Chapter 8 Water and Minerals Nutrition: Concepts & Controversies, 12e Sizer/Whitney

Water Makes up about 60 percent of a person’s weight Roles Solvent (not universal) Carries nutrients throughout the body Cleansing agent Lubrication and cushion Coolant Participates in chemical reactions

Body’s Water Balance Water balance Dehydration Signs: Thirst and fatigue Water intoxication Thirst and satiety govern water intake Hypothalamus, pituitary gland, kidneys

Water Balance – A Typical Example

Effects of Mild Dehydration, Severe Dehydration, and Chronic Lack of Fluid

How Much Water Do I Need to Drink in a Day? Water needs vary Influential factors: foods, air temp and humidity, altitude, activity level (Table 8-2) Fluids and foods DRI: 9-13 cups Sweating = increased water needs Choosing fluids Less carbonated, sweetened, caffeinated and alcoholic beverages (diuretics)

Factors That Increase Fluid Needs

Water in Foods and Beverages

Body Fluids and Minerals Water follows salt Electrolytes Water flows toward greater concentration Fluid and electrolyte balance Causes of imbalance Acid-base balance Hydrogen Buffers

How Electrolytes Govern Water Flow Fig. 8-4

Minerals in a 60-Kilogram (132-Pound) Person, in Grams

Calcium Most abundant mineral in the body Meeting DRI recommendations: 1000 mg/day (19-50), 1200 mg/day (>51) Storage facilities Bones In constant flux Teeth

Calcium In body fluids Calcium balance 1 percent of body’s calcium Roles: nerve transmission, blood pressure, blood clotting, muscle contraction and heartbeat Calcium balance Skeleton serves as a calcium bank Increased need for calcium Intestines increase absorption, bones release calcium, kidneys prevent loss through urine

Calcium Bone loss Inevitable consequence of aging Peak bone mass: 12-30 years (Figure 8-8) Osteoporosis: porous bone Food sources better than Supplements

Bone Throughout Life Fig. 8-8

Calcium

Meeting the Need for Calcium Table 8-9

Phosphorus

Magnesium

Sodium Roles Deficiency: none “Water Weight” Major part of fluid and electrolyte balance Acid-base balance Deficiency: none “Water Weight” Water follows sodium Increase sodium = increase water weight

Sodium and Salt Intake Guidelines

Sodium Blood pressure Hypertension Measures: 140/90, Pre: 130/90, Ideal 120/80 Salt-sensitive hypertension Sodium intake increases blood pressure Heart damage DASH diet: more fruits, veggies, whole grains, low sodium Controlling salt intake: saltshaker and read food labels

Sources of Sodium in the U.S. Diet

Potassium

Chloride and Sulfate Chloride Sulfate Crucial for fluid balance (chief – charged ion). Hydrochloric acid Principle food source: salt Sulfate Roles: make up rigid proteins like hair, nails, and skin (sulfur-containing) No recommended intake Deficiencies are unknown

Iodine Body’s work is done by iodide Roles Deficiency Toxicity: Goiter Thyroxine: hormone that regulates basal metabolism Deficiency Goiter Cretinism Toxicity: Goiter Food sources: Iodized salt and seafood

Iron Every living cell contains iron Two proteins Roles Hemoglobin Myoglobin Roles Hold, Carry, and Release oxygen Make new cells, amino acids, hormones, & neurotransmitters

Iron Iron stores Absorbing iron (promoters and inhibitors) A mineral to be hoarded Iron losses: blood loss Special proteins transport and store iron Absorbing iron (promoters and inhibitors) Only 10-15% is absorbed (oxidant) Forms of iron in food: heme vs. non-heme MFP factor: promotes absorption Impairing iron absorption: tannins, phytates

Iron Causes of deficiency Groups most susceptible to deficiency Inadequate intake, high-calorie foods high in refined carbs, blood loss Groups most susceptible to deficiency Women of childbearing age Infants and toddlers Adolescents Too much iron (Toxicity) Iron overload: absorb too much iron

Promoters and Inhibitors of Iron Absorption

Iron Deficiency Iron deficiency Iron-deficiency anemia Signs of deficiency

Normal and Anemic Blood Cells Fig. 8-7

Iron

Zinc

Selenium Roles in the body: metabolism regulation and antioxidant Relationship with chronic disease Specific type of heart disease Lead to selenium being placed on essential nutrient list Toxicity: hair loss, diarrhea, and nerve abnormalities Supplements Sources: widely spread in foods

Fluoride Not essential to life Roles in the body Deficiency Toxicity Protects enamel Deficiency Dental decay Toxicity Fluorosis Sources : drinking water

Chromium and Copper Chromium Copper Helps with insulin Sources: unrefined foods Copper Form hemoglobin and collagen Deficiency: Impair immunity and blood flow in the arteries

Osteoporosis: Controversy 8 Read Controversy 8 at the end of the chapter Describe a diet that a young woman can follow to help prevent osteoporosis in later life