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OUTLINE
Topic Subtopics
I Introduction
Characteristics
Chemistry
Metabolism
Functions
Sources
IIVitamin A
Deficiency
Causes
Manifestation
Management
Daily Requirements
III Vitamin A Toxicity
Causes
Manifestation
Management
IV Case Report
Case Presentation
Analysis of ManifestationManagement
Vitamins
Nutrition
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OBJECTIVES
1. To discuss the characteristics and
chemistry of Vitamin A2. To discuss Vitamin A metabolism(absorption, storage, transport, excretion)
3. To explain its different functions in the
body
4. To site food sources of Vitamin A
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VITAMIN A
aka ANTI-INFECTIVE VITAMIN
Hydrophobic
Fat-soluble vitamin
Requires SPECIFIC BINDING PROTEINS for transport
Stored in the LIVERand adipose tissues
LESSprone to DEFICIENCY
MOREprone to TOXICITY
CHARACTERISTICS
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VITAMIN A
CHEMISTRY
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VITAMIN A
FORMS
RETINOIDS CAROTENESActiveForm Inactive, Precursor or Provitamin
A
Found in ANIMAL
SOURCES
Found in PLANTSOURCES
Forms of Retinoids:
1. Retinolalcohol form
2. Retinal
aldehyde form3. Retinoic Acidacid
form
4. 3-Dehydroretinol
Important Types in food:
1. Alpha-carotene
2. Beta-carotene
most commonform
3. Gamma-carotene
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FORMS
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Absorption, Storage and
Transport of Vitamin A
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Excretion of Vitamin A
60%is excreted in the URINE
40%in FECES
Thus, the KIDNEYSare the main paths of RBP and
retinol excretion from the body (Stipanuk, 2006; Gropper,Smith, & Groff, 2008; Helwig, 2013)
METABOLISM
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Functions of Vitamin A
1. Vision
FUNCTIONS
2. Gene transcription
3. Skin and cellular health,
Immune function4. Embryonic development
and reproduction
5.Hematopoiesis
6. Bone metabolism
7. Antioxidant activity
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VISION
FUNCTIONS
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GENE TRANSCRIPTION
ALL-TRANS RETINOIC ACIDor 9 CIS RETINOIC ACID
Binds to specific cellularretinoic acid binding
protein
(receptor)
RETINOIC ACID-RECEPTOR COMPLEX
binds to DNA
Regulates the expression ofgenes required for growth and
differentiation
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SKIN & CELLULAR HEALTH
RETINOLinvolved in
the maintenance ofepithelial integrityand glycoprotein
synthesis
RETINOLprevents theexcess keratin
synthesis
RETINOL
PHOPSPHATEformed from retinol
is required forglycoprotein
synthesis
GLYCOPROTEINS areimportant component ofthe MUCUS secreted by
epithelial cells
RETINOL PHOSPHATE forms GLYCOSYLRETINYL PO4 that acts as a donor of
CHO (mannose, galactose, etc.) forGLYCOPROTEIN &
MUCOPOLYSACCHARIDE synthesis
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EMBRYONIC DEVELOPMENT &
REPRODUCTION
RETINOLbinds to specific
intracellular receptor(Cellular RetinolBinding Protein)
RETINOL-RECEPTORCOMPLEX
binds to DNA
Regulates the expression ofgenes required forreproductive function.
[Mechanism of action is similarto steroid hormone action]
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HEMATOPOIESIS
- Process of formation of blood cells inthe living body
VITAMIN A ADEQUACY- Improves hemoglobin concentration
VITAMIN A DEFICIENCY
- Impairs Iron mobilization from stores
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BONE METABOLISM
1st
VITAMIN A (RETINOIC ACID) converts immaturecells to OSTEOBLASTS
2nd
OSTEOBLASTS are responsible for the increase inthe number of Bone cells and OSTEOCLASTS
3rd
OSTEOCLASTS are necessary for the breakdown ofbone cells as bone is remodeled during growth
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ANTIOXIDANT ACTIVITY
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SOURCES OF VITAMIN A
I t was observed that thecontent of vi tamin A in a foodsources depends on i ts color .Therefore, the DARKER green- andDEEPER yel low -co lored ones haveMORE VITAMIN A. However, thevi tamin A ob tained from plants areno t eff ic ient ly ut i l ized as the onesobtained from animals (50% ofcarotenoids whi le 80% forpreformed vi tamin A ). An ind iv idualcan achieve recommended amountof vi tam in A by con sum ing a var ietyof foods from bo th animal and plant
sources (Serraon-Claudio et. al,2004).
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SUMMARY
Fat soluble vitamin Polyisoprene
compound Stored in the LIVER
and adipose tissues Present in food in 2
forms:1. Retinoids (ACTIVE)
ANIMAL source2. Carotenes
(INACTIVE)
PLANTsource
VITAMIN A
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8/31/2014
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FORM FUNCTION
RETINOL Reproductive function: Transcriptionalregulation of gene expression
RETINOLPHOSPHATE Maintenance of epithelial integrity andGlycoprotein synthesis
RETINOIC ACID Growth & Differentiation:
Transcriptional regulation of gene
expression
11- CIS RETINAL Vision in dim light (Rhodopsin)
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8/31/2014
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