Download Chapter 11: Water and the Major Minerals

Chapter 9
Lecture
Outline
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Water
 50%-70%
 Muscle
of body weight
contains 73% water
– Fat contains ~20%
 Intracellular
fluid
– Fluid within the cells
 Extracellular
fluid
– Fluid outside the cells
Fluid Balance
Water shifts freely in and out of cells
 Controlled by electrolyte concentration
 Osmosis
 Intracellular water volume

– Depends on intracellular potassium and
phosphate concentrations

Extracellular water volume
– Depends on extracellular sodium and
potassium concentrations
Functions of Water

Body temperature regulation
– Water absorbs excess heat
– Body secretes fluid via perspiration
– Skin is cooled as perspiration evaporates

Removal of body waste via urine
– Urea excretion
– Sodium excretion
– Avoid concentrated urine

Amniotic fluid, joint lubricants, saliva, bile
Are You Drinking Enough?

Fluid recommendation: 9 cups for women and
13 cups for men as a starting point
Thirst Mechanism
Not reliable
 Concerns for infants, older adults, athletes
 Athletes

– Weigh before and after training session
– Consume 3 cups for every pound lost

Illness (vomiting, diarrhea, fever)
Ignoring the Thirst Signal
Shortage of water increases fluid
conservation
 Antidiuretic hormone

– Released by the pituitary gland
– Forces kidneys to conserve water (reduce
urine flow)

Aldosterone
– Responds to drop in blood pressure
– Signals the kidney to retain sodium (water)
Hydration

Loss of 1%-2% of body weight in fluid
– Thirst signal

Loss of 2% or more of body weight causes
muscle weakness
– Lose significant strength and endurance

Loss of 10%-12%
– Heat intolerance

Loss of 20%
– Coma and death
Too Much Water
 Overburden
 Low
the kidneys
blood electrolyte concentrations
 Blurred
vision
Minerals
 Various
functions in the body
 Major Minerals
– Require >100 mg /day
– Calcium, phosphorus
 Trace Minerals
– Require < 100 mg/day
– Iron, zinc
Bioavailability of Minerals
Degree of absorption
 Presence of binders and fiber
 Animal products are better absorbed
 Plants depend on mineral content of soil
 Refinement lowers mineral content
 Mineral-mineral competition
 Vitamins-mineral competition

Mineral Toxicity
 Trace
minerals are more toxic
 Result of supplementation
– Presence of contaminants
– Look for the United States
Pharmacopeia (USP)-approved brands
Sodium
Table salt (NaCl): 40% sodium, 60% chloride
 95% of ingested sodium is absorbed
 Positive ion in extracellular fluid
 Aldosterone regulates sodium balance
 Key for retaining body water
 Excretion regulated by the kidneys
 Muscle contraction
 Conduction of nerve impulses

Sodium Deficiency
Deficiency is rare
 Persistent vomiting/ diarrhea
 Excessive perspiration

– Losing 2-3% of body weight
Depletion of sodium in the body
 Signs of deficiency:

– Muscle cramp, nausea, vomiting, dizziness, shock,
coma

Normally kidney will respond by conserving
sodium
Food Sources of Sodium
Most sodium is added by food
manufacturers and restaurants
 Milk and dairy products
 Processed foods
 Sodium content listed on the labels

Sodium Needs
Adequate Intake is 1500 mg for adults
 Body only needs 200 mg to function
 Daily Value is 2400 mg/day
 Upper Level is 2300 mg
 Typical intake is 4700 mg/day
 Sodium-sensitive individuals should restrict
intake

Potassium
Positive ion in intracelluar fluid
 Functions

– Fluid balance
– Nerve impulse transmission
Associated with lowering blood pressure
 90% of potassium consumed is absorbed
 Low blood potassium

– Muscle cramps, confusion, constipation,
irregular heart beat, heart failure
Potassium Sources and Needs
Fruits, vegetables, milk, grains, meats,
dried beans
 Adequate Intake is 4700 mg/day
 Daily Value is 3500 mg/day
 Typical intake is 2000-3000 mg/day
 Diuretics may deplete potassium
 Excess potassium is excreted by the
kidneys; no Upper Level

Chloride
 Negative
ion for extracellular fluid
 Component of
– NaCl
– Hydrochloric acid (HCl)
 Functions
– Immune response, nerve function
Chloride Needs
Excess excreted by the kidneys
 Adequate Intake is 2300 mg/day
 Daily Value is 3400 mg
 Upper Level is 3600 mg
 High Intake may cause high blood
pressure

