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Updated December 2, 4 - Vitamins - Lecture Notes - LIFESCI 2N03

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Margaret Fahnestock

LECTURE 8LIFESCI 2N03Vitamins December 2 2013History of VitaminsJames LindBritish physician 1716 1794 o Discovered needs of vitamin C in British sailors o Found feeding lime citrus to sailors was beneficialo Vitamin C necessary for collagen synthesiso Scurvydisease caused by vitamin C deficiencySigns and symptomsfatigue anemia low RBC count hemorrhaging teeth loosening softening of bones bending not brittleCasimir FunkPolish biochemist Feb 23 1884Nov 20 1967 o Isolated an amine in ricenitrogen containing functional group o Discoveredproviding an amine improved the healthy of thiamin deprived chickens Thiamin depriveddidnt have any B1o Referred to this amine as vital for life therefore we now have vital amines or vitamins VitaminsVitamins o Organic molecules o Required in small units micrograms quantified in g or mg o Individual unitsnot chains like the macronutrients o Do not contribute to the bodys energy needs in terms of kcalAllows cells to utilize fat carbs and protein but does not provide direct energy o Classificationfat soluble ADEK and water soluble BC o B vitamins tend to be involved in metabolic pathwaysAbsorption o Water solubleVitamin C8 BvitaminsB1 thiamin B2 riboflavin B3 niacin pantothenic acid biotin folate B6 B12Absorbed directly through intestinal cells and into CV systemDissolved in blood so freely transportedSusceptible to kidney filtrationbeyond storage capacity not a large amount of storageNot bound to anything unlike fat soluble small enough to get out of CV system and to be filtered by kidneyTaken in large dosages beyond what is needed by body will be excreted as urine after filtration by kidneyVitamin B12 is stored more than other water soluble vitamins General ruleNeed daily ingestion of watersoluble vitamins not storedEg Vitamin C deficiency symptoms manifest after 2040 daysToxicityrare but possible B most concern ingest at levels above UL 6o Fat soluble Absorbed with dietary lipids packaged into the chylomicronsBioavailability4090 of vitamins consumedEfficiency decreases with greater caloric ingestionNeed lipids to absorb vitaminsPathwayLacteallymphatic system CV systemLipoproteins broken upChylomicron remnants taken up by liver and broken up stores vitamins o Eg beef liverlarge amount of vitamins also cholesterolVitamin B1Thiamin o Part of the coenzyme TPP thiamin pyrophosphateTPP works with PDH pyruvate dehydrogenase enzyme between pyruvate and AcetylcoA if pyruvate binds to PDH it undergoes a one way reaction to become AcetylcoAWhen PDH is active 38 ATP are produced no PDH only 4 ATP made glycolysisIf PDH absentLDHpyruvatelactic acid o RDA11 mgday women 12 mgday men o DeficiencyCaused by a reduction in food intake 1
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