VITAMIN-K

2. VITAMIN-K

3. Different forms of Vitamin K Vitamin K1 (phylloquinon) – plant origin Vitamin K2 (menaquinon) – normally produced by bacteria in the large intestine

4. Major Functions • K1 a K2 are used differently in the body • K1 – used mainly for blood clotting • K2 – important in non-coagulation actions - as in metabolism and bone mineralization, in cell growth, metabolism of blood vessel walls cells.

5. CHEMICAL STRUCTURE Vitamin K1 Phylloquinone Vitamin K2 Menaquinone Menadione (Synthetic) Synthetic derivatives of Vit.K

6. SOURCES OFVITAMIN K • Kidney and Liver • Spinach • Green cabbage • Turnip • Parsley • Lettuce • Beef liver • Green tea

7. FOODS RICH IN VITAMIN K: VITAMIN K Green cabbage Turnip Spinach Parsley Beef liver Green tea

8. RECOMMENDED DAILY REQUIREMENT • New born: 500- 1000 μg once • Commercial infant formula contain 50- 125 μg/day • 1- 6 Months: 5 mg/day • 6- 12 Months: 15 mg/day • Adult: 80 mg/Kg (body weight) / day

9. Absorption and metabolism About half of the Vit K present in the human diet is derived from green leafy vegetables, and about half is synthesized by the gut flora. As it is fat soluble, requires the presence of bile for its absorption, which occurs mostly in the upper part of the small intestine.

10. METABOLISM OF VITAMIN K • 70% of Vit. K3 ( menadione) excreted in urine in 24 hr in the form of sulphate, phosphate and glucuronic acid conjugate. • Small % excreted in faces as glucuronic acid conjugate. • Vit K2 and K3 undergo slower metabolism to shorten the side chain to 5- 7 carbons carboxylate.

11. SYMPTOMS OF VITAMIN K DEFICIENCY • Uncontrolled internal bleeding. • Cartilage calcification and malformation of developing bone. • Deposition of insoluble calcium salts in the arterial vessel walls.

12. Factors needed to prevent vitamin K deficiency: a. Normal diet containing the vitamin. b. Presence of bile in the intestine. c. A normal intestinal uptake or absorption. d. A normal liver i.e. no interference with vitamin K metabolism or use of vitamin K antagonists therapeutically or accidently. e. Heavy alcohol consumption impairs the liver’s ability to produce vitamin K-dependent coagulation factors and impair recycling of vitamin K.

13. Who is at a greater risk of developing vitamin k deficiency • Newborn infants who are exclusively breastfed are susceptible to abnormal bleeding due to vitamin K deficiency. • Breast milk contains very little vitamin K and the immature liver of the newborn does not synthesize the vitamin K-dependent clotting factors efficiently.

14. VITAMIN K DEPENDENT PROTEINS factor II (prothrombin) factor VII (proconvertin) factor IX (thromboplastin component) factor X (Stuart factor) protein C & protein S Protein Z

15. ALSO, BECAUSE • The newborn’s colon is sterile for the first few days after birth, no bacterial synthesis of vitamin K occurs in the colon. • To reduce the risk of vitamin K deficiency, most babies receive intramuscular vitamin K at birth.

16. Vitamin K Dependent Coagulation Certain clotting factors/proteins require calcium to bind for activation Calcium can only bind after gamma carboxylation of specific glutamic acid residues in these proteins The reduced form of vitamin K2 (vitamin KH2) acts as a cofactor for this carboxylation reaction. These proteins are known as “Vitamin K dependent” proteins

17. DRUG INTERACTION WITH VITAMIN K • Some interactions may increase the need for vitamin K: • Antibiotics: Prevent absorption and kill normal bacterial flora. • Anti convulsants e.g. Phenytoin : Affect Vit K metabolism.

18. THANKS

19. The role of vitamin B12 within the body Vitamin B12 is required as coenzyme for two metabolic reaction:  •      (1) Isomerization of L-methylmalonyl CoA to succinyl CoA. This is important substrate in Hb synthesis. •      (2) Methylation of homocystine to methionine. This step is important in intracellular synthesis of folate coenzyme.