Download Key Vitamins and Minerals lecture 5

Key Vitamins and Minerals
Osteoporosis, Hypertension
And Water
Vitamins…
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are essential, non-caloric nutrients needed in
tiny amounts from the diet that help drive cell
processes.
Two types: fat soluble and water soluble.
Fat soluble vitamins are A, D, E, and K.
Water soluble vitamins are the B vitamins and
vitamin C.
Fat soluble vitamins A, D, E. &
K….
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Are found in the fats and oils of foods.
Are stored in the liver and in the fatty tissues
of the body for long periods.
Deficiency of these vitamins is rare though
can occur with a fat-free diet over long
periods.
Toxicity is a greater risk if these vitamins are
taken as supplements daily.
Vitamin A And
Beta-Carotene
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Vitamin A

Chief functions in the body
Vision
 Maintenance of cornea, epithelial
cells, mucous membranes, skin
 Bone and tooth growth
 Reproduction
 Immunity

Vitamin A And
Beta-Carotene
Vitamin A in vision
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Food Sources of Vitamin A
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Preformed, active vitamin A found in animal
sources: liver, and fish oil (richest sources),
fortified milk and milk products.
Pre-cursor, Beta carotene found in yellow
coloured vegetables and fruit, e.g, yellow
squash, sweet potato, cantaloupe, apricots,
mango. Dark green vegetables, e.g., spinach
provides some beta carotene as well
Vitamin A deficiency
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Not common in western world but very
common in developing countries.
causes blindness, keratinization (hardening
and thickening of skin), stunted growth,
impaired immunity, poor appetite and death.
Diseases such as measles much more severe
with vitamin A deficiency.
Toxicity of vitamin A
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Not common unless large amounts of liver
eaten.
More common from supplements providing
several times the recommended level.
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Occurs because vitamin A is stored in the liver and
adipose tissue and accumulates.
Toxicity from beta-carotene does not occur
because conversion to retinol is inefficient.
Toxicity of vitamin A continued
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Body can produce 1 unit of retinol from about
6 of beta-carotene.
Excess beta-carotene turns people yellow, but
is reversible.
Symptoms of toxicity from vitamin A include:
abdominal pain, hair loss, joint pain, stunted
growth, bone and muscle soreness, cessation
of menstruation, nausea, diarrhea, rashes,
enlargement of spleen and damage to liver.
Vitamin D
1,25-dihydroxycholecalciferol
Precursor is the body’s own
cholesterol
raises blood calcium by acting on the
skeleton, kidneys and the digestive tract
to release calcium
functions as a hormone
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Role of vitamin D continued
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It has a role in the brain, pancreas,
skin, reproductive organs and some
cancer cells but these roles are not fully
understood.
It also stimulates cell maturation
including immune cells.
Vitamin D

Significant sources
Synthesized in the body with the
help of sunlight
 Fortified milk, margarine, butter,
cereals, and chocolate mixes
 Veal, beef, egg yolks, liver, fatty
fish (herring, salmon, sardines)
and their oils
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How is vitamin D made from
sunlight?
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Ultraviolet light shines on a cholesterol
compound in human skin, the compound is
transformed into a vitamin D precursor and is
absorbed directly into the blood.
Over 1 1/2 days, the kidneys and liver finish
converting the precursor to active vitamin D.
Kidney or liver disease may affect this
process.
Exposure to UV light
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Light-skinned people require 10-15 minutes
exposure to UV light to make vitamin D.
Dark-skinned people require up to 3 hours
exposure depending on the climate.
Clouds, smog, heavy clothing, window glass
affect exposure.
Elderly, institutionalized, night-shift workers
may develop deficiency, therefore A.I. values
higher with age.
Vitamin D
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Deficiency symptoms: rickets
in children
Inadequate calcification,
resulting in misshapen bones
(bowing of legs)
 Enlargement of ends of long
bones (knees, wrists)
 Deformities of ribs (bowed, with
beads or knobs)
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Vitamin D
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Deficiency symptoms: rickets
in children (continued)
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Delayed closing of fontanel,
resulting in rapid enlargement of
head
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Vitamin D
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Deficiency symptoms: rickets
in children (continued)
Lax muscles resulting in
protrusion of abdomen
 Muscle spasms
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Deficiency symptoms:
osteomalacia in adults
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Loss of calcium, resulting in soft,
flexible, brittle, and deformed
bones
Vitamin D
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Toxicity symptoms
Most toxic of all the vitamins
Elevated blood calcium
 Calcification of soft tissues
(blood vessels, kidneys, heart,
lungs, tissues around joints)
 Frequent urination
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Vitamin E
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Other name: alpha-tocopherol
Chief function in the body
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Antioxidant (stabilization of cell
membranes, regulation of oxidation
reactions, protection of
polyunsaturated fatty acids and
vitamin A)
Vitamin E
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Vitamin E

