11:08:11 - Zinc & Copper

11:08:11 - Zinc & Copper - Zinc Zinc Is found in all...

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Unformatted text preview: Zinc Zinc Is found in all organs and tissues although primarily intracellularlly. Sources: Zinc sources are associated with foods with complex protein structures DRI mg/day 1-3 3 4-8 5 Males 9 – 13 8 14 - >70 11 Females 9 – 13 8 14 – 18 9 19 - > 70 8 • Heating can cause zinc to form complexes that resist hydrolysis. Example: Maillard reaction: amino acid-carbohydrate complex formed in browning. • GI tract will hydrolyze enzymes after use and absorb zinc rather than lose through feces. • proteases, nucleases and HCl •Meds that increase pH of stomach (antacids, beta blockers) will tend to inhibit zinc release from foods. Absorption 10 – 59% absorbed. 1)Carrier mediated – improves with larger intake 2)Passive diffusion Absorption is most efficient in the jejunum but can occur throughout the small intestine. Fig. 12-9, p. 490 Factors enhancing absorption Several substance can act as ligands that aid absorptions: citric acid, prostaglandins, amino acids: histidine, cysteine, pancreatic secretions, products of protein digestion Factors inhibiting zinc absorption Phytate, oxalic acid, polyphenols, minerals: nonheme iron, calcium and copper. Theory: Zn 2+ , Fe 2+ , Ca 2+ , Cu 2+ all compete for binding ligands or for transporters. Zinc and iron tend to interact when coingested. Once in the enterocyte zinc can be: 1) used functionally by the cell 2) stored 3) transported through the cell and across the basolateral membrane into the plasma. Fig. 12-10, p. 490 Transport There are several zinc transporters to move zinc in and out of various cells. Zinc is bound to albumin for transport through the blood to the liver. When leaving the liver, zinc can be bound to albumin (60%) transferrin immunoglobulin α-2 macroglobulin....
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This note was uploaded on 11/25/2011 for the course NTR 365 taught by Professor Sweltzer during the Fall '11 term at University of Texas.

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11:08:11 - Zinc & Copper - Zinc Zinc Is found in all...

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