Vitamins are so widely distributed in food that a properly prepared normal diet usually provides an adequate amount. Vitamins can be destroyed during the preparation or preservation of certain foods; however, manufacturers frequently add vitamins to their products to replace those destroyed or removed in processing. Since fat-soluble vitamins can be stored in the body, it is possible to develop hypervitaminosis by consuming excessive amounts of these nutrients, and death may result in extreme cases. Fat-soluble vitamins include A, D, E, and K.

Vitamin A is involved in the formation and maintenance of healthy skin, hair, and mucous membranes. Vitamin A helps us to see in dim light and is necessary for proper bone growth, tooth development, and reproduction. Good sources of vitamin Ainclude yellow, orange, and dark green vegetables; fruits; and liver, eggs, cheese, butter, and milk.

Vitamin D promotes calcium and phosphorus absorption and is required for the formation of healthy bones and teeth. Good sources include fortified milk, egg yolk, liver, tuna, and cod liver oil. Vitamin D is produced in the body on exposure to sunlight.

Vitamin E protects vitamin Aand essential fatty acids from oxidation in the body cells and prevents breakdown of body tissues. Good sources include vegetable oils, fortified cereals, whole-grain cereals and bread, nuts, wheat style="mso-spacerun: yes"> germ, and green leafy vegetables.

Vitamin K includes a group of vitamins that promote normal clotting of the blood and helps maintain normal liver functions. Good sources are green leafy vegetables, liver, soybean, and other vegetable products.

Water-soluble vitamins, such as vitamin C and the B-complex vitamins, are not stored in the body to any great extent. Rather, they are used as necessary by the body, and any amounts that remain are excreted in the urine. As a result, these vitamins must be replenished daily to ensure optimum health.

Vitamin C (ascorbic acid) is necessary for normal growth and cell activity and is important for maintaining blood vessel strength. It helps the body resist upper respiratory infections and is necessary for the proper development of teeth and gums. Wounds and burns require vitamin C for healing. Adeficiency of ascorbic acid causes an individual to bruise easily. A severe deficiency leads to a condition known as scurvy. Good sources include citrus fruits, raw leafy vegetables, and tomatoes.

Vitamin B (Complex) includes more than 12 separate B vitamins. Some of the more common B vitamins are

Table 9-1.-Mineral Elements in Nutrition

-Thiamin (B1) is necessary for normal growth, normal carbohydrate metabolism and normal functioning of the heart, nerves, and muscles. Thiamin deficiency results in retarded growth and nerve disorders, and a condition known as beriberi. Good sources include pork, fish, eggs, and whole-grain cereals.

-Riboflavin (B2) is required for normal growth, vigor, healthy skin and mucosa, and normal eye function. Riboflavin is found in milk products, green leafy vegetables, and eggs. Other good sources of vitamin B2 are the organ meats, heart, kidney, and liver.

-Niacin (B3) is necessary for normal growth and skin health, normal functioning of the stomach and intestines, nervous and circulatory systems, and for carbohydrate, fat, and protein metabolism. The best sources are meat, liver, poultry, and peanuts.

-Pyridoxine (B6) is necessary for fat, carbohydrate, and protein metabolism, and is sometimes used to treat nausea in pregnancy. Sources include liver, yeast, wheat germ, pork, potatoes, and milk. Vitamin B6 is usually prescribed with Isonizid (INH) treatment since INH often causes a pyridoxine deficiency.

-Cyanocobalamin (B12) is necessary for the health of nervous tissue and assists in iron metabolism and the maturation process of red blood cells. B12 is used to prevent pernicious anemia. The best sources are liver and kidneys, milk, eggs, fish, and cheese.

See Appendix IV for more information on vitamins.