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Vitamins A, D, E, K by Dr. Anurag Yadav
- 1. VITAMINS MNR MEDICAL COLLEGE & HOSPITAL Dr Anurag Yadav MBBS, MD Assistant Professor Department of Biochemistry Instagram page –biochem365 YouTube – Dr Biochem365 Email: dranurag.y.m@gmail.com
- 2. Vitamins May be defined as organic compounds required in small quantities necessary for growth and maintenance of good health in human beings
- 3. Classification Fat soluble vitamins Fat soluble Along with lipids , requires bile salts Carrier proteins present Stored in liver Not excreted Deficiency manifests only when stores are depleted Water soluble vitamins Water soluble Simple absorption No carrier proteins No storage Excreted Manifested rapidly as there is no storage
- 4. Hypervitaminosis may result Unlikely since vitamins are excreted
- 5. VITAMIN A
- 6. VITAMIN A – structure Six membered ring with 11 carbon containing side chain
- 7. Chemistry Provitamin form is – beta carotene (HAS 2 MOLECULES OF RETINAL ) Biologically active forms Retinal Retinol Retinoic acid Its heat stable and light sensitive
- 8. Vitamin A Sources Animal sources – fish liver oils, Vegetable and animal sources – carrot, papaya , peach , tomatoes (red and yellow) Palm oil is rich in carotenoids
- 9. ABSORPTION BETA CAROTENE is cleaved in the lumen of intestine to retinal (beta carotene dioxygenase) Retinal is reduced to retinol by retinal aldehyde dehydrogenase This is then incorporated in to chylomicrons and stored in liver Retinol is transported from liver to other sites by (RBP)retinol binding protein in other tissues its bound to CRBP
- 10. Biochemical functions 1. Vision- WALDS VISUAL CYCLE rods(for vision in dim light ) and cones(colour vision) Pigment in rods-rhodopsin or visual purple In cones- porphyropsin iodopsin cyanopsin
- 12. 2. Antioxidant properties protect against cancer and heart disease 3.Maintenace of normal epithelium and skin 4. Metabollic role-Glycoprotein synthesis for mucous secretions Biosynthesis of cholestrol Controls gluconeogenesis in liver 5. normal reproduction 6. retinoic acid for Growth and differentiation
- 14. REQUIREMENT 1000 μg/day 1 RE= 1MICROGRAM OF RETINOL
- 15. Causes of deficiency Impaired absorption of lipids Impaired storage in liver disease Failure to synthesize RBP Deficiency of particular enzymes Decreased intake
- 16. Deficiency manifestations Manifestations Early symptoms Night blindness Xerophthalmia Later as disease progresses Bitot’s spots Keratomalacia –affects retina Conjunctival xerosis Skin and mucous membrane lesions Failure of skeletal growth
- 17. Skin diseases Abnormalities of reproduction
- 18. Hypervitaminosis – ,HAIR LOSS BONE PAIN HEADACHE PEELING OF SKIN HEPATOMEGALY NAUSEA, VOMITING
- 19. Therapeutic use of vitamin A- 1. REDUCES COMLICATIONS OF MEASLES 2. PRECANCEROUS LESIONS RESPOND TO CAROTENOIDS 3. AS TOPICAL CREAMS
- 21. VIT D is also called CALCIFEROL due to role in Ca metabolism Also called ANTIRACHITIC FACTOR as it prevents rickets Also called sunshine vitamin
- 22. STRUCTURE NATURALLY PRODUCED VIT D 3- CHOLECALCIFEROL LAB SYNTHESISED VIT D 2 - ERGOCALCIFEROL
- 23. cholesterol 7 - dehydrocholesterol Cholecaiciferol Vit D3 Ergosterol From plant Ergocalciferol Vit D2
- 25. Vitamin D Sources Exposure to sunlight Fish liver oil, fish, egg yolk RDA Pre-school children – 400 IU Children and adults – 200 IU Pregnancy and lactation – 400 IU Old age – 600 IU
- 26. ABSORPTION Skin liver Circulated in blood bound to vit d binding proteins synthesized by liver Dietary vit d is absorbed from duodenum along with lipids Carried by plasma as a constituent of chylomicrons Taken to liver as chylomicron remnants Cholecalciferol- PROHORMONE
