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Fat Soluble Vitamins

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Fat Soluble Vitamins. Vitamins A, D, E, K. Require bile for absorption. Absorbed via lymph system ... Vitamin A - Fortified milk, cheese, cream, butter,eggs, liver ... – PowerPoint PPT presentation

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Title: Fat Soluble Vitamins


1
Fat Soluble Vitamins
  • Chapter 11


2
Fat Soluble Vitamins
  • Vitamins A, D, E, K
  • Require bile for absorption
  • Absorbed via lymph system
  • Transported by protein carriers
  • Excesses are stored in the body in the liver and
    adipose tissue
  • Toxicity may occur w/ oversupplementation

3
Vitamin A
  • General information
  • Retinoids retinol, retinal, retinoic acid
  • Precursor carotenoids (Beta carotene)

4
Vitamin A - RDA
  • Men
  • 900 µg RAE/day
  • Women
  • 700 µg RAE/day
  • Upper Level Adults 3000 µg/day

5
Vitamin A - Major Functions
  • Promotes vision
  • Protein synthesis cell differentiation
    maintaining skin tissue health
  • Supports reproduction growth
  • Beta-carotene is an antioxidant

6
Vitamin A - Deficiency
  • Vitamin A deficiency is the second cause of
    malnutrition on a global level
  • Night blindness one of first detectable signs
  • Blindness xerophthalmia, major cause of
    childhood blindness
  • Increased infection
  • Keratinization protein secretion

7
Figure 11-5Page 371
Vitamin ADeficiency SymptomNight Blindness
In dim light, you can make out the details in
this room. You are using your rods for vision.
A flash of bright light momentarily blinds you as
the pigment in the rods is bleached.
With inadequate vitamin A, you do not recover but
remain blinded for many seconds.
You quickly recover and can see the details again
in a few seconds.
8
Vitamin A - Toxicity
  • Oversupplementation is highly toxic
  • Body can store 1 year supply
  • Children especially susceptible
  • Symptoms bone abnormalities, liver
    abnormalities, blurred vision, headaches
  • Birth defects
  • High doses do not cure acne

9
Major Food Sources
  • Vitamin A - Fortified milk, cheese, cream,
    butter,eggs, liver
  • Beta-carotene Dark leafy greens, broccoli, deep
    orange fruits and vegetables

10
In-text Figure Page 375
The carotenoids in foods bring colors to meals
the retinoids in our eyes allow us to see them.
11
Figure 11-8Page 374
Vitamin A in Selected Foods
Micrograms RAE
Food Serving size
(kcalories)
RDA for men
RDA for women
VITAMIN A Dark green and deep orange vegetables
(green) and fruits (purple) and fortified foods
such as milk contribute large quantities of
vitamin A. Some foods are rich enough in vitamin
A to provide the RDA and more in a single serving.
12
Vitamin D
  • General information
  • Sunshine vitamin- produced by the liver when
    sunlight hits the skin
  • RDA 1997 AI
  • Adults 5µg/day (19-50 years) 10 µg/day (51-70
    yrs) 15 µg/day (70 yrs)
  • Upper Level 50 µg/day

13
Figure 11-9Page 376
Vitamin D Synthesis and Activation
In the skin
7-dehydrocholesterol (a precursor made in
the liver from cholesterol)
Ultraviolet light from the sun
Previtamin D 3
Foods
Vitamin D 3 (an inactive form)
In the liver
Hydroxylation
25-hydroxy vitamin D 3
In the kidneys
Hydroxylation
1,25-hydroxy vitamin D 3 (active form)
14
Vitamin D - Major Functions
  • Bone growth
  • Raises blood calcium and phosphorus levels by
  • Increasing GI absorption of calcium, phosphorus
  • Increasing kidney retention
  • Withdrawing calcium from bones

15
Vitamin D - Deficiency
  • Similar to calcium deficiency
  • Bone softening
  • Rickets -children
  • Osteomalacia - adults

16
Figure 11-10Page 377
Vitamin DDeficiency SymptomsBowed Legs
Bowed legs. In rickets, the poorly formed long
bones of the legs bend outward as weight-bearing
activities such as walking begin.
17
Vitamin D - Toxicity
  • Increased calcium absorption-high blood
    calcium-kidney stones/deposits in blood vessels
    (fatal)
  • Growth retardation

18
In-text Figure Page 378
The sunshine vitamin vitamin D.
19
Vitamin D-Food Sources
  • Fortified milk, margarine, butter, eggs, liver,
    fatty fish (herring, salmon, sardines)
  • Sunlight synthesis no risk of toxicity

20
Figure 11-11Page 378
Vitamin D Synthesis and Latitude
21
Vitamin E
  • General information
  • Alpha- tocopherol acts as an anti-oxidant
  • RDA - 2000
  • Adults 15 mg/day
  • Upper level 1000 mg/day

22
Vitamin E - Major Functions
  • Major Functions
  • Antioxidant
  • Free-radical scavenger/protects cell membrane,
    may reduce risk of heart disease by protecting
    LDL against oxidation

