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# VITAMINS ## 2- Vitamin D (Calciferol) Vitamin D is a steroid ring. Ergosterol is the pro vitamin D in plant sources. 7-dehydrocholesterol is the pro vitamin D in human and animals. It has 2 vitamers D2 and D3. ### Activation of Vitamin D ``` ERGOSTEROL ↓ UV LIGHT ↓ CALCIFEROL (Vit D₂) ↓ LIV...

# VITAMINS ## 2- Vitamin D (Calciferol) Vitamin D is a steroid ring. Ergosterol is the pro vitamin D in plant sources. 7-dehydrocholesterol is the pro vitamin D in human and animals. It has 2 vitamers D2 and D3. ### Activation of Vitamin D ``` ERGOSTEROL ↓ UV LIGHT ↓ CALCIFEROL (Vit D₂) ↓ LIVER ↓ 25-OH-D ↓ CALCIFEDIOL (25-OH-D₃) ↓ KIDNEY ↓ CALCITRIOL (1,25(OH)₂D₃) ACTIVE FORMS ``` ### Function of Vitamin D: 1. Normalization of serum calcium and phosphate level 2. Normalization of bones by providing calcium and phosphate ### Vitamin D deficiency: 1. Rickets in children; bone deformities 2. Osteomalacia (softening of bones) in adults ### Excess vitamin D (vitamin D hypervitaminosis): Abnormal calcification of tissue and deposition of calcium and phosphate in the kidney (renal stones). ## 3- Vitamin E (tocopherols) There are four types of tocopherols: α, β, γ and δ. The most active form is α-tocopherol. ### Function: * Anti-sterility and Antioxidant. * Protection from atherosclerosis and heart disease (prevent oxidation of LDL). ### Deficiency: 1. RBCs hemolysis occurs due to oxidation (in premature infants). 2. Infertility.