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Water and Minerals

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Chapter 8:

Chapter 8 Water and Minerals Copyright © 2012, 2007 Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 1

LEARNING OBJECTIVES :

LEARNING OBJECTIVES 1. List the functions and sources of water in the body. 2. Identify the regulatory mechanisms for water intake, excretion, and distribution in the body. 3. Identify the broad functions minerals serve in the body. 4. Describe functions of major and trace minerals and list dietary sources of each. 5. Describe the functions and dietary sources of electrolytes. 2

Water:

Water Food sources Fluids, fruits, vegetables Body can not survive without water/hydration AI (Adequate Intake) about 13 cups men; 9 cups women per day Coffee, tea and alcohol contain water, act as diuretics 3

Water, cont’d:

Water, cont’d Water quality Hard water contains high mineral level such as calcium and magnesium Soft water filtered with sodium to reduce mineral levels Health issues Contamination: industrial and bacterial pollution Public health concerns 4

Water as a Nutrient in the Body:

Water as a Nutrient in the Body Structure: intracellular, extracellular, and interstitial fluids Digestion and absorption Most absorbed in small intestine; Remainder regulated by colon Metabolism Not metabolized, but integral component of metabolic processes 5

Function of Water:

Function of Water Structural component of cells Regulation of body temperature Lubricant Shock-absorber: cushions body tissues Solvent for transport of nutrients and waste Source of trace minerals 6

Regulation of Fluid/Water in the Body:

Regulation of Fluid/Water in the Body Water comprises 50% to 60% of adult weight Percentages even higher for infants (75% to 80%) Homeostasis: maintained by thirst mechanism and reaction to solute levels. Excretion controlled by kidneys, brain, pituitary, and adrenals Hormones: antidiuretic hormone, aldosterone Renin-angiotensin system 7

Water, cont’d:

Water, cont’d Thirst stimulates desire to drink Thirst mechanism controlled by hypothalamus As water level in body gets low, sodium and solute levels in blood increase Causes water to be drawn from salivary glands to provide more fluid for blood Mouth then feels dry because less saliva produced If thirst mechanism faulty, hormonal mechanisms conserve water by reducing urine output 8

Minerals:

Minerals Mineral categories 16 essential minerals divided into two categories: major and trace minerals Based on amount of mineral in body Major minerals Required daily 100 mg or higher Trace minerals Required daily less than or equal to 20 mg 9

Major Minerals Calcium:

Major Minerals Calcium Function- Structure and storage (99% in bones) Regulation Calcium homeostasis: bones release calcium; intestines absorb more calcium; kidneys retain more calcium Hormonal actions: parathormone, calcitriol, calcitonin Effects of low/high blood calcium levels: calcium rigor (stiff muscles), calcium tetany (muscle spasms) 10

Calcium, cont’d:

Calcium, cont’d Recommended intake and sources AI adults to age 50: 1000 mg; AI for adults ≥50: 1200 mg; AI during pregnancy/lactation: 1000 mg Sources: dairy products (milk and milk-based products, egg yolks; leafy greens; grains; fortified foods (orange juice); legumes; tofu processed with calcium Lactose intolerance calcium strategies 11

Calcium, cont’d:

Calcium, cont’d Deficiency Affects bone health; Neurologic, cardiac Osteoporosis: Modifiable risk factors: nutrition/calcium intake, alcohol, smoking, caffeine, sedentary lifestyle Toxicity: UL 2500 mg Supplement concerns May cause: constipation; urinary stone formation; reduced absorption of iron, zinc, and other minerals 12

Phosphorus:

Phosphorus Function 85% in bones and teeth 15% for energy transfer, genetic material, acid-base buffer, phospholipids Recommended intake and sources RDA 700 mg Sources: widely available in foods, especially protein-rich foods, soft drinks Deficiency: unknown Toxicity: UL 4000 mg Excessive phosphorus, usually from supplements, causes calcium excretion 13

Magnesium:

Magnesium Function Structural and storage function in bones, catalyst for enzymes; regulates nerve and muscle function, including heart, blood clotting Recommended intake and sources RDA 420 mg male; 320 mg female Sources: Unprocessed foods, whole grains, legumes, leafy green vegetables, broccoli Deficiency Secondary causes: excessive vomiting and diarrhea, GI disorder, kidney disease, alcoholism, malnutrition Symptoms: muscle twitching and weakness, convulsion Toxicity: UL 350 mg (nonfood sources) Rare but serious 14

Sulfur:

Sulfur Function Component of protein structures Recommended intake and sources No DRI established Sources: all protein-containing foods Deficiency: Does not occur Toxicity: Not a health issue 15

Electrolytes: Sodium, Potassium, and Chloride:

Electrolytes: Sodium, Potassium, and Chloride Electrolytes Minerals circulating in blood and other body fluids that carry electrical charge Maintaining electrolyte balance important Effect on body processes such as water amount in body, blood pH, and muscle action Travel in blood as acids, bases, and salts 16

