Selenium nutritional excess

Selenium, an essential dietary nutrient, when fed to animals in amounts seemingly in nutritional excess or when administered by injection acts as an Immunoadjuvant. When fed or administered at toxic levels Se becomes more immunosuppressive. 

Selenium is found in meat and other foods due to water pollution. Although it is believed to be essential in the diet, there are indications that excessive amounts of selenium may be toxic. Studies are under way to determine the amount required for good nutrition and the amount that may be harmful. The standard for selenium is 0.01 mg/L of water. If selenium came only from drinking water, it would take an amount many times greater than the standard to produce any ill effects. 

The development, maintenance, and optimal functioning of the immune system are dependent on balanced and adequate nutrition. However, either a deficiency or an excess of a number of nutrients can have adverse effects. The nutrients with the most pronounced effects in humans include amount and type of dietary fatty acids (FAs), protein energy malnutrition, vitamins A, B6, B12, C, and E, and minerals including zinc, copper, selenium, and iron. Multiple rather than single nutrient deficiencies... 

Selenium is known to be an essential micronutrient for humans and other animals both inadequate and excessive selenium intake can cause adverse health effects. However, most people in the United States are unlikely to suffer from selenium deficiency. The current recommended dietary allowance (RDA) for selenium established by the Food and Nutrition Board of the National Research Council is 55 pg/day for adults. Adverse health effects due to selenium are generally observed at doses at least 5 times greater than the RDA. 

SPECIALTY FOODS AND HIGHLY POTENT NUTRITIONAL SUPPLEMENTS. It is fortunate that most consumers are not able to purchase pure mineral salts and to mix them into their foods, because without special measuring equipment and experience in preparing such mixtures, it is very easy to add toxic excesses of trace elements like iodine and selenium to foods. However, even some of the products that are sold by health food stores may have undesirable, or even toxic effects, because they are very rich in certain minerals. The potentially hazardous products may be considered as highly potent nutritionai suppiements, in order to distinguish them from the less potent specialty foods, which are usually safe in the amounts consumed. Table M-27 shows the approximate amounts of these minerals that are provided by various specialty foods and nutritional supplements. 

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