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Chapter 11
Fat Soluble Vitamins:
ADEK
Chapter 11 - FSV
Characteristics of fat-soluble vitamins
• Do not dissolve in water, but dissolve in fat or
organic solvents.
• Dietary fat soluble vitamins need bile for
absorption.
• The fat-soluble vitamins include vitamins A, D,E
and K
• Found in the fats and oils of foods.
• Stored in the liver and fat tissue until needed
• not readily excreted from the body.
• Risk of toxicity.
Storage of vitamins in the body
• Vitamins A, D and E:
– These three fat-soluble vitamins can
accumulate in the liver and fat tissue of the
body and are not readily excreted. Long-term
intakes more than the RDA can be toxic,
particularly vitamins A and D.
• Vitamin K:
– The other fat-soluble vitamin, vitamin K, is
readily excreted from the body.
Absorption & transport
• The fat-soluble vitamins, like lipids are
absorbed with dietary fat.
– Bile aids in the absorption of fat-soluble
vitamins.
– The GI must function adequately for efficient
uptake of fat-soluble vitamins.
• Under normal conditions, healthy
individuals will absorb 40-90% of fatsoluble vitamins.
Absorption & Transport
Fat malabsorption interfere with the
absorption of FSV.
• Unabsorbed fat is excreted as feces.
• The following conditions adversely affect
the uptake of fat-soluble vitamins:
– Cystic fibrosis
– Crohn’s disease
– Celiac disease
– Certain medications
Vitamin A
Family of compounds called Retinoids:
• Retinol – supports reproductive functions
– Found in animal foods and nutrient supplements.
– Can converted to retinoic acid and retinal in the body.
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Retinal – Aid in vision
Retinoic acid – regulates growth
~90% of retinoids are absorbed
These are preformed Vitamin A – form that
the body readily uses. Found only in animal
sources
Provitamin A = carotenoids
• Found in plant sources
• Not biologically available until they are
changed into one of the retinoids in the
body
• There are over 600 different carotenoids
only 3 can be converted to vitamin A
– Beta carotene (most common form)
– Alpha carotene
– Beta- cryptoxanthin
• Accounts for 25 – 35 percent of dietary
vitamin A consumed in the US
Functions of Vit A
• Essential for healthy eyes
• Promotes cell differentiation
– Determines what cell becomes in your body
– Supports reproductive system, development of
limbs, heart eyes and ears
• Promotes bone and teeth growth
• Play a role in immunity and preventing
infections by creating white blood cells
• Carotenoids, which act as antioxidants,
decrease the damaging effects of free
radicals.
Sources of Vitamin A
Sources
• Preformed Vit A
– Organ meats (liver), milk, cereals, cheese and eggs
are the most popular sources of
• Provitamin A (carotenoids)
– Fruits: peaches, apricots, cantaloupes, mangoes,
papaya
– Vegetables: tomatoes, carrots, winter squash, sweet
potatoes, broccoli, romaine lettuce, collard greens
and spinach.
– Adding as little as 1 tablespoon of vegetable oil to
your diet can increase absorption of carotenoids by
as much as 25%
Vitamin A
RDA – can be measured in micrograms of retinoic
activity equivalents (RAE) or in international
units (IU). 1 RAE = 3.3 IU
• 900 microgram for men
• 700 microgram for women
• Upper limit 3,000 microgram/day
Deficiency
• Night blindness – difficulty seeing at dusk, can’t adjust
from day light to dark
• Vitamin A deficiency is the main cause of non-accidental
blindness (Xerophthalmia)
• Many die after blindness as a result of infection.
– The eye becomes prone to infections when the conjunctiva is
damaged.
– Infections can spread systemically throughout the body.
Toxicity
• Hypervitaminosis A - is a condition that results
from excessive intake of vitamin A from
supplements
• Cause defective physical development during
early development of the fetus resulting in birth
defects
– Even 3X RDA vitamin A is considered risky during
pregnancy.
• Accutane is associated with congenital
malformations result involving the head and brain.
