Water and the Minerals Chapter 08

Why Is Water Essential to Life? Most abundant molecule in the body Rarely a pure substance Contributes to physiological functions Universal solvent Helps regulate body temperature

Why Is Water Essential to Life? Distribution of water Lean tissue retains more water Physical fitness Men generally have greater water volumes Fluid compartments Intracellular Extracellular Intercellular Intravascular

Fluid Compartments

Why Is Water Essential to Life? Water balance Solute Substance dissolved in a fluid Osmosis Intracellular and extracellular solute concentrations

Osmosis

Why Is Water Essential to Life? Functions Reactions Hydrolysis Breaking of bond with use of water Condensation Production of water through reaction Solvent Transport medium Lubricant

Why Is Water Essential to Life? Functions Body temperature regulation Sweating Evaporative cooling Dehydration Impairs body’s ability to regulate temperature

Why Is Water Essential to Life? Dehydration Early stages Complications At-risk populations Children and the elderly Athletes Body’s response Water intake Expelling water

Daily Water Balance

Why Is Water Essential to Life? Dehydration Restoring fluid balance Antidiuretic hormone High extracellular fluid solute concentration Stimulates water conservation Aldosterone Low blood pressure Reduces solutes eliminated in urine

Regulation of Blood Volume and Solute Concentration

Why Is Water Essential to Life? Recommended intake Men vs. women Foods Beverages Caffeinated beverage Physical activity Sports drinks vs. water

What Are Minerals? Inorganic substances other than water Micronutrients All are essential Cannot be created or destroyed Classification Major minerals Seven Trace minerals Eight

What Are Minerals? Diverse roles Structural roles Functional roles Physiological functions Enzyme activation Cofactor Metalloenzyme Other roles

What Are Minerals? Minerals in food Plant-based foods Animal-based foods Location influences mineral content Food processing influences mineral content Drinking water Hard water

What Are Minerals? Mineral availability Mineral levels Storage Absorption and excretion of minerals Storage Toxicity is rare Supplements Factors influencing bioavailability

What Are Minerals? Calcium Major mineral Essential roles Most abundant mineral in body Skeleton Essential roles Coagulation Muscle and nerve function Energy metabolism

What Are Minerals? Calcium Structural role Hydroxyapatite Magnesium and fluoride Bone remodeling Osteoblast Osteoclast

Bone Remodeling

What Are Minerals? Calcium Regulatory functions Blood clot formation Muscle contraction Nerve impulses Cofactor for several enzymes Healthy vision Blood glucose regulation Cell division

What Are Minerals? Calcium Hormonal regulation of blood calcium Calcitriol Increases calcium absorption and reduces excretion Parathyroid hormone Calcitonin Elevated blood calcium levels

Regulation of Blood Calcium

What Are Minerals? Calcium Bone health Peak bone mass Osteopenia Osteoporosis Kyphosis Causes for decline in bone mass Risk factors for osteoporosis Lifestyle vs. biological factors

Changes in Bone Mass during the Life Cycle

What Are Minerals? Calcium Sources Recommended intakes Dietary Fortification Supplements Take with meal Hip fracture risk Recommended intakes Bioavailability

Good Sources of Calcium

What Are Minerals? Electrolytes: sodium, chloride, & potassium Most abundant electrolytes in the body Nerve impulse & muscle contraction Fluid balance Nerve impulses Balance of ions shift across membranes Positive ions inside – potassium Negative ions outside – chloride

What Are Minerals? Electrolytes: sodium, chloride, & potassium Blood pressure regulation Blood volume decreases, blood pressure decreases Kidneys retain sodium Renin-angiotensin-aldosterone system

Regulation of Blood Volume and Blood Pressure

What Are Minerals? Electrolytes: sodium, chloride, & potassium Electrolyte balance Concentrations in blood are regulated by kidneys Low blood sodium levels Causes Hyponatremia Potassium deficiency Hypokalemia

What Are Minerals? Electrolytes: sodium, chloride, & potassium Dietary sources Sodium and chloride Potassium Sodium chloride increases blood pressure Hypertension Salt-sensitive

Good Sources of Sodium

Good Sources of Potassium

What Are Minerals? Electrolytes: sodium, chloride, & potassium AI for sodium Dietary Guidelines for Americans AI for chloride AI for potassium No UL

What Are Minerals? Phosphorus Major mineral Structural roles Examples Functional roles Blood concentration regulation Calcitriol, PTH, and calcitonin

What Are Minerals? Phosphorus Primary role in body Component of cell membranes Transport of lipids in body Protein synthesis Energy metabolism Other roles

What Are Minerals? Phosphorus Dietary sources Bioavailability Phytates Deficiency Rare Recommended intakes RDA; UL

Good Sources of Phosphorus

What Are Minerals? Magnesium Major mineral Roles Regulation Bones Chemical reactions DNA and RNA metabolism Regulation Small intestine and kidneys

