Chapter 9: Water and
the Major Minerals
Water: Essential Nutrient

Death occurs
– Without food
– Without vitamins, minerals
– Without water
Water




Comprises 50-70% of the body
Muscle contains 73% water (fat
contains ~20%)
Intracellular fluid
– Fluid within the cell (2/3 of total)
Extracellular fluid
– Outside the cells (1/3 of total)
Water Content Varies By
Tissue



Lean muscle
Fat
Bones
Water Content Varies: By
Age



Newborn
Adult
Elderly
Water Content Varies
Daily




Salt intake
Hormonal
2 cups fluid = 1
pound
Kidneys excrete
excess
Functions of Water


Almost universal solvent
Dissolves
– Nutrients
– Wastes
– Urea
– Carbon dioxide
Functions of Water

Removal of body waste
–
–
–
–
–
Via urine
Excrete 1-2 quarts/day
Urea excretion
Sodium excretion
Avoid concentrated urine


21/2 cups --- dark yellow
Can promote kidney stones
Functions of Water

Body temperature regulation
– Metabolism generates heat
– Buildup is dangerous
– Water absorbs any excess heat
– Body secretes fluid via perspiration
– Skin is cool as perspiration evaporates
Functions of Water

Lubricant
– Joints
– Synovial fluid

Shock absorber
– Amniotic fluid
– Cerebrospinal fluid
Are You Drinking Enough?


Recommend 1ml per 1kcal
½ oz / pound body weight
Daily Water Losses




Urine – largest loss
Skin –ongoing evaporation
Lungs – vapor
Feces
Sources of Water



Fluids
– Water
– Other beverages
Food
– Fruits and
vegetables
– Meat
– All but dried foods
Metabolism
– Energy nutrients →
carbon dioxide,
The Thirst Mechanism





Not reliable
Concerns for infants, older adults,
athletes
Athletes need to monitor their fluid
status
Weigh themselves before and after
training
Goal is to consume 3 cups for every
pound lost
Ignoring Thirst



Shortage of water in the body
Increase fluid conservation
Antidiuretic hormone
– From the pituitary glad
– Forces the kidney to conserve water (reduce
urine flow)

Aldosterone
– Responds to the drop in blood pressure
– Signals the kidney to retain sodium (water)
Thirst





Signal is not triggered until person
loses 1%-2% of body weight in fluid
Lost of 4% causes muscle to lose
significant strength and endurance
Lost of 10%-12% causes heat
intolerance
Lost of 20% results in coma and death
Dark yellow urine is a sign of
inadequate fluids
Water Safety



Most municipal tap water is safe
The Environmental Protection Agency
and local municipalities look for
contaminants
Power to local and state authorities to
advise public
Water Safety




Chlorine and ammonia are added to
kill most microbes
Small cancer risk (2/1 million people)
Chlorine can be evaporated via boiling
or standing
Much higher risk in using untreated
water
Water Safety




Rural areas may need to have their water
tested due to well contamination due to
agricultural runoff
Estimated that 10 million Americans may
drink water that doesn’t meet EPA guidelines
Cryptosporidium, a parasite, sickened
400,000 people in Milwaukee; not killed by
chlorine
High risk people are advised to boil their
drinking water for one minute prior to use for
drinking (HIV-AIDS, chemotherapy patients)
Alternatives to
Chlorinated Tap Water








Boil
Store overnight
Filters
Activated carbon
Reverse osmosis
Distillation
UV sterilization
Ozone
Bottled Water


Expensive
Environmental impact
– Manufacture
– Transport
– Landfill
Bottled Water Sources

75% springs/wells
– Ozone

25% municipal tap water
– Carbon filtered
Bottled Water

Independent testing
–
–
–
–




1/3 was contaminated
Bacteria
Arsenic
Organic elements
Check label
Source
Treatment
State-interstate FDA regulated
Water Safety
Let cold water run for a minute
or two before drinking or using
in cooking; will reduce risk of
lead exposure
 Don’t use hot water for food
preparation

Water and Minerals

Related 3 ways
– Hard/soft water
– Fluid balance
– Acid base balance
Fluid Balance





