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Chapter 8 Water & Minerals:
The Ocean Within
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Water: Crucial to Life
Water is the most essential nutrient
45–75% body weight
Body water
2/3 Intracellular
1/3 Extracellular
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Water: Crucial to Life
Electrolytes and water
Balanced inside and outside cells
Cation
Anions
Osmosis
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Intake Recommendations
How much water is enough?
Men = 3.7 liters/day AI
Women = 2.7 liters/day AI
Pregnancy = 3.0 liters/day AI
Lactation = 3.8 liters/day
Increased needs for activity and sweating
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Intake Recommendations
Sources
75-80% from Beverages
20-25% from Foods
Small amount from metabolic reactions
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Intake Recommendations
Where Does the Water Go?
Insensible water losses
Continuous evaporation of water from lungs and skin
Urine
Illness
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Intake Recommendations
Water Balance
Bodies carefully maintain water balance
Hormonal effects
Antidiuretic hormone (ADH)
Aldosterone
Thirst
Alcohol, caffeine, and common medications affect fluid balance
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Intake Recommendations
Dehydration
Early signs: Fatigue, headache, and dark urine with strong odor
Water loss of 20% can cause coma and death
Seniors and infants especially vulnerable
Water consumption primary treatment
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Intake Recommendations
Water Intoxication
First causes headaches and confusion
Can then lead to seizures and death
Usually due to rapid consumption
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Minerals
Inorganic elements
Not destroyed by heat, light, acidity, or alkalinity
Micronutrients
Major minerals and trace minerals
Involved in body structure and regulation
Found in plant and animal foods
Absorption limited by several factors
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Minerals in Foods
Both plants and animal sources
Bioavailability
Body adjusts mineral absorption to our needs
Megadosing can alter absorption of other minerals
Fiber affects absorption
Major Minerals and Health
Mineral status significantly affects health
Play critical parts in hypertension and osteoporosis
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Sodium
Functions
Regulates fluid level, blood pressure, and pH
Helps transmit nerve impulses
Food Sources
Processed and convenience foods
Added (table) salt
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Sodium
Dietary Recommendations
Daily intake less than 2,400 mg/day
Daily intake less than 1,500 mg/day desirable
Dealing with Excess Sodium
Can contribute to hypertension
Can worsen dehydration
Potassium
Functions
Assists muscle contraction
Helps transmit nerve impulses
Regulates blood pressure and heartbeat
Food Sources
Unprocessed foods: fruits, vegetables, and grains
Meat, fish, poultry, and dairy products
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Potassium
Dietary Recommendations
AI: 4,700 mg/day
Deficiency
Likely factor in hypertension risk
Can disrupt acid-base balance
Toxicity
Rare
High levels can slow heart
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Chloride
Functions
Fluid balance
Hydrochloric acid (stomach acid)
Food sources
Table salt
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Chloride
Dietary Recommendations
AI: 2,300 mg/day
Can estimate chloride content based on sodium content
Chloride content = 1.5 x Sodium content
Deficiency
Excessive vomiting
Bulimics most at risk
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Calcium
Functions
Bone structure
Hydroxyapatite
Bone cells
Osteoblasts
Osteoclasts
Reserve of calcium and phosphorus
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Calcium
Functions
Muscles and metabolism
Flow of calcium causes muscles to contract or relax
Other functions
Blood clotting
Production of fibrin
Nerve impulse transmission
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Calcium
Regulation of blood calcium levels
Calcitriol
Parathyroid hormone
Calcitonin
Dietary Recommendations
RDA: 1,300 mg/day (children 9-18)
RDA: 1,000 mg/day (men 19-70; women 19-50)
RDA: 1,200 mg/day (men 70+; women 51+)
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Calcium
Food Sources
Dairy products, green vegetables, processed and fortified foods
Oxalate—binds calcium
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Calcium
Calcium Absorption
Relatively inefficient
Calcium Balance
Bone calcium used to maintain normal blood calcium levels
UL: 2,500 mg/day (adults 19-50)
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Phosphorus
Functions
Bone structure
Component of ATP, DNA,
RNA, and phospholipids
Food sources
Meat, milk, and eggs
Processed foods
Phosphate balance
Too much phosphorus and too little calcium = increased bone loss
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Magnesium
Function
Participates in more than 300 types of enzyme-driven reactions
Food sources
Whole grains, vegetables, legumes, tofu, seafood, and chocolate
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Magnesium