Calcium
 99%
is in bones and teeth
 Makes
up 40% of all the minerals
present in the body
Absorption of Calcium
Amount in body is dependent on
amount absorbed
 Requires slightly acidic environment and
vitamin D
 Absorbed in upper part of small
intestine
 Normally absorb 25% of calcium in food
 Increase to ~60% during time of need
(pregnancy, infancy)
 Parathyroid hormone

Decreased Absorption of
Calcium
Rapid intestinal motility
 High fiber intake
 Excess phosphorus
 Vitamin D deficiency
 Polyphenols (tannins) in tea
 Menopause
 Aging

Blood Calcium is Regulated
 Blood
level is maintained at the price
of bone calcium
 Blood level can be maintained despite
inadequate calcium intake
 Setting stage for future bone fractures
Functions of Calcium
 Bone
formation and maintenance
 Blood clotting
 Nerve impulse transmission
 Muscle contraction
 Cell metabolism
–Activates various enzymes
Building Higher Bone Mass
Adequate diet
 Healthy body weight
 Normal menses
 Weight-bearing physical activity
 Moderate intakes of protein, phosphorus,
sodium, caffeine
 Non-smoker
 Lower use of certain medications

Other Roles of Calcium
 May
lower blood pressure
 May reduce colon cancer
 May reduce PMS symptoms
 May lower blood cholesterol
 May reduce kidney stones
 Reduces lead absorption
 Promotes weight loss?
Bone Strength
 Dependent
on bone mass and bone
mineral density
 The
more there is, the stronger the
bone
Calcium Needs
Daily Value is 1000 mg/day
 Adequate Intake is 1000 -1200 mg/day for
adults
 Adequate Intake is 1300 mg/day for
adolescents (9-18 yrs. old)
 Average intake: 800 mg/day for women
and 1000 mg/day for men
 Upper Level is 2500 mg/day

Calcium Supplements
Recommended for people who cannot
incorporate Ca into their diets
 Not recommended with high-zinc meal
 Calcium carbonate (40% calcium)

– For those with ample stomach acid
– Found in antacids

Calcium citrate (21% calcium)
– Enhances absorption due to acidity content
– Recommended for older adults
Phosphorus
Major ion of intracellular fluid
 Bone and tooth strength
 Component of various compounds

– ATP, cell membrane, enzymes, DNA





Role in acid/base balance
Absorption is based on body’s need (70%-90%)
No disease associated with deficiency
May contribute to bone loss in older women
Vitamin D enhances absorption
Phosphorus Sources and Needs








Wide variety of foods
Dairy, bakery products, eggs, sodas, meats
Some from food additives
Difficult to limit intake
RDA is 700 mg/day for adults
Daily Value is 1000 mg
Current intake exceeds RDA
Deficiency unlikely
Phosphorus Toxicity

Problem for individuals with inefficient
kidney function

Phosphate ions bind calcium
– Chronic imbalance may lead to bone loss

Upper Level is 3-4 g/day
Magnesium

Absorption based on body’s needs
(normally 40%-60%)

Kidneys regulate blood concentration of
magnesium

60% is stored in the bones
Functions of Magnesium
Aids in many enzyme reactions
 Potassium and calcium metabolism
 Proper nerve and cardiac functions
 Insulin release from the pancreas
 May dilate arteries

– Decrease blood pressure

May prevent heart rhythm abnormalities
Magnesium Deficiency

Develops slowly

Irregular heartbeat

Weakness, muscle spasms, disorientation,
nausea, vomiting, seizures
Too Much or Too Little
Magnesium

Magnesium loss
– Heavy perspiration
– Long-standing diarrhea or vomiting
– Alcoholism
– Disorientation, weakness, muscle pain,
poor heart function

Toxicity
– Caused by medications
Magnesium Sources and Needs
Whole grains, vegetables, nuts, seeds
 Hard tap water
 Dairy, chocolate, meat
 RDA for women is 310 mg/day
 RDA for men is 400 mg/day
 Daily Value is 400 mg
 Average intake is lower than the RDA
 Upper Level is 350 mg (nonfood source)

Sulfur
Found in amino acids and vitamins
 Acid-base balance
 Drug detoxifying pathways
 Part of a natural diet, primarily from
protein
 Used to preserve foods
 No deficiency or toxicity

The Trace Minerals
Needed in much smaller amounts
 Essential for health
 Difficult to study

