Download Chapter 11: Water and the Major Minerals

Perspectives in Nutrition
5th ed.
Gordon M.Wardlaw, PhD, RD, LD, CNSD
PowerPoint Presentation by
Dana Wu Wassmer, MS, RD
Chapter 11: Water and the Major
Minerals
Water
• Comprise 50-70% of the body
• Intracellular fluid
– Fluid within the cell
• Extracellular fluid
– Interstitial
– Intravascular
Fluid Balance
• Controlled by the electrolyte concentration
• “Where ions go, water is sure to follow”
• Osmosis
– Movement of water from a less concentrated to
a more concentrated solution
• Osmotic pressure
– Amount of force to prevent the dilution
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Movement of Water (Fig. 11-1)
Functions of Water
• Metabolic processes
• Solvent
• Body temperature regulation
– Water absorb any excess heat
– Body secretes fluids via perspiration
– Skin is cool as perspiration evaporates
• Removal of body waste
– Via urine
– Urea excretion
– Avoid concentrated urine
• Amniotic fluid, joint lubricants, saliva, bile
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Are You Drinking Enough?
• Recommend 1ml per 1kcal
• (Fig. 11-3)
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The Thirst Mechanism
• Not reliable
• (Fig. 11-4)
Water Safety
• Most drinking water are safe
• The Environmental Protection Agency
• Power to local and state authorities to
advise public
• Rural areas may need to have their water
tested
• Chlorine and ammonia are added to kill
most microbes—I.e. Cryptosporidium
• Chlorine can be evaporated via boiling or
standing
Toxicity of Water?
• Too much water without sufficient
electrolytes intake
• More water than the kidneys can handle
• Usually not a problem (people won’t drink
that much)
• Overwhelms the kidneys
• Headaches, blurred vision, cramps,
convulsions
Minerals
• Various functions
• Major minerals
– Require >100 mg /day
– Calcium, phosphorus
• Trace minerals
– Require < 100 mg/day
– Iron, zinc
Bioavailability of Minerals
• Not all ingested minerals can be
absorbed
• Presence of binders and dietary fiber
• Animal products are better absorbed
• Mineral/mineral competition
• Presence of vitamins
Functions of Minerals
• Metabolic roles
• Cofactors
• Body growth and development
Food Sources of Minerals
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Plants
Animals
(Animals eat plants)
Enrichment process adds iron
Risk for Mineral Deficiencies
• Calcium
• Iron
• Zinc
Toxicity of Minerals
• Especially with trace minerals
• Careful use of mineral supplements
• Avoid amounts above the Upper
Tolerable Intake Levels
Sodium
• Table salt (NaCl): 40% sodium, 60%
chloride
Absorption, and Excretion of
Sodium
• 95% of ingested sodium is absorbed
• Absorbed from the stomach, small
intestine and colon
• Excretion regulated by the kidneys
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Blood Pressure and Sodium
Regulator (Fig. 11-4)
Functions of Sodium
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Positive ion in extracellular fluid
Aldosterone regulates sodium balance
Key for retaining body water
Participates in nutrient absorption
Creates an electrical potential charge
Muscle contraction
Conduction of nerve impulses
Deficiency of Sodium
• Rare
• Persistent vomiting/ diarrhea
• Excessive perspiration (losing 2-3% of body
weight)
• Depletion of sodium in the body
• Muscle cramps, nausea, vomiting,
dizziness, shock, coma
• Normally kidney will respond by
conserving sodium
Food Sources of Sodium
• 1/3 - ½ of intake is added to food by
individual
• ½ - 2/3 is added by food manufacturers
• Lower salt products available
• Milk and Dairy products
• Breads, hot dogs, lunch meats, soups,
sauces, snack foods
• Sodium content listed on the labels
Sodium Needs
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Body only needs 100 mg/day
Minimum requirement is 500 mg/day
Daily Value is 2400 mg/day
Typical intake is 4000-7000 mg/day
“Salt Sensitive”
• 10%-15% of adults are
• High sodium intake leads to high blood
pressure
• Recommend 2-3 gm sodium per day
• Recommended for all individual
• You will adapt to a low-sodium diet
Potassium
• Positive ion in the intracelluar fluid
• Associated with lowering blood pressure
Absorption and Excretion of
Potassium
• 90% of potassium consumed is absorbed
• Regulated by aldosterone and the kidneys
Functions of Potassium
• Fluid balance, nerve-impulse transmission
• Muscle contraction
Foods Sources and Needs for
Potassium
• Found in fruits, vegetables, milk, grains,
meats, dried beans
• Minimum requirement is 2000 mg/day
• Daily Value is 3500 mg/day
• Typical intake is 2000-3000 mg/day
• Excess potassium is excreted by the kidneys
Potassium Deficiency
• Rare
• Use of diuretics
• Alcoholics, anorexia nervosa, bulimia
nervosa
• Loss of appetite, muscle cramps, confusion,
constipation, irregular heart beat
Chloride
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Negative ion for the extracellular fluid
Absorbed in the small intestine and colon
Excreted through the kidneys
Components of hydrochloric acid (HCl), immune
response, nerve function
Excess is excreted by the kidneys/perspiration
Minimum requirement is 700 mg/day
Much is obtained from salt consumption
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 the body is dependent on amount
absorbed
• Requires a slightly acidic environment
• Duodenum is the site of absorption
• Availability of vitamin D
• Normally absorb 25% of calcium in food
• Increase to ~60% during time of need (pregnancy,
infancy)
• Estrogen increases absorption
• Parathyroid hormone
Decrease Absorption of Calcium
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Rapid intestinal motility
High fiber intake
Excess phosphorus
Vitamin D deficiency
Presence of polyphenols (tannins) in tea
Menopause
Aging
Achlorhydria
How Blood Calcium is Regulated
• Blood level is maintained at the price of
bone calcium
• Parathyroid hormone - increases blood
calcium
– Retains calcium from excretion
– Increases calcium absorption via increase calcitriol
