CH. 8 Key Concepts

Describe the functions of the seven major minerals, their food sources, and the effects of their deficiencies and toxicities. (Part 1)

Calcium is the chief mineral of bones and teeth. Calcium plays roles in nerve transmission, muscle contraction, and blood clotting. Calcium absorption adjusts somewhat to dietary intakes and altered needs. Phosphorus is abundant in bones and teeth. Phosphorus helps maintain acid-base balance, is part of the genetic material in cells, assists in energy metabolism, and forms part of cell membranes. Phosphorus deficiencies are unlikely. Magnesium stored in the bones can be drawn out for use by the cells. Magnesium is a shortfall nutrient in the U.S. population. Sodium is the main positively charged ion outside the body's cells. Sodium attracts water.

Describe the concepts of fluid and electrolyte balance and acid-base balance and their importance to health.

Cells regulate water movement by pumping minerals across their membranes; water follows the minerals. Mineral salts form electrolytes that help keep fluids in their proper compartments. Minerals act as buffers to help maintain body fluids at the correct pH to permit life's processes.

Itemize food choices that help to meet the need for calcium.

Food choices that are significant sources of calcium include milk and milk products, calcium-fortified milk alternatives, oysters, small boney fish, calcium-set tofu, certain leafy green vegetables (i.e., kale, bok choy, turnip greens), and broccoli.

Compare the types and safety of drinking water from different sources.

Hard water is high in calcium and magnesium. Soft water is high in sodium, and it dissolves cadmium and lead from pipes. Public drinking water is tested and treated for safety, and with rare exceptions, systems are properly maintained. Bottled water is also tested, but single-use bottles create a disposal problem.

Discuss the functions of the nine known trace minerals, their food sources, and the effects of their deficiencies and toxicities. (Part 1)

Iodine is part of the hormone thyroxine, which influences energy metabolism. Iodine deficiency diseases are goiter and cretinism. Large amounts of iodine are toxic. Most people in the United States meet their need for iodine. Most iron in the body is in hemoglobin and myoglobin or occurs as part of enzymes in the energy-yielding pathways. Iron absorption is regulated by the hormone hepcidin; absorption is affected by promoters and inhibitors in foods. Iron-deficiency anemia is a problem among many groups worldwide. Too much iron is toxic. Zinc acts as a cofactor for hundreds of enzymes in protein, fat, and carbohydrate metabolism. Zinc plays roles in digestion, protein synthesis, cell division, and vision. Zinc deficiency impairs many vital body functions.

Describe the functions of the seven major minerals, their food sources, and the effects of their deficiencies and toxicities. (Part 2)

Too much dietary sodium raises blood pressure; few diets lack sodium. Potassium, the major positive ion inside cells, plays important vitals roles in maintaining fluid and electrolyte balance and cell integrity. Americans take in too few potassium-rich fruits and vegetables. Potassium excess can be toxic. Chloride is the body's major negative ion, is responsible for stomach acidity, and assists in maintaining proper body chemistry. No known diet lacks chloride. Sulfate is a necessary nutrient used to synthesize sulfur-containing body compounds.

Explain the functions of water and the importance of maintaining the body's water balance.

Water makes up about 60 percent of the body's weight. In the body, water transports, dissolves, and reacts with chemicals; provides lubrication and shock protection; and aids in temperature regulation. The body employs numerous tactics to balance water intake and output to maintain its water balance. A change in the body's water content can bring about a temporary change in body weight. Water losses from the body must be balanced by water intakes to maintain hydration. The brain regulates water intake; the brain and kidneys regulate water excretion. Dehydration and water intoxication can arise with deficient or excessive water intake. Many factors influence a person's need for water. Water is provided by beverages and foods and by cellular metabolism. Sweating increases fluid needs. High-calorie beverages affect daily calorie intakes.

Describe how osteoporosis develops and the actions that may help to prevent it.

While osteoporosis typically occurs later in life, it develops silently as a result of insufficient dietary calcium, vitamin D, and load bearing physical activity. Age, gender, and genetic predisposition are also factors. Consuming nutrients that help build strong bones, such as vitamin D and calcium, helps prevent or delay the onset of osteoporosis later in the life.

Discuss the functions of the nine known trace minerals, their food sources, and the effects of their deficiencies and toxicities. (Part 2)

Zinc supplements can interfere with iron absorption and can reach toxic doses. Zinc in foods is nontoxic. Selenium works with an enzyme system to protect body compounds from oxidation. Deficiencies are rare in developed countries, but toxicities can occur from overuse of supplements. Fluoride stabilizes bones and makes teeth resistant to decay. Excess fluoride discolors teeth and weakens bones; large doses are toxic. Chromium is needed for normal blood glucose regulation. Whole, minimally processed foods are the best chromium sources. Copper is needed to form hemoglobin and assists in many other body processes. Copper deficiency is rare. Many different trace elements play important roles in the body. All of the trace minerals are toxic in excess.