• FDA has recommended that women of
childbearing years limit their vitamin A intake to
100% RDA
Toxicity
• High consumption of vitamin A has been
linked to osteoporosis and increased risk
of fractures
• Provitamin A carotenoids in foods are not
toxic
• Extra carotenoids are stored in the liver
and in the fat under the skin, causing
carotenodermia
Fig. 11-7, p. 375
Vitamin D/calceferol
• Also called the “sunshine vitamin”
because it is made with the help of
ultraviolet (UV) rays from sunlight
• Vitamin D enters your body in an
inactive form
• The kidneys convert dietary vitamin D
into the active form
• Precursor = body’s cholesterol
Vitamin D/ calceferol
• Functions of Vit D
– Helps bone health by regulating calcium and
phosphorus concentration in the blood
– When blood concentration of calcium is low,
vitamin D and parathyroid hormone signals
the kidney to decrease excretion of calcium
and phosphorous
• Sources of vit D
– Fortified milk, cereals, yogurt, fatty fish
Vitamin D
Adequate Intake:
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5 micrograms/day for 19-50 yr
10 micrograms/day for 51-70 yr
15 micrograms/day for >70 yr
Upper level: 50 micrograms/day
Vitamin D
Deficiency
• Rickets in children (soft bones)
– poor bone mineralization
– Bowed legs
– Unable to hold up their own weight when
standing up
– Recently researchers have found a rise in
rickets among children,
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linked to increase consumption of soft drinks
Limited outdoor activities
Fear of skin cancer
Air pollution reduces ultraviolet rays of the sun by
as much as 60%
Vitamin D
Osteomalacia - adult form of rickets
• Occurs in women with decreased calcium
and phosphorus intake
• Causes bone weakness and pain
• Can lead to osteoporosis
Vitamin D Toxicity
Hypervitaminosis D – associated with
over-consumption of supplements
• Increased calcium withdrawal in bones
and intestines
• Increased calcium and phosphorous
concentrations in the blood
(hypercalcemia)
• Increase calcium deposits in kidneys,
lungs, blood vessels and heart
Vitamin E
• Vitamin E is an effective antioxidant
– Prevent oxidation of lipids, vit A and LDL to
prevent build-up in the arteries
– Neutralize free radicals before they damage cell
membranes
– Prevents blood clotting in the blood by acting as
anticoagulant
• There are 8 different forms, only one is
active in the body (alpha- tocopherol)
• The synthetic is only half as active as the
natural
Vitamin E
Sources
• Polyunsaturated plant oils (vegetable oils)
• Nuts and seeds
• Leafy green vegetables
• Fortified cereals
RDA:
Adults need 15 milligrams/day
Upper limit is 1,000 milligrams
Vitamin E
Deficiency
• Erythrocyte hemolysis in premature infants
(red blood cell destruction causing
anemia)
Toxicity from synthetic form or fortified foods
• increase risk of hemorrhage
• A deficiency of vitamin K can increase the
anticoagulant effect
Vitamin K
There are two forms of vitamin K:
• Menaquinone – synthesized by the intestinal
tract
• Phylloquinone – found in green plants
Functions
• Essential for blood clotting
• Vitamin K plays a role synthesizing clotting
factors
• Without vit k a simple cut on the finger would
cause uncontrollable bleeding
• Synthesis of bone protein (osteocalcin) that
regulates blood calcium.
Vitamin K
• Inadequate amount of vitamin K may
contribute to osteoporosis, associated with
increased risk of hip fractures
Sources
• Intestinal bacteria can make vitamin K but
not enough to meet all of the body’s needs
• Leafy green vegetables
• Cabbage family vegetables
• Vegetable oils and margarine
Vitamin K
Deficiency
• Newborn infants receive a single dose of vitamin
K at birth because of a sterile intestinal tract to
prevent hemorrhagic disease
• Rare in healthy individuals
Toxicity
• No known adverse effect from consuming too
much vitamin K from food or supplement
• Interferes with anticlotting medication
(coumadin)
Recommendation for Vitamin K
Adequate Intake (based on amount that is
consumed on average)
Infants: 2 – 2.5 microgram
Children: 30 – 55 microgram
Men: 60 – 120 microgram
Women: 60 – 90 microgram
Homework/extra credit
5 points
Complete the vitamin/mineral
evaluation form posted on the
course website