Water shifts freely in and out of the cells
Controlled by the electrolyte concentration
“Where ions go, water is sure to follow”
Intracellular water volume depends on
intracellular potassium and phosphate
concentrations
Extracellular water volume depends on
extracellular sodium and potassium
concentrations
Na+, K+, Cl


Attract water
Dissolve in water
Electrical charge = electrolytes
Cell Membranes


Water permeable
Impermeable to minerals
Osmosis

The passage of a solvent such as
water through a semi-permeable
membrane from a less
concentrated compartment to a
more concentrated compartment
Osmosis

Water moves across membrane
– Low concentration to high
– Equalizes solute concentration

Minerals do not move
– Draw water across membrane
Acid-Base Balance


Blood pH 7.35-7.45
Death
– pH 8.0 alkalosis
– pH 6.8 acidosis

Buffers
– Protein
– Electrolytes
– Gather/release hydrogen ions
Minerals: Definition



Inorganic (contain no carbon)
Separate elements
Required in small amounts
Functions of Minerals






Cofactors
Bone and
connective tissue
Blood
Metabolism
Growth &
reproduction
Function/formation
nerves & muscles


Cell membrane
transport
Minerals function
together:
– Bone formation
– Electrolytes
– Blood
Minerals in the Body
Mineral Classification

Major minerals
– Require >100 mg /day (1/50 of a
teaspoon)
– Calcium, phosphorus

Trace minerals
– Require < 100 mg/day
– Iron, zinc
Bioavailability of Minerals



Not all ingested minerals can be
absorbed
Example: only 5% of the calcium in
spinach is absorbed because spinach
contains oxalic acid
About 25% of dietary iron is
absorbed (better absorbed from dairy
products)
Bioavailability of Minerals
Presence of binders and dietary
fiber
 Minerals in animal products are
better absorbed
 The more refined a food is, the
fewer minerals
 Only iron is added back to
enriched grain products

Fiber-Mineral
Interactions



Phytic acid (phytate) in grain fibers
can limit absorption of some minerals
by binding to them
Oxalic acid: substance in plants
(spinach) that binds minerals
High fiber diets can decrease the
absorption of iron, zinc, magnesium,
and other minerals
Bioavailability of Minerals


Mineral content of plant foods reflects
the soil in which is it grown
Mineral/mineral competition: too much
of one mineral can interfere with the
absorption of another
– Zinc interferes with copper absorption

Presence of vitamins: example,
vitamin C enhances absorption of iron
Toxicity of Minerals




Trace minerals are more toxic
Result of supplementation
Presence of contaminants in
supplements
Look for the United States
Pharmacopeia (USP)-approved brands
Iron Toxicity

Men in general and older women
should avoid multivitamin-mineral
supplements with iron because of
the risk of iron toxicity
Major Minerals
Sodium

Table salt (NaCl): 40% sodium,
60% chloride
Sodium







95% of ingested sodium is absorbed
Major 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
Deficiency of Sodium






Rare
Persistent vomiting/ diarrhea
Excessive perspiration (losing 2-3% of
body weight)
Depletion of sodium in the body
Muscle cramp, nausea, vomiting,
dizziness, shock, coma
Normally kidney will respond by
conserving sodium
Correcting Deficiency



Pedialyte for
children
Gatorade for adults
Salt foods
Dietary Sources of
Sodium




Average American eats 4-6 grams
sodium in foods and softened water
20% comes from salt added in cooking
or at the table
35-80% comes from processed foods
4-27% comes from water (issue at
500 mg level if water contains more
than 40 ppm (40 mg or 2 mEq/liter)
Sodium Content of Fresh
Foods
Plain pasta or
rice
Fruit (any)
<10 mg
Vegetables,
unsalted
Milk 1 cup
<75 mg
Meat, poultry,
fish unsalted
<90 mg
<10 mg
125 mg
Sodium Content of
Processed Foods
Potato chips 1 oz
180 mg
American cheese 1 sl 300 mg
Italian dressing 2 T
510 mg
Instant noodle soup
1170 mg
KFC chicken pot pie
2160 mg
Meat lover’s stuffed
pizza 2 slices
2850 mg
Sodium Needs




