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AU - NTRI 2000 - Study Guide - Midterm

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AU - NTRI 2000 - Study Guide - Midterm

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background image Nutrition Class Notes 3/27/18 Chapter 8: Vitamins Introduction to Vitamins: Organic (Carbon-containing) substances needed in small 
amounts in diet
o Promote normal function, growth, maintenance  Each vitamin has an essential function in the body o Functions of vitamins Energy Metabolism Immunity Bone Health Blood Health Antioxidant Systems  Produce deficiency symptoms when missing from diet  Yield no energy (0 kcal) Basic functions o Facilitate energy-yielding chemical reactions
o Function as co-enzymes 
Two Types: o Fat soluble vitamins – A, D, E, K
o Water-soluble vitamins – B’s, & C
To be classified as a vitamin: o Body is unable to synthesize enough of the  compound to maintain health o Absence from diet produces deficiency symptoms  that can be reversed if vitamin is reintroduced  Vitamin Synthesis o Some vitamins CAN be synthesized within the body A – from pigments in plants D – from sunlight exposure Niacin – from AA tryptophan K & Biotin – from bacteria in gut  History Vitamins: o Alphabetic order of discovery 
o Deficiencies linked to specific conditions 
o Megadoses
Proven useful in treating certain conditions  o Most synthetic vitamins work equally well in the body Exceptions – Vitamin E & Folic acid  Absorption & Storage of Fat-Soluble Vitamins Vitamins A, D, E, K  fat soluble Absorbed along with fat
background image o Travel through blood as part of chylomicrons
o Fat malabsorption may cause deficiency 
Stored mainly in liver o Excess intake can cause accumulate  Not readily excreted (except vitamin K) o Possible toxicity if ingested in excess  Absorption & Storage of Water-Soluble Vitamins B’s are broken down from co-enzyme form in stomach/SI 
then absorbed in SI; resynthesized to co-enzyme form in 
cells 
Generally lost from the body (exceptions: vitamins B-6 and 
B-12), so little storage
o Excrete via urine
o Tissue storage is limited so excretion rates can 
increase (such as during increased intake) Vitamin Toxicity: Because vitamins are needed in small amounts, excess can
result in toxicity
o Fat-soluble vitamins Can accumulate in the body Vitamin A is most common toxicity o Water-soluble vitamins Some can cause toxicity; rare o Toxicity is most likely due to supplementation and not from dietary intake  Preservation of Vitamins: Vitamin content of food can be decreased via: o Improper storage 
o Excessive cooking
o Exposure to light, heat, air, water, and alkalinity
Vitamin A: Stored in liver (90%), adipose kidney Two forms: o Preformed Vitamin A – Retinoid Retinol, retinal, retinoic acid Found in animal products o Proformed Vitamin A – Carotenoids Precursors of Vit A with antioxidant properties Beta-carotene Found in plant products  Functions of Vit. A o Important roles of Vitamin A: Health of Epithelial Cells and Immune Function Promotes normal vision
background image Decreases night blindness & macular 
degeneration
CVD Prevention Growth, Development, Reproduction Synthesis, differentiation, maturation of 
cells/proteins
Cancer prevention? Deficiency o Xeropthalmia – “dry eye” Progression of stages from milder night 
blindness to sever kerotomalacia 
o Leading cause of blindness worldwide  Toxicity o Large intake of PREFORMED vitamin A Birth defects & liver toxicity  o High intake during pregnancy: Fetal malformations & spontaneous abortion o No toxic effect of high carotenoid consumption Yellowing of skin  Class Notes 4/3/2018 Thiamin (Vitamin B-1) Coenzyme form used in energy (carbohydrate) 
metabolism
o Thiamin pyrophosphate (TPP) Deficiency: Beriberi o “I cant, I cant”
o Symptoms
Weakness, loss of appetite, irritability, poor 
extremity coordination, muscle pain
o From excess consumption of polished rice &  alcohol abuse  RDA o 1.1 mg/day for women; 1.2 mg/day for men
o Most exceed RDA in diet 
o Excess is rapidly excreted in urine; non-toxic 
Food sources: o Whole grains, ready-to-eat breakfast cereals Riboflavin (Vitamin B-2) Functions: o Coenzyme forms participate in energy-yielding  metabolic pathways these coenzyme forms carry
electrons 
Flavin adenine dinucleotide (FAD)
background image Flavin mononucleotide (FMN) o Indirect antioxidant properties Glutathione peroxidase (GPX) o Homocysteine and some vitamin and mineral  metabolism  Deficiency: ariboflavinosis o Cheilosis (cracking around the mouth, lips, and  tongue), sensitivity to sun RDA o 1.1 mg/day for women; 1.3 mg/day for men
o Average intake above RDA
Found in milk, milk products, enriched 
grains/cereal, liver
Niacin (Vitamin B-3) Coenzyme forms used in energy metabolism these 
coenzyme forms carry electrons
o Nicotinamide adenine dinucleotide (NAD)
o Nicotinamide adenine dinucleotide phosphate 
(NAPD) Niacin can be synthesized from the AA tryptophan  o 60 mg tryp = 1 mg niacin  Deficiency: o Pellagra Consequences Early o Poor appetite, weight loss,  weakness Late (4 D’s) o Dementia, dermatitis, diarrhea
o Death
At risk: Alcoholics Genetic disorder of tryptophan 
metabolism 
Food sources Enriched grains & cereals, Beef, 
Chicken/Turkey
Toxicity High dose niacin (>100 mg, such as in
supplements) can cause headache, 
itching, and flushing of the skin
o Blood vessel dilation resulting in increased blood flow 

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School: Auburn University
Department: Nutrition and Food Sciences
Course: Nutrition and Health
Professor: Ramesh Jeganathan
Term: Summer 2015
Tags:
Name: Nutrition Study Guide for Exam 2
Description: This is the Study Guide for Exam 2
Uploaded: 04/13/2018
16 Pages 49 Views 39 Unlocks
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