– Only trace amounts in the body

Animal sources of mineral are generally
better absorbed
Iron
Found in minute amounts in every cell
 18% is absorbed
 Heme iron vs. Nonheme iron

– Heme found in animal products better
absorbed than nonheme
– Meat protein factor may aid in nonheme
absorption

Vitamin C enhances absorption (nonheme
iron)
Absorption of Iron
 Determined
by body’s need
 Iron storage in intestinal cells
 Absorbed in an acidic environment
 Hindered by phytic acid, oxalic acid,
high fiber, high calcium, polyphenols
Functions of Iron

Hemoglobin in red blood cells
– Transports oxygen and carbon dioxide
– High turnover, high demand for iron
Myoglobin in muscle cells
 Electron transport chain
 Enzyme cofactor
 Immune function
 Drug-detoxification pathway

Iron-Deficient Anemia
Most common form of anemia
 Low levels of hemoglobin and
hematocrit
 Insufficient intake and stores
 Reduction in

– Production of red blood cells
– Oxygen-carrying capacity
Iron Deficiency Anemia

Most at risk:
– Infant, toddler, chronic blood loss, vegans,
runners, and women of childbearing years
– Pica in women and children

Signs:
– Paleness, brittle nails, fatigue, poor
temperature control, poor growth
Iron Needs
RDA is 8 mg/day for adult male
 RDA is 18 mg/day for female age 19 to 50
 Daily Value is 18 mg
 Average intake exceeds RDA for men; low
for some women
 Upper Level is 45 mg/day

Iron Toxicity
Serious, especially for children
 Signs:

– Diarrhea, constipation, nausea, abdominal pain
– Causes death due to respiratory collapse (shock)

Hemochromatosis
– Genetic disease
– Iron deposit that can lead to organ damage
– May go undetected until organ damage at 50-60
Zinc

Absorption
– Influenced by the foods consumed
– Animal sources are better absorbed
– Dependent on body’s need

Factors that decrease absorption
– Presence of phytic acid
– Competes with copper and iron for absorption
Functions of Zinc








Cofactor to many enzymes
DNA synthesis and function
Growth, protein metabolism, wound healing
Immune function
Cell membrane structure and function
Development of sexual organs and bones
Insulin function
Component of superoxide dismutase
Zinc Needs
RDA 8 mg for adult female
 RDA 11 mg for adult male
 Daily Value is 15 mg
 Average intake meets RDA
 Upper Level is 40 mg/day

Zinc Toxicity
 Inhibits
copper metabolism
 Possibly increases risk for prostate
cancer
 Causes diarrhea, cramps, nausea,
vomiting
 Depresses immune function
Selenium
Readily absorbed
 Excreted through the urine and feces
 Functions:

– Co-factor for glutathione peroxidase
– Protects the heart and other cells from
oxidative damage
– Works together with vitamin E
– Aids in cancer prevention?

Thyroid hormone metabolism
Selenium Deficiency
 Muscle
pain
 Muscle wasting
 Weakness
 Deterioration of heart muscle
Selenium Sources and Needs
 Fish,
meat (organ meats), egg, milk,
shellfish
 Grains, seeds, nuts (dependent on soil
content)
 RDA
for adults is 55 µg/day
 Daily Value is 70 µg
 Average intake exceeds RDA (and
Daily Value)
Selenium Toxicity
Upper Level is 400 µg/day
 Garlicky breath
 Hair loss
 Nausea, vomiting
 Weakness
 Rashes
 Cirrhosis of the liver

Iodide
Iodine in foods–fortified salt
 Functions:

– Supports thyroid hormone synthesis
– Regulates metabolic rate, growth, development

Deficiency:
– Thyroid gland enlarges (goiter) due to low
intake
– Cretinism, stunting of fetal growth and
mental development as a result of low iodide in
maternal diet
Iodide Sources and Needs
Iodized salt ̶ ½ tsp. meets RDA
 Saltwater fish, seafood, dairy, grains
 Sea salt is poor source

– Iodide lost during processing
Plant source dependent on soil content
 RDA and Daily Value are 150 µg/day

– Only 50 µg needed to prevent goiter

Average intake exceeds RDA
Iodide Toxicity
Upper Level is 1.1 mg/day
 Thyroid hormone synthesis is inhibited
 “Toxic goiter” results
 Consumption of seaweed poses risk