Body only needs 100-200 mg/day
Minimum requirement is 500 mg/day
Daily Value is 2400 mg/day
Typical intake is 4000-7000 mg/day
Sodium Adaptation
Today’s salt is tomorrow’s
urine
 People can adjust to the
lower salt taste

“Salt Sensitive”






10%-15% of adults are (particularly
African Americans)
High sodium intake leads to fluid
retention and high blood pressure
Recommend 2-3 gm sodium per day
Recommended for all individuals
High intake of sodium (>2000 mg)
increases calcium loss
Check your blood pressure regularly
Potassium




Positive ion in the intracellular fluid
Functions in fluid balance and nerve
impulse transmission
Associated with lowering blood pressure
90% of potassium consumed is absorbed
Food Sources and Need
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 Pyramid
High Potassium Foods






Baked potato: 844
mg
Milk: 377 mg
Raisins: 825 mg
Spinach: 419 mg
Sweet potato: 397
mg
Tomato: 254 mg







Tomato Juice: 400
mg
Beer: 128 mg
Coffee: 96 mg
Chocolate: 174 mg
Waffle: 146 mg
Eggnog: 420 mg
Vegetable soup:
337 mg
Potassium Deficiency




Rare
Use of diuretics
Alcoholic, anorexia nervosa, bulimia
nervosa
Loss of appetite, muscle cramps,
confusion, constipation, irregular heart
beat
Chloride



Negative ion for the extracellular
fluid
Components of hydrochloric acid
(HCl), immune response, nerve
function
Excess is excreted by the
kidneys/perspiration
Chloride



Minimum requirement is 700 mg/day
Much is obtained from salt
consumption (table salt is 60%
chloride)
High intake may cause high blood
pressure
Hypertension



Systolic blood pressure/diastolic blood
pressure
Optimal is less than 120 / 80 mm Hg
HTN is a sustained systolic pressure of
>140mm Hg or >90 mm Hg for
diastolic
Hypertension


95% of all HTN
have no clear cause
(primary or
essential HTN)
Secondary HTN:
related to other
conditions, like
kidney disease
Why Control Blood
Pressure?



Silent disease (may have no
symptoms)
Causes cardiovascular disease, kidney
disease, stroke, retinopathy, declining
brain function
African Americans most at risk
Causes of HTN






Aging
Atherosclerosis
Obesity (increased fat mass and
circulation)
Elevated insulin (insulin resistant
adipose cells)
Inactivity
Excess alcohol (usually reversible)
Sodium and Blood
Pressure





Unclear if it is sodium or chloride that
is responsible
Increases blood pressure with intake
Consume no more than 2400 mg/day
Increased blood pressure to excrete
sodium needed for sensitive people?
Fluid retention leads to increased
blood volume
Lifestyle Interventions in
Hypertension



Weight loss of as little as 10-15
pounds may normalize blood pressure
Regular physical activity
Avoid excess alcohol
Other Minerals and HTN




>1000 mg calcium a day lowers blood
pressure
2-4 gm of potassium a day lowers
blood pressure
Magnesium may lower blood pressure
DASH diet: low in sodium, high in
fruits, vegetables, whole grains,
includes lowfat dairy products
Medication and HTN

Diuretic
– Reduce blood volume
– Increase urine output

Slows heart rate
– relaxation of the blood vessels
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
Presence of dietary glucose and lactose
Increased need
Upper part of the small intestine is the site of
absorption
Availability of vitamin D
Absorption of Calcium




Normally absorb 25% of calcium in
food
Increase to ~60% during time of need
(pregnancy, infancy)
Estrogen increases absorption
Parathyroid hormone
Factors Decreasing
Calcium Absorption




Rapid intestinal motility
High fiber intake
Excess phosphorus
Fat malabsorption
Factors Decreasing
Calcium Absorption





Vitamin D deficiency
Polyphenols (tannins) in tea
Menopause
Aging
Achlorhydria
Blood Calcium is
Regulated
 Blood
level is maintained at the
price of bone calcium
 Blood level will be maintained
despite inadequate calcium
intake (by drawing from bones)
 Setting stage for future bone
fractures
Functions of Calcium
 Blood
clot
 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 the 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
 Reduce lead absorption

