HNF 461 1st Edition Lecture 31 Outline of Last Lecture I Protein Requirements II Protein Turnover III Protein Quality IV Complementary Foods V Evaluation of Protein Quality a AAS b PDCAAS c PER VI Nutrition Fact Labels Outline of Current Lecture 1 Evaluation of Protein Quality Cont 2 Determining Protein Requirement by Nitrogen Balance 3 Types of Nitrogen Balance 4 Body Protein Retention 5 Protein Metabolism a Food Intake b Fasting c Starvation 6 Assessing Diet Protein Requirements 7 Infant Protein Requirement 8 Adult Protein Requirement 9 Direct Amino Acid Oxidation DAAO 10 Indicator Amino Acid IAAO Method 11 Factorial Method for Protein Requirements These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Current Lecture Determining Protein Requirement 1 Evaluation of Protein Quality Cont a Biological Value BV Measure of Nitrogen Retained Nitrogen Absorbed b Net Protein Utilization NPU Measure of Nitrogen Retained Nitrogen Consumed i Does not consider the amount of nitrogen actually absorbed 2 Determining Protein Requirement by Nitrogen Balance a 1 g N 6 25 g protein b Testing subject to determine how much protein is adequate i Adequate protein intake when amount of nitrogen consumed amount of nitrogen excreted nitrogen balance 3 Types of Nitrogen Balance a Positive nitrogen balance intake excretion i Growth ii Pregnancy iii Recovery stage after illness iv Athletic training b Equilibrium intake excretion c Negative nitrogen balance intake excretion i Inadequate protein intake ii Inadequate energy intake iii Illness iv Bed rest v Deficiency of essential AA vi Increased protein loss 4 Body Protein Retention a The body constantly synthesizes new proteins and breaks down old ones turnover rate of proteins is very high b Protein Synthesis g kg day i Infant 4 5 ii Teenager 3 8 iii Young adult 2 5 iv Elderly 2 0 5 Protein Metabolism a Food Intake i After a meal insulin increased decreased catabolic hormones ii Increased protein synthesis iii Decreased protein catabolism b Fasting i Decreased insulin ii Period of negative protein balance iii Increase in protein catabolism to mobilize balance 1 Free amino acids go to liver to synthesize glucose until next meal c Starvation i As glycogen is depleted increased use of AA for gluconeogenesis 1 Early starvation large loss of muscle protein in order to maintain glucose synthesis ii See increase in ketogenesis and lower gluconeogenesis in later starvation 1 Body begins to conserve muscle protein 6 Assessing Diet Protein Requirements a Simplest approach examine diet protein and amino acid content b Second approach measure dose response growth nitrogen balance and AA oxidation c Third approach factorial sum requirements for maintenance growth 7 Infant Protein Requirement a Based on intake of breast milk b AI is 1 52 g kg day for infants up to 6 months 8 Adult Protein Requirement a Based on nitrogen balance b Nitrogen equilibrium is not necessarily amino acid equilibrium 9 Direct Amino Acid Oxidation DAAO a Label carbon on indispensable amino acid b Amino acid requirement is the point at which the graph s slope begins to increase 10 Indicator Amino Acid IAAO Method a Give excess phenylalanine labeled with C13 and tyrosine b Lose C13 because it is used for formation of other amino acids c Requirement is the point at which the graph s slope begins to level out 11 Factorial Method for Protein Requirements a Protein deposition of 43 efficiency 22 g kg day b EAR 66 22 g kg day i Population average c RDA 1 1 g kg day i Greater than EAR value
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