Significant sources
Polyunsaturated
plant oils
(margarine, salad
dressings,
shortenings)
 Leafy green
vegetables, wheat
germ, whole grains,
liver, egg yolks,
nuts, seeds

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Vitamin E
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Easily destroyed by heat and
oxygen
Deficiency symptoms
Red blood cell breakage
 Nerve damage
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Toxicity symptoms
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Augments the effects of anticlotting medication
Vitamin K
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Chief functions in the body
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Synthesis of blood-clotting
proteins and bone proteins that
regulate blood calcium
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Vitamin K
Sources:
Bacterial
synthesis in the
digestive tract
 Liver
 Leafy green
vegetables,
cabbage-type
vegetables
 Milk

Copyright 2005 Wadsworth Group, a division of Thomson Learning
Vitamin K
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Deficiency symptoms
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Hemorrhaging
Toxicity symptoms
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None known
Water Soluble vitamins
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B vitamins and Vitamin C are water-soluble.
Cooking and washing leaches them from
foods.
The body absorbs them easily and easily
excretes them in the urine.
Some water soluble vitamins can be stored in
the lean tissue for about 1 month.
Toxic levels are not reached through foods
but can be reached through intake of
supplements.
B vitamins act as co-enzymes &
are involved in energy
metabolism
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A Coenzyme is a small molecule that
combines with an enzyme to make it active.
B vitamins: thiamin, riboflavin, niacin,
pantothenic acid and biotin participate in the
release of energy from carbohydrate, protein
and fat. Vitamin B6 helps the body use amino
acids to make protein. Folate and B12 help
cells to multiply.
Folate
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Required to make all new cells. Helps to
synthesize the DNA needed for the new cells.
Deficiencies result from inadequate intake
and illness that impairs absorption, increases
excretion or increases the need for more
folate.
Folate deficiency occurs in significant
numbers in Canada and USA.
Folate
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Absorption
Activation
 Vitamin B12
Folate
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Neural tube defects
 Spina bifida
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Folate
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Heart disease
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Homocysteine
Cancer
Folate
Sources
Fortified grains
Leafy green
vegetables,legumes,
seeds, orange juice,
liver
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Folate:
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Deficiency symptoms
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Anemia (large-cell type)
Smooth, red tongue
Mental confusion, weakness, fatigue,
irritability, headache
Toxicity symptoms
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Masks vitamin B12-deficiency
symptoms
Vitamin B12 - cyanocolbalamin
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Helps folate make red blood cells.
Maintains the sheaths that surround
and protect nerve fibres and may also
influence cells that build bone tissue.
Reforms folate coenzyme
Helps to break down some fatty
acids and amino acids
Vitamin B12
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Absorption
 HCl
 Pepsin
 Intrinsic factor required for
activation
Vitamin B12
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Deficiency of folate or B12 produces
pernicious anemia
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Vitamin B12:
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Significant sources
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Animal products (meat, fish, poultry,
shellfish, milk, cheese, eggs)
Fortified cereals
Easily destroyed by microwave
cooking
Vitamin B12: In Summary
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Deficiency symptoms
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Anemia (large-cell type)
Fatigue, degeneration of peripheral
nerves progressing to paralysis
Toxicity symptoms: none reported
Vitamin C
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Chief functions in the body
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Collagen synthesis
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Strengthens blood vessel walls, forms
scar tissue, provides matrix for bone
growth
Antioxidant
Thyroxin synthesis
Amino acid metabolism
Strengthens resistance to infection
Helps in absorption of iron
Vitamin C
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Significant sources
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Citrus fruits
Cabbage-type vegetables, dark green
vegetables (such as bell peppers and
broccoli)
Cantaloupe, strawberries
Lettuce, tomatoes, potatoes
Papayas, mangoes
Easily destroyed by heat and
oxygen
Vitamin C
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Deficiency disease: scurvy
Deficiency symptoms
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Anemia (small-cell type)
Atherosclerotic plaques
Pinpoint hemorrhages, bone fragility, joint
pain
Poor wound healing, frequent infections,
bleeding gums, loosened teeth
Muscle degeneration and pain, hysteria,
depression, rough skin, blotchy bruises
Vitamin C
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Toxicity symptoms
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Nausea, abdominal cramps, diarrhea
Headache, fatigue, insomnia
Hot flashes, rashes
Interference with medical tests,
aggravation of gout symptoms,
urinary tract problems, kidney stones
Calcium
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Most abundant mineral in the body.