Electrolytes: Sodium, Potassium, and Chloride, cont’d:

Electrolytes: Sodium, Potassium, and Chloride, cont’d Major electrolytes: sodium, potassium, chloride As electrolytes, specific functions Acid-base balance of body fluids depends on regulated distribution of these minerals, proteins, and other electrolytes Role in normal functioning of nerves and muscles Each mineral serves other specific functions in body 17

Sodium :

Sodium Function Maintenance of blood pressure and volume Transmission of nerve impulses Fluid balance Recommended intake and sources AI 1500 mg/day sodium or about 3/4 tsp salt (sodium chloride) Sources: Table salt (sodium chloride); processed foods; occurs naturally in some foods 18

Sodium, cont’d:

Sodium, cont’d Deficiency Caused by dehydration and/or excessive diarrhea Symptoms: headache, muscle cramps, weakness, reduced ability to concentrate, memory and appetite loss Hyponatremia Toxicity: UL 2300 mg sodium Sodium-sensitive hypertension and edema 19

Potassium:

Potassium Function Primary intercellular cation maintains fluid levels inside the cells,Normal function of nerves and muscles (heart) Recommended intake and sources AI 4700 mg Sources: unprocessed foods, potatoes, tomatoes, bananas, oranges, other fruits, vegetables, dairy products, and legumes Deficiency Causes: dehydration from vomiting or diarrhea, diuretics, and misuse of laxatives Symptoms: muscle weakness, confusion, appetite loss and, in severe cases, cardiac dysrhythmias Toxicity Caused by dehydration or supplement use Symptoms: muscle weakness, vomiting, and, at excessively high levels, cardiac arrest 20

Chloride:

Chloride Function Extracellular anion maintains fluid inside/outside cells Component of hydrochloric acid in gastric juice Recommended intake and sources AI 2300 mg adults Sources: table salt (sodium chloride), foods with sodium Deficiency Very rare Toxicity Imbalance cause by dehydration 21

Trace Minerals Iron:

Trace Minerals Iron Function Distributes oxygen: component of hemoglobin (in red blood cells) and (myoglobin in muscle cells) antibody production Recommended intake and sources RDA 8 mg men; 18 mg women; 27 mg during pregnancy Iron recycled and reusedAnimal (heme) and plant (nonheme) sources: Lost through shedding tissue; cells in urine, sweat, bleeding Heme iron (easier to absorb): meat, fish, poultry Nonheme iron: vegetables, legumes, dried fruits, whole and enriched grains Factors favoring iron absorption Consuming dietary iron with foods containing ascorbic acid (vitamin C) 22

Iron, cont’d:

Iron, cont’d Deficiency: U.S. public health problem Common among women of childbearing age, teenage girls Iron deficiency anemia: a microcytic anemia Causes: internal loss of blood (i.e. bleeding ulcers, hemorrhoids, menses); lack of dietary intake (chronic dieting,) Toxicity Hemosiderosis; hemochromatosis Symptoms: liver/heart damage, diabetes, arthritis, skin discoloration At risk for iron overload: men; individuals with chronic alcohol consumption or genetically at-risk Accidental iron poisoning: children 23

Zinc:

Zinc Function More than 200 enzymes depend on zinc Growth process, taste and smell, healing process, immune system, carbohydrate metabolism Recommended intake and sources RDA 11 mg men; 8 mg woman; 11 to 12 mg during pregnancy and lactation Sources: meat, fish, poultry, whole grains, legumes, and eggs 24

Zinc, cont’d:

Zinc, cont’d Deficiency Symptoms: impaired growth and wound healing; reduced appetite result in dwarfism and hypogonadism (reduced function of gonads) At-risk in U.S., “picky” eaters; older adults Toxicity: UL 40 mg Excess supplementation produces GI distress leading to vomiting and diarrhea, fever, exhaustion (similar to flu) Continual excessive use decreases iron and copper levels; reduces HDL 25

Iodine:

Iodine Function Part of hormone thyroxin produced by thyroid gland Recommended intake and sources RDA100- 150 mcg adults Sources: Salt fortified with iodine (check label); seafood; other sources inconsistent Deficiency Reduces thyroxine production Deficiency during pregnancy causes cretinism of fetus Goiter Lack of dietary iodine Toxicity: UL 1100 mcg Thyrotoxicosis: iodine-induced goiter 26

Fluoride:

Fluoride Function Increases resistance to tooth decay and part of tooth formation Bone mineralization for skeletal health Recommended intake and sources AI 4 mg men; 3 mg women Sources: fluoridated water (where available), tea, seafood, seaweed; other sources vary Toothpaste ingestion Deficiency Increase risk of dental caries and may alter bone health Toxicity: UL 10 mg Fluorosis 27

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