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Vitamin A
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Definition Vitamin A is a generic term for a large number of related compounds Retinol (an alcohol) Retinal (an aldehyde) Retinoic acid Carotenoids
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Function Vision Regulation of gene expression
Maintenance of epithelial tissue Immunity Growth and development Red blood cell production Prevention of cancer
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Males: mcg/day (IU/day) Females: mcg/day (IU/day)
Recommended Dietary Allowance (RDA) for Vitamin A as Preformed Vitamin A (Retinol) Life Stage Age Males: mcg/day (IU/day) Females: mcg/day (IU/day) Infants 0-6 months 400 (1333 IU) 7-12 months 500 (1667 IU) 500 (1667 IU) Children 1-3 years 300 (1000 IU) 300 (1000 IU) 4-8 years 9-13 years 600 (2000 IU) Adolescents 14-18 years 900 (3000 IU) 700 (2333 IU) Adults 19 years and older Pregnancy 18 years and younger - 750 (2500 IU) 19-years and older 770 (2567 IU) Breastfeeding 1,200 (4000 IU) 19-years and older 1,300 (4333 I
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Good dietary sources of vitamin A
Best sources include: beef liver carrots (as beta-carotene) mustard greens (as beta-carotene) eggs apricots (as beta-carotene) Note that beta-carotene is much less toxic in higher doses than is the preformed animal forms of vitamin A
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Food Serving Vitamin A, RAE Vitamin A, IU Retinol, mcg Retinol, IU Cod liver oil 1 teaspoon 1,350 mcg 4,500 IU Fortified breakfast cereals 1 serving mcg IU Egg 1 large 91 mcg 303 IU 89 mcg 296 IU Butter 1 tablespoon 97 mcg 323 IU 95 mcg 317 IU Whole milk 1 cup (8 fl ounces) 68 mcg 227 IU 2% fat milk (vitamin A added) 134 mcg 447 IU Nonfat milk (vitamin A added) 149 mcg 500 IU Sweet potato 1/2 cup, mashed 959 mcg 3,196 IU Carrot (raw) 1/2 cup, chopped 385 mcg 1,283 IU Cantaloupe 1/2 medium melon 466 mcg 1,555 IU Spinach 1/2 cup, cooked 472 mcg 1,572 IU Squash, butternut 572 mcg 1,906 IU
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Quantity Bioconverted to Retinol
Retinol activity equivalency (RAE) ratios for beta-carotene and other provitamin A carotenoids Quantity Consumed Quantity Bioconverted to Retinol RAE ratio 1 mcg of dietary or supplemental vitamin A 1 mcg of retinol* 1:1 2 mcg of supplemental beta-carotene 1 mcg of retinol 2:1 12 mcg of dietary beta-carotene 12:1 24 mcg of dietary alpha-carotene 24:1 24 mcg of dietary beta-cryptoxanthin 24:1 *One IU is equivalent to 0.3 mcg of retinol, and one mcg of retinol is equivalent to 3.33 IU of retinol.
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vitamin A deficiency Symptoms Dry, hard skin
Dry cornea and eventual blindness (Xerophthalmia) Night blindness (insufficient retinal for rhodopsin formation) Impaired immune function Deficiency also causes a decrease in appetite and poor growth
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Cause of deficiency Insufficent intake(poverty,low income,…)
Lack of food sources of V.A Low fat diet Malabsorption(surgery,parasite,…) Increasedneed(pregnancy,breastfeeding,…) Insufficent Supplemental feeding Infectious disease
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Deficiency in children:
250 millions preschool children have subclinical deficiency The most incidencecause of blindness in developing countries( children in year) If 1% children(2-6 years old)with night blindness or 10% children (6 months-6 years )had serum retinol below 7%micromol/l that population had health problem. Improve of V.A level in infant lead to decrease of 23% mortality
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Control of VADD 1.Breastfeeding 2.Supplementation 3.Fortification
4.Food variety 5.Control of infectious disease¶site
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Supplement in severeV.A.D populatin
Infant(<6months) IU (not fed breastmilk or their mothers not take V.A supplement) Infant(6-12months ) IU (every 4-6 months) Children(>1 year) IU Children mega dose (withmeaslse,diahrea,pneumonia& severe malnutrition) Mothers mega dose (during 8 week after delivery)
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Supplement in low V.A.D populatin
Children(<2 years) IU/daily Pregnancy IU/daily (from4 months- delivery) 2500IU/weekly
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Toxicity Symptoms nausea, headache, fatigue, loss of appetite, dizziness, and dry skin, in pregnancy birth defects Signs of chronic toxicity dry itchy skin, loss of appetite, headache, and bone and joint pain Severe hypervitaminosis A liver damage, hemorrhage, and coma
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Tolerable Upper Level of Intake (UL) for Preformed Vitamin A (Retinol)
Age Group UL in mcg/day (IU/day) Infants 0-12 months 600 (2,000 IU) Children 1-3 years Children 4-8 years 900 (3,000 IU) Children 9-13 years 1,700 (5,667 IU) Adolescents years 2,800 (9,333 IU) Adults 19 years and older 3,000 (10,000 IU)
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