99% of body’s calcium is in the bones and
teeth
Integral part of bone structure: serves as a
calcium bank that can be released if calcium
levels drop in the blood.
Calcium in body fluids regulates transport of
ions across cell membranes and is particularly
important in nerve transmission.
Calcium continued
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Helps maintain normal blood pressure
Essential for muscle contraction and
therefore heartbeat
Allows secretion of hormones, digestive
enzymes and neurotransmitters
Plays important role in clotting of blood.
May play role in maintaining healthy
body weight.
Calcium balance is tightly
controlled
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Blood calcium is regulated by hormones
sensitive to blood calcium and not by
dietary intake.
Inadequate intake of calcium in early
life results in poor bone mass and can
lead to osteoporosis.
Calcium recommendations
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Adolescents: 1300 mg/day
Adults 19 -50, 1000 mg/day
Adults over 51, 1200 mg/day
UL: 2500 mg/day
Food sources: milk and dairy products best
source, small bones of fish like salmon and
sardines, dark green vegetables like broccoli,
kale, and spinach; legumes
Calcium in Other Foods
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Some brands of tofu, corn tortillas,
almonds, sesame seeds.
Mustard and turnip greens, bok choy,
kale, parsley, watercress.
Calcium fortified orange juice.
Calcium Absorption
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Many factors affect Ca absorption.
Factors that enhance Ca absorption:
• Stomach acid
• Vitamin D
• Lactose
• Growth hormones.
Calcium Absorption
Factors that inhibit Ca absorption:
• Lack of stomach acid.
• Vitamin D deficiency.
• High phosphorus intake.
• High- fiber intake.
• Phytates (seeds, nuts, grains)
• Oxalates (beet greens, rhubarb, spinach)
Osteoporosis
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Osteoporosis is thinning of bone mass in
older persons leading to porous, fragile bones
that break easily.
Peak bone mass is achieved by about age
20 for females and 30 for males. After age
40, bone loss occurs regardless of calcium
intake though can be slowed by high calcium
intake. Women lose bone faster with loss of
estrogen at menopause.
Healthy vs. Osteoporotic Trabecular Bones
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Osteoporosis And Calcium
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Preventing
Osteoporosis
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Calcium
Physical
activity and
body weight
Smoking
and alcohol
Drug
therapies
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Calcium:
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Supplements
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Multivitamin-mineral pills contain little
or no Calcium.
Typically sold as compounds of Ca
carbonate, citrate, gluconate, lactate,
malate, or phosphate.
Some are made from bone meal, oyster
shell, or limestone (dolomite).
Many “natural” products contain lead.
Sodium
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The principle cation in the extracellular fluids
of the body.
Helps to maintain acid-base balance
Is essential to muscle contraction and nerve
transmission
40% of body’s sodium thought to be stored
on surface of bone crystals where body can
easily draw it into blood.
Sodium continued
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Deficiency would be harmful but few diets lack
sodium.
Kidneys can conserve if necessary.
Excess excreted through urine. Generally amount
excreted represents intake for the day.
Sodium/water ratio delicately balanced by kidneys.
Too much sodium, thirst mechanism kicks in, more
water dilutes sodium, excesses of both excreted.
Sodium continued
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Deficiency can occur in overzealous treatment with
low-sodium diets for hypertension, kidney disease or
heart disease. Vomiting, diarrhea, and excessive
sweating can also deplete sodium.
No DRI recommendations set because no human diet
lacks sodium. Nutrition Recommendations in Canada
suggest reducing sodium intake. Generally for good
health maximum intake should be about 2500mg
sodium chloride (salt)/day. Sodium is 40% of sodium
chloride.
Sodium and hypertension
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Controversy still exists.
In salt-sensitive people, high sodium
intakes raise blood pressure. Not the
case with non salt-sensitive people.
Overweight people also appear to be
particularly sensitive to the effect of salt
on blood pressure.
Sodium
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Sodium: In Summary
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Deficiency symptoms
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Toxicity symptoms
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Muscle cramps, mental apathy, loss of
appetite
Edema, acute hypertension
Significant source
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Table salt, soy sauce
Moderate amounts in meats, milks,
breads, and vegetables
Large amounts in processed foods
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Potassium
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Principal cation within the body’s cell.
Chief functions in the body
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Maintains normal fluid and electrolyte
balance
Facilitates many reactions
Supports cell integrity
Assists in nerve impulse transmission and
muscle contractions
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Potassium: In Summary
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Deficiency symptoms
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Muscular weakness
Paralysis
Confusion
Toxicity symptoms
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Muscular weakness
Vomiting
If given into a vein, can stop the
heart
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Potassium: In Summary