Osteoporosis
Calcium deficiency
 “A pediatric disease with geriatric
consequences”
 Leads to ~1.3 million fractures /
year



Slender, inactive women who smoke
are most at risk
“Less bones”
Osteoporosis
Bone Structure
Bone Strength


Dependent on bone mass and bone
mineral density
The more there is, the stronger the
bone
Bone Growth and Mass


Rapid and continual throughout
adolescence
Peak bone mass: highest attainable
density
– First 3 decades of life

Determined by gender, race, familial
pattern, other genetic factors
Bone Growth and Mass




Bone loss begin ~age 30
Women experience increased bone
loss after menopause
DEXA bone scan
No noticeable symptoms
Types of Osteoporosis
 Type
I (postmenopausal)
–Occurs after menopause
 Type II (senile)
–Occurs with age in men and
women
Risk Factors for
Osteoporosis








Age
Gender
Race
Inactivity
Low body weight
Diet low in calcium
Family history
Early menopause;
absence of menses







Low testosterone
levels in men
Anorexia, bulimia
Some medications
Cigarette smoking
Excessive alcohol
consumption
Caffeine, sodium
High protein diet
Diet and Lifestyle Factors







Adequate diet (Ca, vitamin D)
Healthy body weight
Correct hormonal irregularities
Normal menses
Weight-bearing and resistance physical
activity
Don’t smoke
Limit excessive intake of protein,
phosphorus, sodium, caffeine, wheat bran,
and alcohol
Prevention






Regular menstruation
Weight-bearing exercise (but does not
compensate for lack of menstruation)
Smoking lowers estrogen
concentration in the blood
Alcohol is toxic to bone cells
Estrogen replacement therapies
Accurate measurement of height
Medication

Estrogen
– Slows bone turnover

Fosamax (bisphosphonates)
– Slows bone breakdown

Evista (selective estrogen receptor
modulators)
– Slows bone turnover

Calcitonin
– Inhibits bone breakdown

Side effects
Diet and Lifestyle Factors






Adequate diet (Ca, vitamin D)
Healthy body weight
Normal menses
Weight-bearing physical activity
Don’t smoke
Limit excessive intake of protein,
phosphorus, sodium, caffeine, wheat
bran, and alcohol
Food Sources of Calcium
 Dairy
products
 Kale, collard, mustard greens
 Calcium fortified foods
 Tofu (if made with calcium
carbonate)
 Canned fish
Food Sources of Calcium

Dairy foods provide
75% of the calcium
in the American diet
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 stomach acid
– Found in antacids

Calcium citrate (21% calcium)
– Enhanced absorption due to acidity content
– Recommended for elderly
Risk With Calcium
Supplements





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 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
Phosphorus





Body absorption is based on body’s
need (70%-90%)
No disease associated with deficiency
May contribute to bone loss in elderly
women
Vitamin D enhances absorption
Component of ATP, cell membrane, and
bone
Food Sources of
Phosphorus








Widely available in foods
Dairy, bakery products, sodas, and
meats
Some from food additives
Most difficult to limit intake
RDA is 700 mg/day for adults
Daily Value is 1000 mg
Current intake exceeds RDA
Deficiency highly unlikely
Toxicity of Phosphorus




Problem for individuals with inefficient
kidney function
Phosphate ions bind calcium
Chronic imbalance may lead to bone
loss (Ca+/phos ratio)
Upper Level is 3-4 g/day
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 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
May prevent heart rhythm
abnormalities
Deficiency of Magnesium




Develops slowly
Irregular heartbeat
Decreased blood pressure
Weakness, muscle spasms,
disorientation, nausea, vomiting,
seizures
Food Sources of
Magnesium







Plant products: Whole grains, vegetables,
nuts, seeds
Hard tap water
Dairy, chocolate, meat
RDA for women is 320 mg/day
RDA for men is 400 mg/day
Daily Value is 400 mg
Average intake is lower than the RDA
Magnesium Pyramid
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 medication
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