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home - Nutrition - Vitamins - Vitamin A Written by Dr Sebastian Zeki

Vitamin A

Occurs with single doses of >660,000 units (>200 mg) Symptoms include nausea, vomiting, vertigo, and blurry vision. Toxic dose10 x RDA (10,000 micrograms of retinol or 33,000 IU) Toxicity of vitamin A increased byLiver and kidney diseaseAlcoholismSome drugs, such as tetracyclines. Vitamin A Excess Impairment of the phagocytes and T cells. Xerophthalmia - due to inadequate function of the lacrimal glands Clinical: Night blindness and Bitot's spots (areas of abnormal squamous cell proliferation and keratinization of the conjunctiva), progressing to corneal xerosis and keratomalacia. Repalcement of hair follicles with mucus-secreting glands. Poor bone growth ReplacementTo prevent clinical vitamin A deficiency, Vitamin A supplements can be distributed at 4 to 6 month intervals at the following doses:Infants < 6 months of age -Non breast-fed: 50,000 IU orally Breast fed: 50,000 IU orallyInfants 6 to 12 months of age: 100,000 IU orallyChildren >12 months of age: 200,000 IU orallyMothers: 200,000 IU orally, within 8 weeks of deliveryPregnant women only get10,000 IU daily or 25,000 IU weekly (teratogenicity at high doses) Vitamin A- Clinical manifestations of deficiency Acute toxicity Chronic toxicity SymptomsDry skin, Nausea,HeadacheFatigue, IrritabilityHepatomegaly with stellate cell proliferation (lead to cirrhosis)AlopeciaHyperostosis, osteoporosisIncreased cerebrospinal fluid pressure (pseudotumor cerebri)Teratogenic in first trimester. Vitamin A- Clinical manifestations of deficiency and Excess Written by Dr Sebastian Zeki

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