CHAPTER 7 VITAMINS Vitamins are organic (carbon-containing) compounds that are essential in small amounts for body processes. Vitamins themselves do not provide energy. They enable the body to use the energy provided by carbohydrates, fats, and proteins Many of the 13 known vitamins are currently named according to their chemical composition or function in the body (Table 7-1). Since 1997, the Food and Nutrition Board of the Institute of Medicine has been establishing Dietary Reference Intakes (DRIs) to replace the Recommended Dietary Allowances (RDAs) (Table 7-2). The term avitaminosis means “without vitamins.” This word followed by the name of a specific vitamin is used to indicate a serious lack of that particular vitamin. Hypervitaminosis is the excess of one or more vitamins. Either a lack or excess of vitamins can be detrimental to a person’s health. Vitamins taken in addition to those received in the diet are called vitamin supplements. These are available in concentrated forms in tablets, capsules, and drops. Vitamin concentrates are sometimes termed natural or synthetic (manufactured). Preserving Vitamin Content in Food Buying the freshest, unbruised vegetables and fruits locally and using them raw whenever possible Preparing fresh vegetables and fruits just before serving Heating canned vegetables quickly and in their own liquid Preparing fresh vegetables and fruits just before serving Heating canned vegetables quickly and in their own liquid Covering the pan, cooking vegetables until bright in color and crisp tender Saving any cooking liquid for later use in soups, stews, and gravies Storing fresh vegetables and most fruits in a cool, dark place Microwave fruits and vegetables in 1 to 2 tablespoons of water CLASSIFICATION Vitamins are commonly grouped according to solubility. A, D, E, and K are fatsoluble, and B complex and C are water-soluble. In addition, vitamin D is sometimes classified as a hormone, and the B-complex group may be classified as catalysts or coenzymes. When a vitamin has different chemical forms but serves the same purpose in the body, these forms are sometimes called vitamers. Vitamin E is an example. Sometimes a precursor, or provitamin, is found in foods. This is a substance from which the body can synthesize (manufacture) a specific vitamin. Carotenoids are examples of precursors of vitamin A and are referred to as provitamin A FAT-SOLUBLE VITAMINS WATER-SOLUBLE VITAMINS Water-soluble vitamins include B complex and C. These vitamins dissolve in water and are easily destroyed by air, light, and cooking. They are not stored in the body to the extent that fat-soluble vitamins are stored. Vitamin B Complex Beriberi is a disease that affects the nervous, cardiovascular, and gastrointestinal systems. The legs feel heavy, the feet burn, and the muscles degenerate. The patient is irritable and suffers from headaches, depression, anorexia, constipation, tachycardia (rapid heart rate), edema, and heart failure Thiamine, a coenzyme, was originally named vitamin B1. It is partially destroyed by heat and alkalies, and it is lost in cooking water. Riboflavin is sometimes called B2. It is destroyed by light and irradiation and is unstable in alkalies Niacin is the generic name for nicotinic acid and nicotinamide. Niacin is fairly stable in foods. It can withstand reasonable amounts of heat and acid and is not destroyed during food storage Vitamin B6 is composed of three related forms: pyridoxine, pyridoxal, and pyridoxamine. It is stable to heat but sensitive to light and alkalies. Vitamin B12 (cobalamin) is a compound that contains the mineral cobalt. It is slightly soluble in water and fairly stable to heat, but it is damaged by strong acids or alkalies and by light. It can be stored in the human body for 3 to 5 years. Folate, folacin, and folic acid are chemically similar compounds. Their names are often used interchangeably. Biotin participates as a coenzyme in the synthesis of fatty acids and amino acids. Some of its best dietary sources are egg yolks, milk, poultry, fish, broccoli, spinach, and cauliflower. Biotin is also synthesized in the intestine by microorganisms, but the amount that is available for absorption is unknown Biotin participates as a coenzyme in the synthesis of fatty acids and amino acids. Some of its best dietary sources are egg yolks, milk, poultry, fish, broccoli, spinach, and cauliflower. Biotin is also synthesized in the intestine by microorganisms, but the amount that is available for absorption is unknown Vitamin C is also known as ascorbic acid. It has antioxidant properties and protects foods from oxidation, and it is required for all cell metabolism. CHAPTER 8 MINERALS A mineral is an inorganic (non-carbon-containing) element that is necessary for the body to build tissues, regulate body fluids, or assist in various body functions. Minerals are found in all body tissues. Minerals cannot provide energy by themselves, but in their role as body regulators, they contribute to the production of energy within the body. CLASSIFICATION TOXICITY Because it is known that minerals are essential to good health, some would-be nutritionists will make claims that “more is better.” Ironically, more can be hazardous to one’s health when it comes to minerals. However, when concentrated forms of minerals are taken on a regular basis, over a period of time, they become more than the body can handle, and toxicity develops. An excessive amount of one mineral can sometimes cause a deficiency of another mineral.
