The following is a listing of vitamins and minerals complete with a brief discussion of their function in your body, what foods supply the particular micronutrient, and the Recommended Dietary Allowance (RDA) - which is a reference number developed by the United States Food and Drug Administration to help consumers determine how much of a specific micronutrient a food contains. Summaries of the RDAs for vitamins and minerals are presented in Table 5.3 (below). The equivalent table for minerals is not shown in this excerpt.) Notice that RDAs are frequently gender and age dependent, and pregnant and nursing women most often have special micronutrient needs.
Because of the rapid expansion of scientific knowledge regarding the role of micronutrients in human health, the U.S. Food and Drug Administration, in partnership with Health Canada, periodically assesses and updates the recommended Daily Values. The following contains the recommended RDAs as of April 2006 for the vitamins and minerals discussed.
Vitamin A is a collection of fat-soluble compounds that play an important role in vision, bone growth, reproduction, cell division, and help prevent or fight off infections. Vitamin A also promotes healthy surface linings of the eyes, respiratory, urinary, and intestinal tracts, and also helps maintain the integrity of skin and mucous membranes. Using the long-established International Unit (IU) measure for the recommended dietary allowance (RDA), adult men and women need 3,000 and 2,330 IU (as retinol) per day respectively. However, the new RDA measure for vitamin A is the microgram (mcg), which translates for men and women as 900 and 700 mcg per day. Foods rich in vitamin A are orange-colored vegetables such as carrots, sweet potatoes and pumpkin; dark-green-leafy vegetables like spinach, collards and romaine lettuce; and orange-colored fruits such as mango, cantaloupe and apricots; and red peppers and tomatoes. One medium-size carrot supplies approximately 270 percent of your RDA.
Vitamin D is a fat-soluble vitamin. Briefly, vitamin D is important in assisting the absorption of calcium, in forming strong bones and teeth and preventing deficiency diseases such as rickets and osteomalacia. For most adults, an adequate intake of vitamin D is 200 to 600 IU (which is equivalent to 5 to 15 mcg per day). In addition, your body can make vitamin D after exposure to sunshine. Good food sources include salt-water fish such as herring, salmon, sardines and fish-liver oils, as well as fortified milk and cereals. Small quantities are also found in egg yokes, veal and beef. 250 mL of fortified milk supplies about 25 percent of your daily needs.
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