BIBC120 - Nutri&on BIBC 120 Lecture 5...

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Unformatted text preview: Nutri&on BIBC 120 Lecture 5 Proteins Linda Strause, PhD Office: Muir 2268 lstrause@ucsd.edu Protein Efficiency Ra&o •  •  •  •  •  •  •  • Used by FDA to set standards for baby food • Compares the weight gained in a growing rat aRer 10 days or more ea&ng a standard amount of protein Gram weight gain Gram protein consumed PER =Gram weight gain/Gram protein consumed Chemical Score of Protein • Ra&o of each essen&al AA in a gram of test protein to that essen&al AA in an ideal protein (egg white). • The most limi&ng AA is used for scoring that food •  Chem.Score =mg of EAA (most limi&ng) per gm of protein/mg of EAA per gm of egg white protein Biological Value • Measure protein (AA) reten&on •  BV = Nitrogen retained/Nitrogen absorbed X 100 Protein Diges&on Protein Diges&bility Corrected •  AA Score (PDCAAS) • Most widely used (on food labels) • Maximum value is 1.0 (= milk, eggs, soy protein) •  PDCAAS = Chem. Score x (~0.9 ­1.0) Range of diges&bility Essen&al and Nonessen&al AA Func&ons of Proteins • Building blocks of body components • Maintain fluid balance • Contribute to acid/base balance • Building block for hormones and enzymes • Immune func&on • Gluconeogenesis • Energy yielding High ­Protein Diets ORen associated with: • Low intake of plant foods  ­> reduced fiber and phytonutrients. • High intake of saturated fat from animal ­based foods  ­> increases risk for heart disease. • Excessive intake of red or processed meat  ­> increased risk of colon cancer. • Glycans (carbs) from red meat and milk (mammalian protein not fish or chicken) get incorporated into human glycoproteins and s&mulate inflamma&on leading to increase risk of carcinomas • Extra burden on kidneys to excrete excess urea. Limited Amino Acids Protein Metabolism Protein Metabolism Synthesis of Tyrosine Phenylalanine Tyrosine (Essen&al AA) phenylalanine hydroxyase (Nonessen&al AA) ...
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This note was uploaded on 01/12/2012 for the course BICD 110 taught by Professor Mel during the Spring '06 term at UCSD.

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