Introduction to Hematopoietic Vitamins HMIM224

Study Notes

HMIM224 Block focuses on vitamins crucial for blood formation (hematopoietic) and preventing bleeding (antihemorrhagic)
Objectives of the lectures include:
- Introduction to vitamins as micronutrients
- Categorization of vitamins (water-soluble and fat-soluble)
- Biochemistry of water-soluble vitamins and their role in red blood cell formation
- Biochemistry of fat-soluble vitamins
- Role of vitamin K in blood coagulation

Vitamins are categorized as water-soluble or fat-soluble based on their solubility properties
Key water-soluble vitamins: Thiamine (B1), Riboflavin (B2), Niacin (B3), Pantothenic Acid (B5), Pyridoxine (B6), Biotin (B7), Folic Acid (B9), Cobalamin (B12), and Ascorbic Acid (C)
Key fat-soluble vitamins: Retinol (vitamin A), Cholecalciferol (vitamin D), Tocopherol (vitamin E), and Phylloquinone (vitamin K)

Absorption: Require carriers (like chylomicrons) to be absorbed into the lymph, then blood
Transport: Transported in the blood with proteins
Storage: Stored in body tissues with fats and cells
Excretion: Harder to excrete through urine, stored with fats in cells
Toxicity: More prone to toxicity due to storage in body tissues
Requirements: Needed less frequently, often weekly

Pyridoxine (B6): Coenzyme for ALA synthase (heme synthesis); detailed in GIT block
Folic Acid (B9): Essential for DNA synthesis, cell division, and red blood cell maturation
Cobalamin (B12): Crucial for DNA synthesis and nerve myelination. Also converts homocysteine to methionine.
Ascorbic Acid (vitamin C): Helps in iron absorption and antioxidant

Chemistry: Its structure is shown in the infographic
Sources: Found in vegetables, liver, and meat; susceptible to cooking degradation
Synthesis: Not synthesized by humans, but by microorganisms
Active Form: Tetrahydrofolate (THF): (activation occurs in human cells)
Function: Essential for purines and thymidine nucleotides for DNA synthesis, important for cell maturation (especially erythroid progenitors)
Deficiency Causes: nutritional deficiencies, GIT disease, medication like methotrexate
Deficiency Effect: Megaloblastic anemia.

Sources: Animal products (liver, meat, chicken), daily requirements of 5ug, stored in large numbers (5mg) in the liver
Coenzyme Forms: Adenosylcobalamin and Methylcobalamin (active forms)
Absorption: Requires intrinsic factor produced by the stomach for absorption in the small intestine (lower ileum)
Importance: Vital for DNA synthesis, nerve myelination

Dietary deficiency (vegetarians):
Malabsorption (problems with intrinsic factor production, gastric bypass, intestinal issues)

Chemistry: Its structure is displayed in the materials
Sources: Found in various fruits and vegetables, dietary sources are provided in the notes
Function: Reducing agent, aids iron absorption, antioxidant, coenzyme for hydroxylases in collagen synthesis, critical for wound healing
Deficiency: Scurvy (fatigue, sores, loose teeth, easy bruising)

Types: Vitamin K1 (phylloquinone—plant sources) and Vitamin K2 (menaquinone—synthesized by intestinal bacteria/animals)
Absorption: Bile (from the liver) essential for fat-soluble vitamin absorption
Role in Hematopoiesis: Necessary for final stage in the synthesis of coagulation factors (VII, IX, X, prothrombin and anticoagulation, proteins). Activates factors via carboxylation of glutamate residues which permits calcium and phospholipid binding.
Deficiency: Hemorrhagic (bleeding) disease of the newborn, a possible source being lack of gut colonization in newborns.