Vitamin A
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  • 1. By Payal Patel
  • 2.  The word "vitamin" comes from the Latin word vita, means "life".  Vitamins are chemicals found in very small amounts in foods.  “Vitamins have been defined as organic compounds which are required in minute amounts to maintain normal health of organisms’.
  • 3.  Introduction  Classification  Chemistry  Metabolism  Biochemical  Sources  RDA  Deficiency  Toxicity functions
  • 4. FAT SOLUBLE A D E K Water soluble  B1- Thiamine  B2- Riboflavin  B3– Niacin  B5 – Pantothenic acid  B6 –Pyridoxine  B8 – Biotin  B 9 -Folic acid  B12 -CyanoCobalamin  C (Ascorbic acid)
  • 5.  They  Bile are soluble in fat. salts are essential for there absorption.  They are generally stored in liver.  They are not excreted in urine.
  • 6. VITAMIN-A
  • 7. CHEMISTRY • • • • Fat soluble vitamin Acive form – Retinoids -Animal Pro-formed - β carotene – Plant It contain β ionone ring
  • 8. Retinoids • Retinol • Retinal • Retinoic acid
  • 9. • Retinol (vitamin A alcohol) :
  • 10. Retinal (vitamin A aldehyde) : • This is an aldehyde form obtained by the oxidation of retinol. • Retinal and retinol are interconvertible.
  • 11. Retinoic acid (vitamin A acid) : • produced by the oxidation of retinal. • However, retinoic acid cannot give rise to the formation of retinal or retinol.
  • 12. Beta-Carotene (provitamin A) : • Found in plant foods. • lt is cleaved in the intestine to produce two moles of retinal. • ln humans, this conversion is inefficient, hence beta-carotene possesses about one-sixth vitamin A activity compared to that of retinol.
  • 13. Metabolism • Absorption: with help of bile salt in intestine • Transport: via lymph with help of chylomicron • Storage : liver in form of Retinyl palmitate • Free retinol is highly active but toxic & therefore transported in blood stream in combination with retinol binding protein
  • 14. FUNCTIONS  Vision  Epithelial cell "integrity’  Reproduction  Resistance to infectious disease  Bone remodeling  Growth & cell differntiation
  • 15. vision • Rhodopsin is congucated protein, light sensitive pigment within rod and cone cells of the retina.  Rods are involved in dim light vision  Cones are responsible for bright light & colour vision  The colour vision is governed by colour sensitive pigments porphyropsin (red), iodopsin (green) and cyanopsin (blue).
  • 16. Wald’s visual cycle
  • 17. Dietary Sources of Vitamin A Plant sources • • • • • • Carrots Mangoes Papaya Spinach Broccoli Dark green vegetables Animal sources leafy • • • • • • • liver Cod liver oil Fish oil Eggs Fish Milk Milk products
  • 18. Daily requirment Men and women – 750-1000 μg. Pregnancy and lactation – 1000 μg. Infants – 350 μg. Children – 400-600 μg.
  • 19. DEFICIENCY  Preschool children with decreased intake  Alcoholism  Liver disease (limits storage)  Fat malbsorption
  • 20. The signs of vitamin A deficiency Ocular  Night blindness.  xerophthalmia  bitot’s spot  keratomalacia Extra ocular  Retarded growth  Skin disorders  Effect on reproductive organs.  Effect on bone
  • 21. Night blindness  Lack of vitamin A causes night blindness or inability to see in dim light as a result of inadequate pigment in the retina.  Earliest symptom
  • 22. XEROPHTHALMIA • Conjunctiva become dry, thick and wrinkled
  • 23. Bitot’s spot • Grayish white triangular spots in conjunctiva
  • 24. KERATOMALACIA • Infection leads to corneal ulceration and total blidness
  • 25. Skin and Epithelial cells: Phrynoderma/toad skin Keratinization of GI, respiratory tracts Reproductive system: Degeneration of germinal epithelium- infertility Growth retardation
  • 26. Hypervitaminosis A Symptoms and signs: •Fatigue,malaise,anorexia, • Vomiting,headache •Dermatitis •Skeletal decalcification •Tenderness of long bones •Hepatomegaly
  • 27. Thank you