Copper
 Aids
in iron metabolism
 Absorption:
– Dependent on body’s needs
– Decreases with high intakes of vitamin
C, phytic acid, fiber, zinc, iron, certain
amino acids
Functions of Copper
 Increases
iron absorption
 Aids in formation of connective tissue
 Found in superoxide dismutase
 Assists immune system, blood
clotting, brain development,
cholesterol metabolism
Copper Deficiency
 Anemia
 Decreased
 Bone
WBC
loss
 Inadequate growth
Copper Sources and Needs
 Organ
meats, seafood, cocoa
 Mushrooms, legumes, seeds, nuts,
whole grains
 RDA is 900 µg/day for adults
 Daily Value is 2 mg
 Average intake is near the RDA
 Upper Level is 10 mg
Fluoride
 Role
in prevention of dental caries
– Helps tooth enamel resist acid
– Inhibits bacterial growth
Fluoride Sources and Needs
 Fluoridated
water
– ~0.2 mg/cup
– 1 ppm
 Tea,
seafood, seaweed
 Toothpaste
 Adequate Intake is 3.1 -3.8 mg/day
for adults
Fluoride Toxicity
 Mottling
of teeth in children
 Limit toothpaste to pea size for
children
– High amounts can weaken teeth
 Upper
Level is 1.3-2.2 mg/day for
children
 Upper Level is 10 g/day for older
children and adults
Chromium
 Enhances
insulin action
 Role in Type 2 diabetes?
 Low intake:
– Impaired glucose tolerance
– Elevated blood cholesterol and
triglycerides
Chromium Sources and Needs
Little information
 Egg yolk, bran, whole grain, cereal,
organ meat, meat, beer
 Plant sources dependent on soil content
 Adequate Intake is 25 - 35 µg/day for
adults
 Daily Value is set at 120 µg
 Average intake is ~30 µg/day

Chromium Toxicity
No toxicity from foods
 No Upper Level
 Exposure to chromium in environmental
waste sites
 Lung and liver damage

Manganese








Cofactor in carbohydrate metabolism
Component of superoxide dimutase
Role in bone formation
No deficiency symptoms observed in humans
Adequate Intake is 1.8-2.3 mg/day
Average intake meets AI
Daily Value is 2 mg
Toxicity in individuals working in manganese mines
– Psychiatric abnormalities, violence, impaired muscle
control

Upper Level is 11 mg/day
Molybdenum
Required by several enzymes
 Deficiency rare

– Increased heart and respiration rates
– Night blindness, mental confusion
– Edema, weakness, coma
RDA is 45 µg/day
 Daily Value is 75 µg
 Average intake is 75-110 µg/day
 Upper Level is 2 mg/day

Other Minerals
 Boron
 Nickel
 Silicon
 Vanadium
 Arsenic
Hypertension (HTN)
Systolic blood pressure/Diastolic blood
pressure
 Optimal BP: less than 120/80 mm Hg
 HTN

– Sustained systolic pressure >139mm Hg or
diastolic pressure >89 mm Hg
95% of all HTN have no clear cause
(primary or essential HTN)
 Secondary HTN

Why Control Blood Pressure?
Silent disease
 To prevent

– Cardiovascular disease
– Poor circulation
– Kidney disease
– Stroke, decline in brain functions

African Americans most at risk
Causes of HTN







Aging
Family history
Atherosclerosis
Obesity (increased fat mass and circulation)
Elevated insulin (insulin resistant adipose cells)
Inactivity
Excess alcohol (usually reversible)
Sodium and Blood Pressure
 Blood
 Fluid
pressure increases with intake
retention leads to increased
blood volume
Other Minerals and HTN
>1000 mg calcium per day lowers blood
pressure
 2-4 gm of potassium per day lowers blood
pressure
 Magnesium may lower blood pressure
 DASH diet
 Diet rich in fruits,vegetables (vitamin C)

Medications and HTN
 Diuretics
– Reduce blood volume
– Increase urine output
 Other
medications
– Slow heart rate
– Relax blood vessels
Osteoporosis
 Calcium
deficiency
 “A pediatric disease with geriatric
consequences”
 Leads to ~1.5 million fractures / year
Slender, inactive women who smoke are
most at risk
 “Less bones”

Osteoporosis
Bone Growth and Mass
Rapid and continual throughout
adolescence
 Peak bone mass
 Determined by gender, race, familial
pattern, other genetic factors
 Bone loss begins ~age 30
 Women experience increased bone loss
after menopause
 DEXA bone scan

Bone Mineral Density