A vitamin that consists of eight components: four tocopherols (of which alpha tocopherol is the most common constituent) and four tocotrienols. Vitamin E is an antioxidant found in many common foods. Deficiencies of the vitamin in the general population are rare.
1. Doses of vitamin E in excess of 100 mg/kg/day in low birth weight neonates have been implicated in the development of necrotizing enterocolitis and sepsis. 2. Vitamin E supplementation in adults that exceeds 400 International Units/day increases mortality.
An antihemorrhagic factor whose activity is associated with compounds derived from naphthoquinone. Vitamin K is fat soluble, and is found in broccoli, collards, beet greens (most green vegetables); vitamin K2, is found in fishmeal. Vitamin K3 is synthesized as menadione sodium bisulfite. Vitamin K is necessary for synthesis of clotting factors VII, IX, X, and prothrombin by the liver. Its deficiency prolongs blood-clotting time and causes bleeding. Its roles in bone metabolism include the conversion of osteocalcin to its active form and matrix Gla-protein (MGP) function in bones, teeth, and cartilage. Within the kidney, vitamin K inhibits the formation of calcium oxalate stones. It appears to have a role in normal retinal signaling. In the newborn, the colon is sterile until food is ingested and bacteria colonize the site. Because this bacterial source of vitamin K is not immediately available, an intramuscular injection of 1 mg of water-soluble vitamin K1 (phytonadione) is recommended for all newborns.
Large doses may cause hemolysis in those with glucose-6-phosphate dehydrogenase deficiency and in some healthy people. Large doses in the newborn may lead to anemia and kernicterus. The recommended adult daily allowance is 65 µg for women and 80 µg for men.
ACTION/USES: Vitamin K helps to eliminate prolonged bleeding in operations and in the biliary tract of jaundiced patients. Bile salts are necessary for its absorption.
A vitamin tablet or capsule containing one or more vitamins. Some supplements may contain more than a dozen vitamins and an even greater number of minerals. In general, healthy adult men and healthy nonpregnant, nonlactating women consuming a normal, varied diet do not need vitamin supplements.
The difficulties of people who take vitamin supplements are: 1. People who take the supplements are usually already consuming an adequate diet. 2. The vitamins chosen are often not the ones inadequate in their diet. 3. The dose may be many times greater than the daily needs. SEE: Food Guide Pyramid; vitamin C.
(vī-tĕl′ĭn) A protein that can be extracted from egg yolk and contains lecithin. SEE: nucleoprotein; ovovitellin.