Hypervitaminosis-A induces damage to:
Excess of vitamin A can lead to rupture of lysosomal membrane. The lysosome membrane can become more fragile: (1) when the cell is injured or deprived of oxygen ; (2) when excessive amounts of vitamin A (hypervitaminosis A) or iron are present; (3) in some cases of congenital vascular anomalies. Vitamin A is a fat soluble vitamin and belongs from a family of retinoids. They are essential for: 1. Vision 2. Reproduction 3. Growth 4. Maintenance of epithelial tissues Requirement for vitamin A: The RDA for adults is 1000 retinol equivalents (RE) for males and 800 RE for females. 1 RE= 1mg of retinol, 6mg of b-carotene or 12mg of carotenoids. Hypervitaminosis A: results from long-term supplement use (2 - 4 x RDA). Fatal dose is about 12 g. Acute toxicity Chronic toxicity Sho-term megadose (100 x RDA) ; symptoms disappear when intake stops Long-term megadose; possible permanent damage GI effects Headaches Blurred vision Poor muscle coordination Bone and muscle pain Loss of appetite Skin disorders Headache Dry skin Hair loss Increased liver size Vomiting Teratogenic: may occur with as little as 3 x RDA of preformed vitamin A. Tends to produce physical defect on developing fetus as a result of excess vitamin A intake Spontaneous aboion Bih defects Ref: Ghai 6th edition page 121 ; Handbook of Vitamins, edited by Janos Zempleni, 4th Edition, Page 562
Rough Endo-plasmic reticulum
Mitochondria
Microtubule
Lysosome