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Deficiency Diseases and Good Nutrition
Selenium
Se
Selenium was named after the mysterious God of the moon, Selene. This mineral is poisonous as it exists in the soil, but plants change it to a form we can use. Selenium is most abundant in soil containing volcanic ash. The soil in northeastern, Pacific, southwestern, and extreme southeastern regions of the U.S. are deficient in selenium. In Canada, the north central and eastern regions are deficient. Food grown in these areas will also be deficient in the mineral. Energy is captured from the food you eat through a process of reactions that go on in every cell. In these reactions, electrons are moved through a process that produces energy. This series of chemical reactions could not take place without enzymes containing or needing selenium. Coenzyme Q requires the presence of selenium to work correctly. Without it, the process would be interrupted and cells would not have energy. Glutathione peroxidase contains four atoms of selenium, and works as an antioxidant. Sometimes in the energy producing process, molecules can "break", creating dangerous oxidants that ruin your cell membranes. Glutathione peroxidase stops these oxidants before they can do any damage. Without selenium, glutathione peroxidase cannot be produced and your cell membranes could be destroyed.

Selenium also helps to recycle iron from red blood cells. When a red blood cell dies, the iron from that cell bonds to a protein, and forms ferritin. By itself, iron can be filtered out by the kidney, but ferritin is too large to be filtered, thus the iron in it is saved. Transferrin is needed to bind the iron and protein, and selenium helps it to perform this function.

Selenium is a great help to the immune system. It aids in the protection of macrophages, which are large white blood cells who eat viruses, bacteria, and other foreign elements. Selenium helps in the manufacture of interferon, which stops viruses from reproducing. Vitamin A plays a big role in the immune system, and selenium keeps it from being oxidized.

Joints benefit from an adequate intake of selenium. Mucopolysaccharides need selenium to be produced. These molecules lubricate joints and keep them working longer. Without lubrication, the bones in your joints would grind on each other and possibly cause rheumatoid arthritis.

Selenium has the ability to bond with heavy metals in your body. These metals can get inside you from pollution in the air, cigarette smoke, or from the food you eat. When selenium bonds to hazardous metals they can be safely excreted from your body. If they are not excreted, they may damage your organs and even cause cancer.

This may be one reason why scientists believe adequate selenium intake can prevent some cancers. In areas where the soil is deficient in selenium, there is a higher incidence of cancer. Some cancers are caused by free radical oxidation, which selenium prevents. Selenium also encourages the production of macrophages who "eat" foreign material that may cause cancer. It is important to eat foods containing selenium. When foods are processed, all the selenium is destroyed. Once again, if you eat whole natural foods, you will get enough selenium to prevent cancer and rheumatism, and keep your cell membranes healthy.



Foods High in Selenium

Brazil nuts, 1/4 cup          380 mcg
Snapper, baked, 3 oz.         148 mcg
Halibut, baked, 3 oz.         113 mcg
Salmon, baked, 3 oz.           70 mcg
Scallops, steamed, 3 oz.       70 mcg
Clams, steamed, 20             52 mcg
Oysters, raw, 1/4 cup          35 mcg
Lasagna, with meat, 1 piece    34 mcg
Wheat germ, toasted, 1/4 cup   28 mcg
Molasses, blackstrap, 2 Tbls.  25 mcg
Sunflower seeds, 1/4 cup       25 mcg
Granola, 1 cup                 23 mcg
Ground beef, 3 oz.             22 mcg
Chicken, breast, baked, 3 oz.  17 mcg
Bread, whole wheat, 1 slice    16 mcg
Egg, 1                         12 mcg
Milk, 2%, 1 cup                 6 mcg
Cheese, cheddar, 1 oz.          4 mcg

Men need more selenium that women, because there is a high concentration of selenium in seminal fluid. Adequate selenium may lower the risk of impotence and sterility.



RDA for Selenium

  Age        RDA
0.0-0.5     10 mcg
0.5-1.0     15 mcg
1-6         20 mcg
7-10        30 mcg
11-14 (men) 40 mcg
  (women)   45 mcg
15-18       50 mcg
19+ (men)   70 mcg
  (women)   55 mcg
Pregnant    65 mcg
Lactating   75 mcg

Selenium deficiency is very rare in humans. When the soil has a low selenium content, two diseases occur. Keshan disease affects the health of your heart, and can be prevented by selenium intake. Once you have the disease, selenium supplementation will not help you, as the effects of the disease are permanent. The other disease is Kashin-Beck disease. Characteristics of the disease are swelling and stiffness of the joints in your fingers and arthritis in your elbows, knees, and ankles. This is probably due to the absence of mucopolysaccharides.

There is no known toxicity of the element.

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Revised: 14 Sep 99