– Increases calcium release from bone
• Lower blood calcium
– Decreases parathyroid hormone and calcitriol
– Calcitonin
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Calcium Regulation (Fig. 9-9)
Functions of Calcium
• Blood clot
– Needed to convert prothrombin to thrombin
• Nerve impulses transmission
– Transmitted at the site of the target cell
• Muscle contraction
• Cell metabolism
– Binds with calmodulin
– Activates various enzymes
Bone Structure
Hydroxyapatite
(mature bone)
Calcium released
Supports and strengthens
Collagen protein matrix
parathyroid hormone +
1,25 (OH)2 vitamin D
Osteoblasts
Osteoclasts
Bone Mass
• During growth, osteoblast exceeds
osteoclast activity (make more than we
break down)
• More bone mass in areas under higher stress
• Peak bone mass reached between the age of
20-30
• Bone loss begins in mid-adulthood
• Significant loss at menopause
Building Higher Bone Mass
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Adequate diet
Healthy body weight
Normal menses
Weight-bearing physical activity
Moderate intakes of protein, phosphorus,
sodium, caffeine
• Non-smoker
• Lower the use of certain medications
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Structure of Bone (Fig. 11-8)
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Calcium and Blood Clotting
• Formation of fibrin
• (Fig. 9-13)
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Transmission of Nerve Impulses (Fig. 11-9)
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Muscle Contraction (Fig. 3-4)
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Calmodulin System (Fig. 11-10)
Other Roles of Calcium
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May lowers blood pressure
May reduce colon cancer
May reduce PMS symptoms
May lower blood cholesterol
May reduce kidney stones
Osteoporosis
• Calcium deficiency
• “A pediatric disease with geriatric
consequences”
• Leads to ~1.5 million fractures / year
• Factors to increase bone mass
Food Sources of Calcium
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Dairy products
Kale, collard, mustard greens
Calcium fortified foods
Tofu (if made with calcium carbonate)
Canned fish
Calcium Supplement
• Recommended for people who cannot
incorporate Ca into their diets
• Not recommended with high iron meal
• Calcium carbonate (40% calcium)
– For those with ample of stomach acid
– Found in antacids
• Calcium citrate (21% calcium)
– Enhance absorption due to acidity content
– Recommended for elderly
Risk With Calcium Supplements
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Lead contamination
No FDA regulation
Oyster shell
Bonemeal
Look for United States Pharmacopoeia
seal of approval
Calcium Needs
• Daily Value is 1000 mg/day
• Adequate Intake (based on 40% absorption)
is 1000 -1200 mg/day for adults
• Adequate Intake is 1300 mg/day for
adolescents (9-18 yrs. old)
• Average intake range from 600-800 mg/day
for women and 800-1000 mg/day for men
Can You Get Too Much Calcium?
• Small intestine prevents excess from being
absorbed
• Upper Level set at 2500 mg/day
• Kidney stones, calcium in the urine
• Hypercalcemia
• Calcification of tissue
• Less efficient absorption
Phosphorus
• Body absorption is based on body’s need
(70%-90%)
• Absorption enhanced by calcitriol
• Passive absorption based on the phosphorus
concentration in the lumen
• Excess excreted by the kidney
• Component of ATP, cell membrane, and
bone
• May be needed in elderly to preserve bone
Functions of Phosphorus
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80% found in bones and teeth
Found in every cell
ATP
DNA, RNA
Phospholipids
Acid-base balance
Deficiency of Phosphorus
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Contribute to bone loss
Decrease growth, tooth development
Rickets
Anorexia, weight loss
weakness, irritability, bone pain
Food Sources of Phosphorus
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Various foods
Dairy, bakery products, and meats
Some from food additives
Most difficult to limit intake of
RDA is 700 mg/day for adults
Daily Value is 1000 mg
Current intake exceeds RDA
Deficiency highly unlikely
Who is at Risk For Deficiency?
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Pre-mature babies
Alcoholics
Elderly with poor diets
Long-standing diarrhea
Use of aluminum-containing antacids (binds
to phosphorus)
Toxicity of Phosphorus
• Problem for individuals with inefficient
kidney function
• Phosphate ions bind calcium
• Calcium-phosphorus precipitates in body
tissues
• Upper Level is 3-4 g/day
• May compound bone loss if calcium intake
is low
Magnesium
• Primarily in green leafy plants
• Absorption based on body’s needs (40%60%)
• Absorption enhanced by vitamin D
• Kidneys regulate blood concentration of
magnesium
• Alcohol increases loss in the urine
• Much stored in the body
Functions of Magnesium
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An enzyme activator
Activates ATP
Contributes to DNA and RNA synthesis
Potassium and calcium metabolism
Proper nerve and cardiac functions
Insulin release from the pancreas
May dilate arteries
May prevent heart rhythm abnormalities
Deficiency of Magnesium
• Develops slowly
• Rapid heartbeat
• Weakness, muscle spasms, disorientation,
nausea, vomiting, seizures
• May increase the risk of osteoporosis
Food Sources of Magnesium
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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
Too Much or Too Little
Magnesium
• Magnesium loss
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Thiazide diuretic use
Heavy perspiration
Long-standing diarrhea or vomiting
Alcoholism
Disorientation, weakness, muscle pain, poor heart
function
• Toxicity is uncommon
– Associated with kidney disorder
– Weakness, nausea, malaise
Sulfur
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Nonionic and ionic forms
Part of an organic compound
Disulfide bridges
Acid-base balance
Drug detoxifying pathways
Part of a natural diet, primarily from protein
Used to preserve foods