Fat-Soluble Vitamins
| Vitamin | Function | Deficiency | Toxicity/Notes |
|---|
| A (Retinol) | Antioxidant, vision (retinal), epithelial differentiation. | Night blindness, xerosis cutis, corneal degeneration, immune suppression. | **Teratogenic** (cleft palate). Chronic: Alopecia, hepatomegaly, pseudotumor cerebri. |
| D (Calciferol) | Ca/PO4 absorption, bone mineralization. | Rickets (kids), Osteomalacia (adults), Hypocalcemic tetany. | Hypercalcemia, hypercalciuria. Seen in Sarcoidosis (macrophage activation). |
| E (Tocopherol) | Antioxidant (protects RBCs). | Hemolytic anemia (acanthocytosis), posterior column demyelination (ataxia). | Interferes with Vitamin K (bleeding). |
| K (Phytomenadione) | Gamma-carboxylation of clotting factors (II, VII, IX, X, C, S). | Neonatal hemorrhage (elevated PT/aPTT). | Given at birth (sterile gut). Warfarin antagonist. |
Water-Soluble Vitamins
| Vitamin | Function/Cofactor | Deficiency |
|---|
| B1 (Thiamine) | Pyruvate DH, Alpha-KG DH, Transketolase, Branched-chain AA DH. | Wernicke-Korsakoff (Confusion, Ophthalmoplegia, Ataxia). Dry Beriberi (polyneuritis). Wet Beriberi (Cardiac failure). |
| B2 (Riboflavin) | FAD/FMN (Redox). | Cheilosis, **Corneal vascularization**. |
| B3 (Niacin) | NAD+/NADP+. From Tryptophan. | **Pellagra** (Diarrhea, Dementia, Dermatitis). Hartnup disease. |
| B5 (Pantothenic) | Coenzyme A (CoA). | Adrenal insufficiency, Burning feet syndrome. |
| B6 (Pyridoxine) | PLP. Transamination (ALT/AST), Heme synthesis (ALA synthase). | Convulsions, Neuropathy (Isoniazid), Sideroblastic anemia. |
| B7 (Biotin) | Carboxylation (Pyruvate, Acetyl-CoA, Propionyl-CoA). | Dermatitis, Alopecia. Caused by raw egg whites (Avidin). |
| B9 (Folate) | THF. DNA/RNA synthesis. | Megaloblastic anemia, NTDs. No neurologic signs. High Homocysteine, Normal MMA. |
| B12 (Cobalamin) | Methionine synthase, Methylmalonyl-CoA mutase. | Megaloblastic anemia, Subacute Combined Degeneration. High Homocysteine AND MMA. |
| C (Ascorbic) | Antioxidant, Collagen hydroxylation, Dopamine beta-hydroxylase. | Scurvy (swollen gums, bruising, corkscrew hair), Poor wound healing. |
High-Yield Mnemonics
The B-Vitamin Numbering:
"The Rhythm Nearly Proved To Be Contagious"
Thiamine (1), Riboflavin (2), Niacin (3), Pantothenic (5), Pyridoxine (6), Biotin (7), Cobalamin (12).
B Cofactors & ATP:
B1: ATP (Alpha-KG, Transketolase, Pyruvate DH)
B2: FAD = 2 ATP
B3: NAD = 3 ATP
Clotting Factors:
"1972" (10, 9, 7, 2) + C and S require Vitamin K.
Critical Biochemistry & Interactions
- Folate Trap: B12 deficiency traps folate as N5-Methyl-THF.
- Isoniazid: Depletes B6 (sideroblastic anemia, neuropathy).
- Methotrexate: Inhibits DHFR (folate antagonist).
- Orlistat: Blocks fat absorption -> ADEK deficiency.
- Alcoholics: Give Thiamine BEFORE Glucose to prevent Wernicke's.