CHAPTER 12 FAT-SOLUBLE VITAMINS

LEARNING OUTCOMES Define the word vitamin and list 3 characteristics of vitamins as a group Classify the vitamins according to whether they are fat or water-soluble List 3 important food sources for each fat- soluble vitamin List the major functions for each fat-soluble vitamin 2

LEARNING OUTCOMES Describe the deficiency symptoms for each fat-soluble vitamin and state the conditions in which deficiencies are likely to occur Describe the toxicity symptoms caused by excess consumption of certain fat-soluble vitamins Evaluate the use of vitamin and mineral supplements with respect to their potential benefits and risks to health 3

VITAMINS: ESSENTIAL DIETARY COMPONENTS Two categories Fat-soluble: Vitamins A, D, E and K Water-soluble: Vitamin B complex (8) and C Compare and Contrast Absorption of vitamins Malabsorption of vitamins Transport of vitamins Storage of vitamins in the body 4

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VITAMIN A Retinoids Active form: preformed Vitamin A Retinal, retinol and retinoic acid Dietary sources: liver, fish oils, fortified dairy products and eggs Caroteinoids Provitamins-can be converted to Vitamin A Dietary sources: dark green and yellow orange vegetables and fruits 6

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EQUIVALENTS Used for some vitamins when there are multiple forms of the vitamin so there is one common unit 9

VITAMIN A NEEDS RDA Men 900 micrograms retinol activity equivalent (RAE) Women 700 micrograms RAE Daily Value (used on packaging) Approximately 1,000 micrograms Average current intake meets DRI 10

11 Which are vitamin A and which are beta carotene?

ABSORPTION, TRANSPORT AND EXCRETION OF VITAMIN A Absorption Packaged with chylomicrons and transported via the lymphatic system Transport Retinoids-bound to retinol binding protein Carotenoids-carried by VLDL Excretion Small amount in urine 12

FUNCTIONS OF VITAMIN A (RETINOIDS) Growth and Development Embryonic development Epithelial cells and mucus production in lungs, trachea, skin, GI tract Immune Function Maintains the ephithelium Increased infections w/vit A deficiency Dermatology Topical and oral medications 13

FUNCTIONS OF VITAMIN A (RETINOIDS) 14

FUNCTIONS OF VITAMIN A (RETINOIDS) 15

FUNCTIONS OF CAROTENOIDS Provitamin A activity Beta carotene (most Vitamin A activity of the carotenoids) NOT toxic Other health benefits Cataracts Lung cancer Macular degeneration Other carotenoids Lutein and zeaxanthin Lycopene 16

VITAMIN A DISEASES Deficiencies Night blindness Xerophthalmia (permanent blindness) Follicular hyperkeratosis Impaired growth Increased infections Increased transmission of maternal/fetal HIV 17

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VITAMIN A DISEASES Toxicities Hypervitaminosis A Upper limit-3000 micrograms/day retinol (not carotenoids) Appears w/ chronic supplement use at 5-10x the RDA Acute (100x RDA for a few days) GI upset, headache, poor muscle coordination Chronic (chronic use of 10x RDA) Joint pain, liver damage, coma, death Teratogenic 20

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VITAMIN D “Conditional” or prohormone Requirement-sunlight 2-3 times a week for minutes Skin formation: In skin, sunlight (UV light) changes 7-dehydrocholesterol (made from cholesterol) to vitamin D3 Whether it is made in the skin or ingested, D3 is converted to form 25-hydroxycholecalciferol or 25(OH)D) in the liver. Once made, the product is released into the plasma, where it binds to vitamin D binding protein. 25(OH)D travels to liver and kidney and converted to bio active form-1,25(OH) 2 D (ligand for VDR, responsible for most actions of vitamin D) 22

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Table 2: Recommended Dietary Allowances (RDAs) for Vitamin D [1] AgeMaleFemalePregnancyLactation 0–12 months*400 IU (10 mcg) 1–13 years600 IU (15 mcg) 14–18 years600 IU (15 mcg) 19–50 years600 IU (15 mcg) 51–70 years600 IU (15 mcg) >70 years800 IU (20 mcg) 24

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VITAMIN D NEEDS The new reference intakes (RDA) for vitamin D are based on amount need to maintain serum 25- hydroxyvitamin D level of 20 ng/mL (for optimal bone and overall health): 1–70 years of age: 600 IU/day (15 μg equivalent) 71+ years of age: 800 IU/day Recommendations assumes no skin synthesis of vitamin D and refers to total intake from food, beverages and supplements. 26

ABSORPTION, TRANSPORT AND EXCRETION OF VITAMIN D Absorption and Transportation Absorbed via micelles and transported via chylomicrons in the lymphatic system Bound to a protein Synthesis of the active form is regulated by parathyroid hormone and kidneys Excretion Small amount in urine and bile 27

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FUNCTIONS OF VITAMIN D Calcium and Phosphorus Homeostasis Aid in increasing absorption of calcium Aid in releasing calcium from bone, if necessary Bone Health Immune Function (cold and flu) Cancer (breast, colon, prostrate) Heart disease Type 1 diabetes 29

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VITAMIN D DISEASES Deficiencies Children-rickets Adults-osteomalacia Toxicities Does not occur from sunlight or dietary sources Does occur with supplementation Upper limit 4000 IU daily 31

VITAMIN E 8 compounds 4 tocopherols 4 tocotrienols Dietary sources: Plant oils, wheat germ, asparagus, almonds, peanuts and sunflower seeds 32

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VITAMIN E NEEDS RDA 15 mg daily of alpha-tocopherol Daily Value 30 IU (approximately 20 mg) Adults consume approximately 2/3 the RDA 34

ABSORPTION, TRANSPORT AND EXCRETION OF VITAMIN E Absorption and Transportation Micelles into chylomicrons Transported via lipoproteins Stored in adipose tissue Excretion Bile, urine and skin 35

VITAMIN E FUNCTIONS Antioxidant Reduces oxidative stress Other antioxidant compounds Glutathione peroxidase Selenium Superoxide dismutase Copper, Zinc and Manganese 36

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VITAMIN E DISEASES Deficiencies Hemolytic anemia-rare in humans Toxicities Interfere with Vitamin K and cause hemorrhaging Upper limit: 1000 mg natural sources 1100 IU synthetic sources 39

VITAMIN K Menaquinones Synthesized by gut bacteria Fish oils and meats Phylloquinones Plants: green leafy vegetables, broccoli, peas and green beans Most biologically active 40

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VITAMIN K NEEDS AI Women 90 micrograms daily Men 120 micrograms daily Daily Value 80 micrograms 42

ABSORPTION, TRANSPORT AND EXCRETION OF VITAMIN K Absorption and Transportation Absorbed in small intestine, via chylomicrons in lymphatic system. Transported via lipoproteins and stored in the liver Excretion Primarily bile, small amount urine 43

VITAMIN K Functions Blood clotting factors Bone health May protect the body from inflammation Deficiency Rare: long term antibiotic use or fat malabsorption Toxicity No UL 44

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DIETARY SUPPLEMENTS Dietary Supplement Health and Education Act of 1994 (DSHEA) A mineral A vitamin An amino acid A herb, a botanical, or a plant extract A combination of any of the above 46

VITAMIN/MINERAL SUPPLEMENTATION Individuals that may benefit Things to look for: No more than 100% Daily Value USP certification Diet and supplement shouldn’t exceed ULs Check for superfluous ingredients 47