Exam 3 Nutrition Concepts The Fat Soluble Vitamins A D E and K Chapter 11 Introduction Fat soluble vitamins differ from water soluble vitamins Require bile for digestion and absorption Travel through lymphatic system Many require transport proteins in bloodstream Excesses are stored Liver and adipose tissue Needed in periodic doses weeks or months Risk of toxicity is greater Review of Vitamins Water Soluble Vitamins vs Fat soluble Vitamins Absorption Transport Storage Water no storage excreted by kidney when consumed in excess Fat liver and adipose tissue Excretion Water soluble by the kidney Toxicity Fat D and A Water Niacin B6 Folate With masking toxicity of B12 All naturally occurring compounds with the biological activity of retinol the alcohol form of vitamin A Requirements Vitamin A and Beta Carotene Vitamin A rst fat soluble vitamin recognized Retinyl esters form found in animal foods Carotenoids form found in plant foods Vitamin C Retinoids in the body Retinol Retinal Retinoic acid Beta carotene pre cursor of Vitamin A most Conversion of Vitamin A Compounds Exam 3 Nutrition Concepts Vitamin A and Beta Carotene Roles in the Body Major roles Regulation of gene expression Vision Protein synthesis and cell differentiation Reproduction and growth Maintain health of epithelial tissues and skin Much converted back to cis form Some oxidized to Retinoic Acid L Vision Retinal forms part of rhodopsin Visual activity Epithelial tissue eyelids and sinus passageways Repeated small losses of retinal Need for replenishment with Vitamin A Protein synthesis cell differentiation Epithelial cells Goblet cells Secrete mucus to protect epithelial cells Sperm development Normal fetal development Growth of children Reproduction and growth Antioxidant Beta carotene Bone remodeling Review List the major roles of vitamin A in the body 1 Vision Skin Mucous membranes linings of GI tract lungs urinary bladder urethra reproductive organs Exam 3 Nutrition Concepts Retinol binding protein RBP carries Vitamin A in blood 2 Skin Protein synthesis and cell differentiation 3 Reproduction and Growth Additional antioxidant 90 stored in liver Adequacyofstores Proteinstatus Vitamin A and Beta Carotene Vitamin A De ciency Vitamin A status depends on Consequences of de ciency Infectious diseases Night blindness Blindness xerophthalmia Severity correlates with vit A de ciency Measles malaria lung diseases and HIV Risk of infectious diseases blindness death One of rst detectable signs of vit A de ciency aids diagnosis Inadequate supply of retinal to retina Lack of vitamin A at the cornea Develops in stages Severe Vitamin A de ciency is leading cause of preventable blindness with half a million preschool children losing sight each year Keratinization Change in shape size of epithelial cells Skin becomes dry rough and scaly Normal digestion and absorption of nutrients from GI tract falters Weakened defenses in respiratory tract vagina inner ear and urinary tract Free vitamin A damages cells Vitamin A and Beta Carotene Vitamin A Toxicity Develops when binding proteins are loaded Toxicity is a real possibility Beta carotene Preformed vitamin A from animal sources Forti ed foods Supplements Children are most vulnerable Found in many fruits and vegetables Inef cient conversion Exam 3 Nutrition Concepts Antioxidant becomes pro oxidant Alcohol consumption and tobacco use effects of supplementation Yellow skin not harmful Over consumption from food Over consumption from supplements Bone defects Interferes with vitamin D s ability to maintain blood calcium Birth defects May weaken bones Cell death in the spinal cord Osteoporosis Teratogen substance that causes abnormal fetal development and birth defects Prescription medications effective but require medical supervision due to possible side effects Accutane isotretinoin Vitamin A relative Retin A prescription for topical use Fights acne and wrinkles lightens pigmented skin Review De ciency is common in developing countries Vit A offers protection in the following illnesses HIV Malaria Measles Lung Disease warranting supplementation for infants and children with such conditions Supplements are also warranted when a de ciency has caused night blindness one of the rst detectable signs of vit A de ciency Vitamin A and Beta Carotene Recommendations Supplements often measured in International Units IU Expressed as retinol activity equivalents RAE mcg IU 1 mcg retinol 1 RAE 12 mcg beta carotene 1 RAE Vitamin A Measures 1 mg RAE 1 mcg retinol 2 mcg beta carotene 12 mcg beta carotene 24 mcg other vit A precursor carotenoids 1 IU retinol 3 mcg retinol 3 mcg RAE Exam 3 Nutrition Concepts Vitamin A and Beta Carotene Food sources Rich source frequent consumption can cause toxicity of active form Animal sources retinoids Milk milk products butter skim might not have these because stored in fat and skim is fat free Eggs Milk must have 1200 IU per quart level of vit A in whole milk Margarine forti ed to have level of butter Liver sh liver oils Food sources Plant sources carotenoids Beta carotene Rich deep yellow almost orange compound Cantaloupe carrots sweet potatoes Masked by chlorophyll in dark green leafy vegetables Spinach broccoli Review Plants contain carotenoids vitamin A precursors Only a few have vitamin A activity the one with the greatest vitamin A activity is beta carotene It is found in fruits vegetables food groups orange in color such as cantaloupe carrots sweet potatoes It is also found in foods dark green in color such as spinach broccoli The chlorophyll in these foods masks the color of beta carotene Beta carotene is less likely to lead to toxicity due to dietary intake than pre form Vitamin A Supplements however can lead to toxicity with both forms Vitamin D Keep in mind Liver or kidney disease would interfere with Vitamin D synthesis Depends where you live if Vitamin D is an essential nutrient Not an essential nutrient if adequate sunlight Activation of vitamin D Two hydroxylation reactions in the Body synthesizes from sunlight Requires precursor that body makes from cholesterol Liver Kidneys Vitamin D Roles in the Body Active form of vitamin D is a hormone the body to respond a compound manufactured by one part of the body that travels through the blood and causes another part of Dark skin breastfeeding without supplementation lack of sunlight not using forti ed milk major issue is it Exam 3 Nutrition Concepts Binding protein carries it to target organs Maintain
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