Significant
sources
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All whole foods
Meats, milks,
fruits, vegetables,
grains, legumes
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Magnesium
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Chief functions in the body
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Bone mineralization.
Building of protein.
Enzyme action.
Normal muscle contraction.
Nerve impulse transmission.
Maintenance of teeth.
Immune system
Magnesium
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Deficiency symptoms
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Weakness
Confusion
If extreme, convulsions, bizarre
muscle movements (especially of eye
and face muscles), hallucinations,
and difficulty in swallowing
In children, growth failure
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Magnesium
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Significant sources
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Nuts, legumes
Whole grains
Dark green vegetables
Seafood
Chocolate, cocoa
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Magnesium toxicity
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UL – 350mg/day from supplements/medications only
(does not include food and water sources)
Toxicity occurs in older people abusing magnesium
based laxatives, antacids and other medications.
Symptoms severe: diarrhea, acid-base imbalance,
kidney impairment, confusion. poor coordination,
coma, death.
Iron
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Present in every living cell. It is an essential
nutrient.
Principal component of two proteins –
hemoglobin in red blood cells and myoglobin
in muscle cells.
Hemoglobin in blood carries oxygen from the
lungs to tissues throughout the body and
myoglobin stores oxygen for muscles. Iron
allows oxygen to be held and released from
these proteins.
Iron continued
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The liver makes iron sent from the bone
marrow, into new red blood cells an releases
them into the blood.
Red blood cells live for about 3 months.
When they die, the spleen and liver breaks
them down, salvages the iron and sends it to
the bone marrow for reuse.
Small losses of iron occurs from skin, nails
and hair clippings. Major losses occur through
bleeding.
Iron recommendations
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Food sources: red meat, poultry,
seafood provide heme iron, best
absorbed type.
Dark green leafy vegetables, legumes,
provide non-heme iron, less well
absorbed.
Iron deficiency – depleted
stores
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May arise from inadequate intake,
malnutrition, blood loss, parasitic infestation
in digestive tract which results in blood loss.
Severe depleted stores results in anemia.
Anemia results in inability to make enough
hemoglobin to fill its new red blood cells.
Results in apathy, tiredness, reduced capacity
to work, sensitivity to cold.
Iron overload - Hemochromatosis
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Iron is toxic in large quantities – difficult for
body to excrete.
Hereditary defect which affect more men than
women, causes the intestine to over-absorb
iron. Tissue damage occurs especially in the
liver, infections can increase because bacteria
thrive in iron-rich blood.
Condition worse in alcohol abusers because
alcohol damages intestine impairing its
defense against absorbing too much iron
Bioavailability of iron
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Meat, poultry and fish contain an MPF factor
which enhances absorption of heme iron and
can triple absorption of non-heme iron from
foods in the same meal.
Vitamin C greatly enhances iron absorption
Phytates and tannins diminish iron absorption
Iron Supplements
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Less well absorbed than from food.
Ferrous sulfate is better than other iron
supplements.
Absorption improves when taken between
meals or a bedtime on an empty stomach or
with liquids other than milk, tea or coffee
which inhibit absorption.
No benefit to taking supplements with vitamin
C. Vitamin C does not enhance absorption
from supplements as it does from foods.
Zinc
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Required as a Co-factor by more than 100
enzymes.
All cells contain Zn, but the highest
concentrations are in muscle and bone.
Interacts with platelets in blood clotting.
Essential to normal taste perception, wound
healing and making of sperm and fetal
development.
Help metabolize protein, fat and CHO.
Participates in synthesis, storage and release
of hormone insulin in the pancreas.
Zinc
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Need to produce the active form of vitamin A
(retinal).
Stabilizes cell membranes, helping to
strengthen their defense against free-radical
attacks.
Assists in immune function and in growth and
development.
Affects thyroid hromone function.
Influences behavior and learning
performance.
Zinc
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Significant
sources
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Proteincontaining
foods
Red meats,
shellfish
Whole grains
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Zinc Absorption
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Absorption varies from 15-40% depending on
a person’s Zn status.
Dietary factors influence Zn absorption. Fibre
and phytates bind Zn which limits its
bioavailability.
Once absorbed into an intestinal cell, it may
become involved in the metabolic functions of
the cell itself or may be retained within the
cell by metallothionein (a special binding
protein similar to the Fe storage protein,
mucosal ferritin)
Zinc
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Deficiency
symptoms

