An essential nutrient is a nutrient, e.g. trace mineral, required for normal body functioning but cannot be synthesized by the body, and therefore must be supplied through diet. The need for selenium as an essential element (mineral) in nutrition for the prevention of disease was established by Schwarz and Foltz in 1957.
Epidemiological investigations in Finland, a low-selenium area, indicated an association of low nutritional selenium status and increased cardiovascular disease. It also has been postulated that an unusually high mortality rate from cardiovascular disease in southwestern Georgia (U.S.) might be due to selenium deﬁciency.
Examples of Selenium Deficiency Conditions in Animals
Selenium deﬁciency has been linked with a number of symptoms in animals. Human selenium deﬁciency has been well documented in the pathogenesis and pathology of Keshan disease – a multifactorial myocarditis occurring in the Chinese province of Keshan, where the soil, from which the food that feeds the population grows, is severely lacking in selenium. Besides cardiomyopathy, the following clinical and/or laboratory manifestation of selenium deﬁciency in humans have been described: goiter (enlargement of thyroid due to iodine deﬁciency aggravated by selenium deﬁciency), myositis (inﬂammation of muscles), whitening of the ﬁngernail beds, pseudoalbinism (skin changes), elevated creatinine kinase derived from muscles (enzyme indicative of muscle damage), macrocytosis, osteoarthropathy (known as Kashin-Beck disease, a degenerative bone condition occurring in regions of Tibet where the soil lacks selenium) and male infertility.
Epidemiological investigations in Finland, a low selenium area, indicated an association of low nutritional selenium status and increased cardiovascular disease. It also has been postulated that an unusually high mortality rate from cardiovascular disease in southwestern Georgia (U.S.) might be due to selenium deﬁciency. The inverse association between selenium levels and the carcinogenesis in various sites of the body including cancer of the liver, mammary gland, esophagus, stomach, colon, rectum, lung, urinary tract, prostate, female reproductive organs, thyroid, hematologic system, oral cavity, pharynx, and skin has been noted.