UD NTDT 200 - Chapter 11 – Fat Soluble Vitamins

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Chapter 11 – Fat Soluble Vitamins1. Vitamin Aa. Precursor – beta- caroteneb. Forms: Retinol (supports reproduction, major transport and storage form), retinal (active in vision), retinoic acid (regulated cell differentiation, growth, and embryonic development)c. Carotenoids- come from plaints and convert to Vitamin A. less effective than retinoidse. Storage – absorbed via lymph and carried to livef. Major roles in Bodyi. Vision1. Cornea2. Retinaa. Photosensitive cellsb. Rhodopsin- pigment molecules3. Repeated small loses of retinala. Need for replenishment – need more Ai. taking more from the liver to replenish what’s lostii. cause of blindnessii. Protein synthesis and cell differentiationiii. Reproduction and growth1. Reproduction and growtha. Sperm developmentb. Normal fetal development in pregnancyc. Growth of childrend. Bone growth2. Antioxidanta. Beta-carotene- not all is converted to A, some acts as an antioxidantv. Digestion and absorption of vitamin A: aided by proteinsvi. Storage: absorbed via lymph and carried to livervii. Transport protein: Retinol-binding protein (RBP) goes through bloodix. Goblet cells- cells that make mucusa. Without Vit A, you do not have healthy mucus membraneh. Deficiencyi. Vitamin A status depends ona. Adequacy of stores- 90% store in liverb. Protein status- protein needed for transport of Vit of Aii. Consequences of deficiency- appear after 1-2 years (adults), sooner for kidsa. Risk of infectious diseasesi.Measles- causes worse with inadequate Aii.Malaria, lung disease, and HIVb. Blindnessi. Night blindness- Inadequate supply of retinal to retinaii. Total blindness (xerophthalmia)- lack of Vit A at corneac. Deathiii. Keratinizationa. Keratin is hard protein on hair, nailsi. Change in shape & size of epithelial cellsii. Skin becomes dry, rough, and scalyiii. Normal digestion and absorption of nutrients from GI tract faltersi. Weakened defenses in respiratory tract, vagina, inner ear, and urinary tract- Everything stops workingi. Toxicity of Vitamin A and Beta-Carotenei. Develops when binding proteins are loadeda. Free vitamin A (not bound) damages cellsii. Toxicity is a real possibilitya. Preformed Vitamin A (not something that has to be converted in the body) from animal sources, fortified foods (supplements of vitamin A or fortified foods with it), or supplementsiii. Children are most vulnerablea. They have little bodies and need lessj. Vitamin A and Beta- Carotene Toxicityi. Beta-carotenea. Found in many fruits and vegetablesb. Overconsumption from food causes yellow skinc. Overconsumption from supplements1. Antioxident becomes prooxident2. Adverse affects seen in drinkers and smokers3. Prooxident - induuces oxidative stressii. Bone defectsa. May weaken bones1. Osteoporosis2. Interferes with vitamin D ability to maintain calcium levelsiii. Birth defects- considered a teratogena. Cell death in the spinal cordiv. Acne- Retin A is relatedv. Gene expressionk. Food sourcesi. Animal sourcesa. Liver and toxicity concernsii. Plant sourcesa. Vitamin A precursors- beta-carotene (veg); retinoids (liver, fish oil, butter, eggs). Skim milk fortified – A bound with fatb. Colors of food- leafy greens/orange, yellow foods, liver2. Vitamin Da. Not an essential nutrienti. Body synthesizes (body can make it, so it’s not essential)1. Sunlight2. Precursor from cholesterolb. Activation of vitamin Di. Two hydroxylation reactions occur in:1. Liver2. Kidneyc. Vitamin D – Roles in the Bodyi. Active form of vitamin D is a hormone1. Binding protein carries it to target organsii. Bone growth1. Enhances calcium and phosphorus absorption2. Helps bones absorb nutrients from the GI tractiii. Other roles-1. Enhances or suppresses gene activityd. Vitamin D – Deficiencyi. Overt signs are relatively rare Insufficiency is quite commonii. Contributory factorsa. Dark skin, breastfeeding without supplementation, lack of sunlight, not using fortified milkiii. Creates a calcium deficiency - Biggest sign- bone fracturesiv. Ricketsa. Bones fail to calcify normally; Bones bend, beading on the ribsb. Affects childrenv. Osteomalaciaa. Poor mineralization of bones, affects adultsb. Bones are soft (more likely to brake), flexible, brittle, and deformed (bones are spongy, big holes)vi. Osteoporosisa. Loss of calcium from bones Results in fracturesb. Elderly at risk1. Vitamin D deficiency is especially likely2. Lose ability to make and activate Vit D3. Drink less milk4. Spend much of day indoorse. Vitamin D – Recommendation & Sourcesi. Few food sources1. Oily fish and egg yolks2. Fortified milk3. fortified portabella mushroomsii. Recommendations may be insufficient1. Recommendations are difficult to meetiii. Sun exposure1. No risk of toxicity2. Skin color, latitude, season (where the sun is), time of day3. Sunscreen3. Vitamin Ea. Vitamin Ei. Four different tocopherol compounds1. Alpha, beta, gamma, and deltai. Position of methyl group2. Alpha-tocopherol - vitamin E activity in the bodyii. Antioxidant1. Stop chain reaction of free radicalsi. Protect cells and their membranesii. Heart disease and protection of LDLsb. Vitamin E – Deficiency1. Primary deficiency is rare2. Secondary deficiency- fat malabsorption3. Effects of deficiencyi. Red blood cells break openii. Erythrocyte hemolysisc. Vitamin E – Toxicity1. Liver regulates vitamin E concentrations2. Toxicity is rare3. UL is 65 times greater than recommended intake for adults4. Extremely high doses of vitamin Ei. May interfere with vitamin K activitya. Hemorrhage (bleeding)d. Vitamin E – Recommendations & Foods1. RDA is based on alpha-tocopherol only2. U.S. intakes tend to fall short of recommendationsi. Requirements for smokers3. Widespread in foodsi. Destroyed by heat processing and oxidation4. Highest source = wheat germ oil4. Vitamin Ka. Vitamin K1. Can be obtained from non-food sourcei. Bacteria in the GI tract2. Acts primarily in blood clottingii. Prothrombin3. Metabolism of bone proteinsiii. Osteocalcin- Low bone density4. Other possible roles of vitamin K in the bodyb. Vitamin K – Deficiency1. Primary deficiency is rare2. Secondary deficiencyi. Fat absorption faltersii. Some drugs distrupt Vitamin K’s synthesis and actionCoumadin3. Newborn infantsi. Sterile intestinal tract = can’t synthesize Vitamin K1. Single dose of Vitamin K is given to newborns at birth so their blood can clotc. Vitamin K – Toxicity1. Not commoni. No adverse effects with high intakes2. No UL3. High doses can reduce


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UD NTDT 200 - Chapter 11 – Fat Soluble Vitamins

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