Deficiency
Associated with alcoholism
Also associated with chronic illnesses
Rarely occurs on its own
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Sulfur
Function
Primarily a component of organic nutrients
Food sources
Typical diets contain ample sulfur
Deficiency unknown in humans
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Trace Minerals
Cofactors for enzymes
Components of hormones
Participate in many chemical reactions
Essential for growth
Essential to the immune system
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Iron
Functions
Oxygen transport as part of hemoglobin and myoglobin
Cofactor for enzymes, immune function, and normal brain function
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Iron
Iron Absorption
Effect of Iron Status
Absorption varies
Effect of GI Function
Depends on stomach acid
Effect of the Amount and Form of Iron in Food
Conserve iron
Heme iron
Non-heme iron
Iron
Iron absorption
Dietary Factors Enhancing Iron Absorption
Vitamin C
Dietary Factors Inhibiting Iron Absorption
Phytate, polyphenols, oxalates, high-fiber foods, calcium, and zinc
Iron
Iron Transport and Storage
Transferrin ferries iron through blood
Most iron stored as ferritin in body
Smaller amounts stored as hemosiderin
Iron
Iron Turnover and Losses
Routine destruction of old red blood cells releases iron
Recycled iron used to build new red blood cells
Dietary iron especially important in times of rapid growth and blood expansion
Lose iron in feces, sweat, skin cells, and menstruation
Digestive disorders increase iron losses
Iron
Food sources
Red meat, clam, oyster, liver, poultry, fish, pork, lamb, tofu, legumes, enriched and whole grains, fortified cereal
Iron
Deficiency
Most common nutrient deficiency
Most severe stage: Iron-deficiency anemia
Lack of iron inhibits red blood cell production
Symptoms include fatigue and pale skin
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Iron
Toxicity
Accidental iron overdose leading cause of poisoning deaths in young children in US
Genetic defect: Hereditary hemochromatosis
Causes excessive iron absorption
Causes chronic iron overload
Can lead to severe organ damage and chronic disease
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Zinc
Functions
Serves as cofactor for major enzymes
Helps fold proteins into functional shapes
Helps control diverse functions, including gene expression, cell death, and nerve transmission
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Zinc
Enzymes
Helps provide structural integrity or activate catalytic ability
Gene regulation
Enables proteins to fold into a special form that interacts with DNA
Immune system
Vital to fighting infection
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Zinc
Regulation of Zinc in the Body
Absorption
Similar to iron
Only about 10-35% of zinc absorbed
Phytate inhibits absorption
Transport, distribution, and excretion
Circulates bound to protein
Zinc
Food sources
Red meats, seafood
Zinc
Deficiency
Uncommon but may occur in people with illnesses that impair absorption
Poor growth and delayed development
Toxicity
Chronic doses may induce copper deficiency
Selenium
Functions
Part of antioxidant enzyme
Thyroid metabolism and immune function
Absorption and Excretion
Bound to AA
Vitamins A, C, E enhance
Phytates inhibit
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Selenium
Food sources
Organ meats, fish, seafood, meats, Brazil nuts
Deficiency
Increases susceptibility to some infections
Toxicity
Brittle hair and nails
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Iodine
Functions
Thyroid hormone production
Food sources
Iodized salt, fish, seafood, dairy products
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Iodine
Deficiency
Goiter: enlarged thyroid gland
Cretinism: mental retardation
Occurs in fetus when pregnant woman is deficient
Toxicity
Goiter
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Copper
Functions
Melanin, collagen, and elastin production
Immune function
Antioxidant enzyme
systems
Absorption and Storage
Varies from 20% to 50%
Copper
Food Sources
Organ meats, shellfish, nuts, and legumes
Deficiency
Causes anemia and poor immune function
Toxicity
Relatively nontoxic
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Manganese
Functions
Cartilage production
Antioxidant enzyme systems
Food Sources
Tea, nuts, cereals
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Manganese
Deficiency
Some illnesses may cause suboptimal Mg status
Toxicity
Incidents due to air pollutants
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Fluoride
Functions
Bone and tooth structure
Food sources
Fluoridated water
Balance
Excess can cause fluorosis
The fluoridation debate
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Chromium
Functions
Glucose metabolism
Food sources
Mushrooms, dark chocolate, nuts, whole grains
Deficiency and toxicity
Difficult to determine deficiency
No UL
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Molybdenum
Functions
Enzyme cofactor
Food sources
Peas, beans, some breakfast cereals, and organ meats
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Other Trace Minerals and Ultratrace Minerals
Arsenic
Boron
Nickel
Silicon
Vanadium
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