Growth
retardation,
delayed sexual
maturation,
impaired immune
function, hair loss,
eye and skin
lesions, loss of
appetite
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Zinc deficiency
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Impairs immune function and increases susceptibility
to infections.
Stunts growth, alters digestion and absorption
causing diarrhea and increases malnutrition.
Zn deficiency directly impairs vitamin A metabolism
so vitamin A deficiency symptoms often appear. .
Impairs the immune response, making infections
likely – infections of the GI tract.
Disturbs thyroid function and the metabolic rate.
Alters taste, causes loss of appetite and slows wound
healing.
Zinc toxicity
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Toxic in large quantities can cause
serious illness and death.
High doses of zinc block copper and
iron absorption.
Zinc from food never a problem but
from supplements and medications e.g.,
throat lozenges.
Zinc: food sources

Food sources: shellfish, poultry are best
sources, legumes and enriched cereals.
Water
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Water is the most essential nutrient in
the body. We can live for several days
without food, but not without water.
Carries nutrients throughout the body.
Cleanses the blood of wastes.
Serves as a solvent for minerals,
vitamins, amino acids, glucose and
other small molecules.
Water continued
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Actively participates in many chemical
reactions.
Acts as a lubricant around joints.
Serves as a shock absorber inside the
eyes, spinal cord, joints, and amniotic
sac surrounding a fetus in the womb.
Aids in maintaining the body’s
temperature.
The body’s water balance
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Water makes up about 60% of the body’s
weight.
The body must excrete a pint (500 mls) of
water a day to cleanse its fluids, therefore a
person must drink at least that much a day to
avoid life threatening losses and maintain
water balance.
The total amount of fluid is kept constant by
delicate balancing mechanisms.
Water balance continued
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Water balance maintains blood volume, which
in turn influences blood pressure.
If the body loses too much water, blood
volume and blood pressure fall.
When this occurs, the hypothalamus signals
the pituitary gland to release the antidiuretic
hormone (ADH).
ADH stimulates the kidneys to reabsorb water
rather than excrete it.
Water balance continued
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Cells in the kidney respond to low blood
pressure by releasing an enzyme called renin.
Renin causes the kidneys to reabsorb sodium.
Sodium reabsorption is always accompanied
by water retention which helps restore blood
volume and blood pressure.
Water balance continued
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Renin also activates the blood protein
angiotensinogen to angiotensin.
Angiotensin is a powerful vasocontrictor. It
narrows the diameter of the blood vessels
thereby increasing blood pressure.
Angiotensin also helps with the release of the
hormone aldosterone which causes the
kidney to retain more sodium and therefore
more water.
The net effect is that when more water is
needed less is excreted.
Thirst mechanism
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Thirst and satiety govern water intake. When
the blood is too concentrated, water is
attracted by molecules in the blood out of the
salivary glands.
The mouth becomes dry and you drink.
The hypothalamus and the kidneys also
regulate water by monitoring blood
concentrations as described on the previous
slide.
Quenching thirst
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Thirst lags behind a lack of water.
Thirst is the first sign of dehydration
indicating that the body has lost up to 2 cups
(500 mls) of its total fluid.
Children and the elderly have delayed thirst
mechanisms.
A loss of just 5% of body fluid initiates
symptoms of headache, fatigue, confusion or
forgetfulness, and elevated heart rate.
Severe dehydration (heat stroke)

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
As dehydration increases, sweating stops.
Water is redirected into the blood vessels to
maintain blood pressure.
Sweating is the cooling mechanism of the
body. Without sweat, the body overheats.
This can lead to rapid shallow breathing,
weak irregular pulse, thickening of the blood,
shock, seizures, coma and death.
How much water do we need?
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Water needs depend on the foods eaten
(because foods contain water), the
environmental temperature and humidity, and
a person’s activity level.
Adults need between 1 and 11/2 mls of
water from al sources for every calorie spent
in the day. E.g, for 2000 calories, need about
2 to 3 L (8 to 12 cups of water per day.
Sweating increases fluid needs.
Food sources of water
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Nearly all foods contain water. (see table
page 268 in text)
Fruits and vegetables contain large amounts
of water – up to 95% of their volume.
Beverages like regular soft drink, juice and
milk contain 80-89% water.
Meats & cheeses up to 50%.
Beverages containing caffeine and alcohol
have a negative (diuretic) effect on water
balance.