Oncology & Cancer

Diet may reduce risk of prostate cancer

A new review published in the Journal of Human Nutrition and Dietetics assessed whether certain modifications in diet have a beneficial effect on the prevention of prostate cancer. Results suggest that a diet low in fat and ...

Health

Why you should stop buying vitamins and get more sleep instead

Almost half of all Canadians regularly take at least one nutritional supplement such as vitamins, minerals, fibre supplements, antacids and fish oils. Many of these individuals are healthy and hoping to improve general well-being ...

Alzheimer's disease & dementia

Vitamin E, selenium supplements did not prevent dementia

Antioxidant supplements vitamin E and selenium - taken alone or in combination - did not prevent dementia in asymptomatic older men, according to a study published online by JAMA Neurology.

Oncology & Cancer

Selenium status influence cancer risk

As a nutritional trace element, selenium forms an essential part of our diet. In collaboration with the International Agency for Research on Cancer, researchers from Charité - Universitätsmedizin Berlin have been able to ...

Cardiology

Selenide protects heart muscle in the wake of cardiac arrest

Damage to heart muscle from insufficient blood supply during cardiac arrest and reperfusion injury after blood flow is restored can be reduced by nearly 90 percent if selenide, a form of the essential nutrient selenium, is ...

Ophthalmology

Cataract risk not down with long-tem selenium, vitamin E

(HealthDay)—Long-term supplementation with selenium or vitamin E is not associated with a reduction in the risk of age-related cataract among men, according to a study published in the January issue of JAMA Ophthalmology.

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Selenium

Selenium (pronounced /səˈliːniəm/) is a chemical element with the atomic number 34, represented by the chemical symbol Se, an atomic mass of 78.96. It is a nonmetal, chemically related to sulfur and tellurium, and rarely occurs in its elemental state in nature.

Isolated selenium occurs in several different forms, the most stable of which is a dense purplish-gray semi-metal (semiconductor) form that is structurally a trigonal polymer chain. It conducts electricity better in the light than in the dark, and is used in photocells (see allotropes section below). Selenium also exists in many non-conductive forms: a black glass-like allotrope, as well as several red crystalline forms built of eight-membered ring molecules, like its lighter chemical cousin sulfur.

Selenium is found in economic quantities in sulfide ores such as pyrite, partially replacing the sulfur in the ore matrix. Minerals that are selenide or selenate compounds are also known, but all are rare. The chief commercial present uses for selenium are in glassmaking and in chemicals and pigments. Electronic uses for selenium, once important, have been supplanted by silicon semiconductor devices.

Selenium salts are toxic in large amounts, but trace amounts of the element are necessary for cellular function in most, if not all, animals, forming the active center of the enzymes glutathione peroxidase and thioredoxin reductase (which indirectly reduce certain oxidized molecules in animals and some plants) and three known deiodinase enzymes (which convert one thyroid hormone to another). Selenium requirements in plants differ by species, with some plants apparently requiring none.

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