- 27. ACTIVE FORM 1:25 DIHYDROCHOLECALCIFEROL Steps in synthesis vit D 3 MIT of liver 25 hydroxycholecalciferol kidney 1α HYDROXYLASE 24 HYDROXYLASE 1:25 dihydrocholecalciferol 24:25 dihydrocholecalciferol
- 28. REGULATION OF ACT VIT D ACTIVITY OF 1α HYDROXYLASE IS REGULATED BY 1. PARATHYROID HORMONE 2. PLASMA Ca 3. Insulin ,GH estrogen increase syn of activated form INHIBITOR OF 1α HYDROXYLASE IS THE ACTIVE FORM OF VIT D
- 29. Formation of vitamin D
- 30. Biochemical functions CALCITRIOL INTESTINE BONES KIDNEY ↑CALCIUM AND PHOSPHORUS ABSORPTION INCREASES MINERALISATION OF BONES ↑ CALCIUM AND PHOSPHORUS REABSORPTION
- 31. OTHER FUNCTIONS CELL GROWTH AND DIFFERENTIATION OF IMMUNOREGULATORY CELLS EPIDERMAL CELLS MALIGNANT TUMOUR CELLS ACTIVE FORM OF VIT D DEPRESSES IMMUNE SYSTEM
- 32. Vitamin D deficiency Causes No exposure to sunlight Secondary to malabsorption of vitamin Secondary to abnormality of vitamin D activation Secondary to abnormalities in renal absorption of phosphates
- 33. Clinical features Rickets – in children Bone deformities Knock knee Bow legs Frontal bossing Ricketic rossary Harissons sulcus Pigeon chest
- 35. Osteomalacia -in adults Bone pain Bone fracture osteoporosis Biochemical parameters Slight decrease in calcium and phosphorus Serum alkaline phosphatase increased
- 36. Different types of rickets Vitamin D deficiency rickets- Vitamin D resistant rickets Hypophosphatemic rickets Renal rickets
- 37. Hypervitaminosis D >1500 IU for long periods Clinical features Weakness Polyuria Polydipsia Difficulty in speaking Confusion Weight loss Hypercalcemia,hypokalemia,metabolic alkalosis Calcification of soft tissues in vascular and renal tissues
- 38. VITAMIN E
- 39. STRUCTURE Chromane ring / tocol with an isoprenoid side chain TOCOPHEROL-αβγδ OF WHICH ALPHA IS MOST POTENT
- 40. Sources Vegetable oils- RICH SOURCES- CORN AND SOYA OIL GOOD SOURCES- PALM OIL OLIVE AND COCONUT OIL ARE RELATIVELY POOR
- 41. Vitamin E RDA Males – 10mg Females – 8mg Pregnancy – 10mg Lactation – 12mg >60years – 12mg
- 42. ABSORPTION Absorbed from the small intestine along with lipids Incorporated into chylomicrons and delivered to tissues Then taken to liver in the form of chylomicron remnants From liver exported to target tissues in the form of VLDL
- 43. Biochemical role Most powerful antioxidant Reduces the risk of MI by reducing oxidation of LDL Slows progression in Alzheimer’s disease Boosts immune response Protects erythrocyte membrane from oxidants Hypervitaminosis > 1000 IU Tendency to haemorrhage
- 45. DEFICIENCY ITS RARE FEATURES 1. HAEMOLYTIC ANAEMIA 2. Neuropathy premature infants with low birth weight are most commonly deficient.
- 46. VITAMIN K
- 47. STRUCTURE 1. VITAMIN K 1(PHYLLOQUINONE) from plants 2. VITAMIN K 2(MENAQUINONE) syn by microorganisms 3. VITAMIN K 3(MENADIONE)- SYNTHESIZED FORM
- 48. Vitamin K Sources Green leafy vegetables Intestinal bacterial synthesis RDA 50-100mg/day
- 49. Chemistry Naphthoquinone derivatives,with a long isoprenoid side chain. Absorption and storage Bile salts are required for normal absorption and are stored in liver.
- 50. Biochemical functions Coagulation – required for the activation of clotting factors II,VII,IX,X.They undergo post translational modification. Functional activity of C reactive protein, osteocalcin and structural proteins of kidney ,lung,spleen
- 51. Vitamin K deficiency Causes Malabsorption of lipids Prolonged antibiotic therapy and GI infections C/F Haemorrhagic disease of the new born In children and adults – bruising tendency,echymotic patches,mucous membrane haemorrhage,post traumatic bleeding,internal bleeding
- 52. Prolonged prothrombin time and delayed clotting time Warfarin and dicoumarol will competitively inhibit vitamin K Hypervitaminosis K Administration of large quantities of vitamin K Hemolysis,Hyperbilirubinemia,Kernicterus and brain damage