What Are Minerals? Magnesium Dietary sources Deficiency Toxicity Whole-grain foods Deficiency Rare Toxicity Symptoms Recommended intakes RDA; UL

Good Sources of Magnesium

What Are Minerals? Sulfur Component of certain amino acids Structural rigidity to proteins Component of certain B vitamins Thiamin and biotin Dietary sources No published values for sulfur Protein recommendations

What Are Trace Minerals? Dietary sources Plant-based foods Animal-based foods Bioavailability Deficiencies and toxicities Rare Exceptions Absorbed primarily in small intestine Most do not exist in their free forms

What Are Trace Minerals? Iron Most common micronutrient deficiency in U.S. and around the world Functions in the body Oxygen-carrying molecules Hemoglobin Myoglobin Other roles

What Are Trace Minerals? Iron Bioavailability Type of iron consumed Heme iron and nonheme iron Other dietary components Vitamin C; meat factor; phytates; polyphenols Individual’s iron status

What Are Trace Minerals? Iron Absorption Homeostatic mechanism regulation Transport Transferrin Storage Ferritin Liver, skeletal muscle, and bone marrow cells

Effect of Iron Status on Iron Absorption

What Are Trace Minerals? Iron Deficiency Needs increase during growth and development High-risk groups Mild deficiency Severe deficiency Microcytic, hypochromic red blood cells Hematocrit

What Are Trace Minerals? Iron Overload and toxicity Acute iron toxicity Signs and symptoms Hemochromatosis Genetic abnormality Diagnosed generally in middle age Men vs. women

What Are Trace Minerals? Iron Dietary sources Recommended intakes RDA UL Special recommendations Vegetarians Endurance athletes Supplementation

Good Sources of Iron

What Are Trace Minerals? Copper Cofactor for nine enzymes in redox reactions Two distinct charged states Cupric form (CU2+) Cuprous form (CU1+) Bioavailability Iron Antacids

What Are Trace Minerals? Copper Absorbed in small intestine Circulates in blood Ceruloplasmin Storage Bile Roles Superoxide dismutase

What Are Trace Minerals? Copper Deficiency Rare Signs and symptoms Toxicity Dietary sources Recommended intakes

Good Sources of Copper

What Are Trace Minerals? Iodine Component of thyroid hormones Roles of thyroid hormones Bioavailability Thyroxine (T4) Triiodothyronine (T3) Goitrogens Absorption Thyroid stimulating hormone (TSH)

Regulation of Iodine Uptake by the Thyroid Gland

What Are Trace Minerals? Iodine Deficiency Worldwide problem Iodine deficiency disorders (IDD) Cretinism Goiter Toxicity Hypothyroidism Hyperthyroidism

What Are Trace Minerals? Iodine Dietary sources Iodine content of soil and water Table salt Recommended intakes RDA UL

Good Sources of Iodine

What Are Trace Minerals? Selenium Roles Redox reactions Thyroid function Activation of vitamin C Bioavailability Absorption is not regulated Selenoproteins Kidneys regulate blood concentrations

What Are Trace Minerals? Selenium Dietary sources Deficiency Keshan disease Toxicity Signs and symptoms Recommended intakes RDA; UL

Good Sources of Selenium

What Are Trace Minerals? Chromium Roles Insulin function Muscle mass Bioavailability Vitamin C and acidic medications Absorption Little is absorbed Simple sugars

What Are Trace Minerals? Chromium Deficiency Hospitalized patients Signs and symptoms Toxicity Supplements Dietary sources Recommended intakes AI; no UL

What Are Trace Minerals? Manganese Roles Cofactor for metalloenzymes Other roles Deficiency is rare Toxicity Absorption Dietary sources Recommended intakes

What Are Trace Minerals? Molybdenum Cofactor for several metalloenzymes Protein metabolism Sulfur-containing amino acids Gene metabolism Building block for DNA Detoxification of drugs in the liver Absorption in intestine

What Are Trace Minerals? Molybdenum Dietary sources Soil content Deficiency Rare Characteristics Toxicity Recommended intakes RDA; UL

What Are Trace Minerals? Zinc Roles Gene expression Immune function Cell growth Cofactor in more than 300 metalloenzymes Effects of inadequate dietary intake

What Are Trace Minerals? Zinc Bioavailability Animal- vs. plant-based foods Absorption Proteins Metallothionine

What Are Trace Minerals? Zinc Dietary sources Deficiency Signs and symptoms Secondary deficiency Acrodermatitis enteropathica Toxicity Excessive supplementation Recommended intakes

What Are Trace Minerals? Fluoride Not essential to any body function Strengthens bones and teeth Structurally and topically Bioavailability Dietary sources Toxicity Fluorosis Recommended intakes

What Are Trace Minerals? Are there other important trace minerals? No RDAs Some have ULs Nickel Aluminum Silicon Vanadium Arsenic Boron

Good Sources of Zinc