23
Figure 11-12Page 380
Free-Radical Formation and Antioxidant Protection
Free-radical formation and damage
1
2
3
O2 (oxygen)
Occasionally, oxygen gains an extra electron from
the electron transport chain, thereby generating
a free radical.
1
To regain its stability, the free radical
attacks a nearby molecule (such as a lipid or
protein) and steals an electron.
2
Left with an unpaired electron, this
molecule becomes a free radical itself and
attacks another nearby molecule. The chain
reaction continues, causing widespread damage.
3
Antioxidant protection
Active vitamin E
2
1
3
The destructive chain reaction is stopped,
but vitamin E is no longer active.
Antioxidants, such as vitamin E, neutralize
free radicals by donating one of their own
electrons.
Like vitamin E, vitamin C acts as an antioxidant
it also restores vitamin E to its active form. An
abundance of dietary antioxidants
minimizes free-radical damage.
1
2
3
24
Vitamin E - Deficiency
  • Rare
  • Erythrocyte hemolysis
  • Nerve destruction

25
Vitamin E - Toxicity
  • Toxicity is rare
  • Extremely high doses may interfere with
    blood-clotting of Vitamin K
  • Upper limit 1000 mg/day

26
In-text Figure Page 381
Fat-soluble vitamin E is found predominantly in
vegetable oils, seeds, and nuts.
27
Vitamin E - Food Sources
  • Food Sources
  • Polyunsaturated vegetable oils, green leafies,
    wheat germ,whole-grains, eggs, liver, nuts,
    seeds
  • Easily destroyed by heat, oxygen

28
Vitamin K
  • General information
  • Synthesized by GI bacteria
  • RDA 2001 AI
  • Men
  • 120 mg/day
  • Women
  • 90 mg/day

29
Vitamin K, Continued
  • Major Functions
  • Blood clotting
  • Food Sources
  • liver, green leafies, cabbage-type vegetables,
    milk

30
In-text Figure Page 384
Notable food sources of vitamin K include
milk, eggs, brussels sprouts, collards, liver,
cabbage, spinach, and broccoli.
31
Vitamin K Deficiency
  • Hemorrhaging occurs with deficiency
  • Newborns Sterile GI tract single dose of
    Vitamin K given at birth
  • Antibiotic therapy kill vitamin K-producing
    bacteria in gut

32
Vitamin K - Toxicity
  • Uncommon
  • High doses toxic to infants, pregnant women
  • Symptoms red blood cell hemolysis, jaundice,
    brain damage
  • Interference with anticlotting medications

33
Figure 11-1Page 368
Forms of Vitamin A
Retinol, the alcohol form
Retinoic acid, the acid form
Retinal, the aldehyde form
Cleavage at this point can yield two molecules of
vitamin A
Beta-carotene, a precursor
Sometimes cleavage occurs at other points as
well, so that one molecule of beta-carotene may
yield only one molecule of vitamin A.
Furthermore, not all beta-carotene is
converted to vitamin A, and absorption of
beta-carotene is not as efficient as that of
vitamin A. For these reasons, 12 µg of
beta-carotene are equivalent to 1 µg of vitamin
A. Conversion of other carotenoids to vitamin A
is even less efficient.
34
Figure 11-2Page 368
Conversion of Vitamin A Compounds
Retinyl esters (in animal foods)
Betacarotene (in plant foods)
IN FOODS
Retinoic acid (regulates growth)
Retinal (participates in vision)
Retinol (supports reproduction)
IN THE BODY
Notice that the conversion from retinol to
retinal is reversible, whereas the pathway from
retinal to retinoic acid is not.
35
Figure 11-3Page 369
Vitamin As Role in Vision
As light enters the eye, pigments within the
cells of the retina absorb the light.
The cells of the retina contain rhodopsin,
a molecule composed of opsin (a protein)
and cis-retinal (vitamin A).
Retina cells (rods and cones)
Light energy
cis-Retinal
trans-Retinal
As rhodopsin absorbs light, retinal changes
from cis to trans, which triggers a nerve impulse
that carries visual information to the brain.
Cornea
Eye
Nerve impulses to the brain
36
Figure 11-4Page 370
Mucous Membrane Integrity
Without vitamin A, the normal structure
and function of the cells in the mucous
membranes are impaired.
Vitamin A maintains healthy cells in the mucous
membranes.
Goblet cells
Mucus
37
Figure 11-6Page 372
Vitamin ADeficiency SymptomThe Rough Skin of
Keratinization
In vitamin A deficiency, the epithelial cells
secrete the protein keratin in a process known
as keratinization.
38
Animation
Watch how free radicals damage macromolecules
such as proteins, lipids, and DNA in a
self-perpetuating chain reaction. Observe how
antioxidants stabilize these highly reactive
compounds and interrupt this destructive cycle.
Click to view animation.
39
Figure 11-13Page 383
Blood-Clotting Process
Calcium and thromboplastin (a phospholipid) from
blood platelets
Fibrinogen (a soluble protein)
Vitamin K
Several precursors earlier in the series depend
on vitamin K
Prothrombin (an inactive protein)
Thrombin (an active enzyme)
Fibrin (a solid clot)
40
In-text Figure Page 389
41
Fig. H11-1 (1)Page 390
The Actions of Free Radicals and Antioxidants
(contd next slide)
42
Fig. H11-1 (2)Page 390
The Actions of Free Radicals and Antioxidants
(contd)
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