium and iodine.
Nuts – brazil nuts are the richest dietary source, but other nuts also contain selenium
Eggs – the white contains more thna the yolk
Cereals – principally wheat, but also barley malt
Offal – particularly kidney and also liver
Seeds – particularly sunflower seeds, but also sesame seeds
- Arsenic, selenium and Vitamin E 013089
- Biomonitoring Equivalents for selenium 013095
- Cadmium poisoning and selenium 013088
- Citrus fruits, kaffir lime leaves, selenium and its anti-depressant effect 013090
- Cod liver oil and respiratory tract infections in children 012185
- Curing AIDS and HIV in Botswana 013082
- Dairy products vitamins and mineral 005906
- Dietary Strategies for the Treatment of Cadmium and Lead Toxicity - 02 Essential metals 016836
- Dr Duke's list of chemicals and activity for the Shallot 017969
- Dr Duke's list of chemicals which are an Antidote to Mercury [causing Meniere's disease] 021286
- Dr Duke's list of chemicals with AntiHIV activity 017977
- Dr Duke's list of Plants containing SELENIUM 020550
- Dr Duke’s list of Chemicals and their Biological Activities in: Cucurbita pepo L. (Cucurbitaceae) -- Zucchini 027494
- Evaluation of the halophyte Salsola soda as an alternative crop for saline soils high in selenium and boron 021289
- Fish, heart and blood circulatory problems and mercury 012482
- Heavy metal poisoning and learning difficulties in children from Brazil 013085
- How to Rid Your Body of Mercury and Other Heavy Metals: A 3-Step Plan to Recover Your Health 026662
- Meat, offal, heavy metals and minerals 005485
- Mercury in foods and fish and selenium as a chelation agent 013083
- Nutrition and the psychoneuroimmunology of postpartum depression 027723
- Psoriasis and nutrition 012060
- Selenium and its effect on toxin induced IBS 013091
- Selenium and mercury in the brains of Beluga whales 013092
- Selenium and mercury poisoning 006296
- Selenium and toxin [acrylamide] induced eye damage 013094
- Selenium as an alternative to chemotherapy 013093
- Selenium in edible mushrooms 018156
- Selenium in reproductive health 016787
- Selenium to heal psychosis 013080
- Selenium, aflatoxins and liver disease and damage 013087
- Selenium, chemotherapy and heart disease 013084
- The effect of selenium on carbendazim induced oral sub chronic toxicity 013086
- The role of selenium in human conception and pregnancy 016786
- The role of thiols, dithiols, nutritional factors and interacting ligands in the toxicology of mercury 017752
- USDA Nutrients - Fish, Herring 012459
- USDA Nutrients - Fish, Mackerel 012472
- USDA Nutrients - Fish, Oysters 012458
- USDA Nutrients - Fish, Salmon 012487