Vitamin Mineral Zinc Zn Copper Cu Iron Fe RDA UL Men 11 mg d Women 8 mg d Pregnancy 11 mg d Lactation 12 mg d RDA UL Men 0 9 mg d Women 0 9 mg d Pregnancy 1 0 mg d Lactation 1 3 mg d 40 mg d any more produces copper deficiency 10 mg d Food Sources Food Sources RDA Food Sources Organ meats seafood eggs Endogenous sources from pancreatic and biliary secretions carboxypeptidase Organ meats shellfish nuts seeds legumes Endogenous sources from digestive juices Bioavailability Bioavailability Heating causes zinc to form complexes that resist hydrolysis Maillard reactions diminish bioavailablity RDA Men 8 mg d Women 18 mg d Pregnancy 27 mg d Lactation 9 mg d UL 45 mg d Food Sources Heme animal sources Meat poultry fish oysters Non heme plant sources nuts dark leafy greens grains tofu Others Supplements like ferrous sulfate ferric citrate Cooking utensils cooking in cast iron skillet gives your food more iron Bioavailability Available as heme iron in following forms hemoglobin myoglobin animal products such as meat but not dairy will contain 50 60 heme Also available as non heme iron but must be hydrolyzed before can be absorbed Body Content Body Forms Storage Forms Body Content 1 5 2 5 g Body Forms Body Content 50 150 mg Body Forms 2 4 g Body Forms Forms ingested as Zn2 same form in whole body Storage Forms Attached to amino acids Forms in body include valence states like coenzyme form of vitamins Cuprous Cu1 Cupric Cu2 Storage Forms Fe3 or ferric which is used for storage and transport Fe2 or ferrous which is used for heme and enzymes Stored as metallothionein MT1 to MT4 is also a zinc Storage Forms Ferritin primary storage form of iron L form mainly in liver and takes up iron slowly H form chaperone also has radical scavenging properties Stored in metallothionein Thionein is a protein and storage for metals when metals attach it becomes metallothionein high concn Stored on CRIP when concentrations are lower Usually found bound to proteins and amino acids Ctr2 transports copper into vesicles within cytoplasm for temp storage Stored in liver brain kidney these have most Digested as Zn2 attached to proteins In stomach and small intestines protein is broken down via HCL proteases and nucleases degrade protein and free Zn Eaten attached to amino acids Stomach and small intestine break down proteins via pepsin HCl proteolytic enzymes Digestion also exists up to 4500 iron atoms per ferritin In apoferritin in enterocyte for short term storage Liver has 60 of body s iron Hemosiderin may be degradation product of ferritin content may be as high as 50 Ferritin Hemosiderin ratio high with low iron concentration and low with high iron concn iron overload Release requires reduction via riboflavin niacin and vit C to enable diffusion through ferritin pores superoxide can also release iron Heme In stomach and small intestine proteases leaves heme intact while pulling heme out of globin protein Nonheme In stomach HCl pepsin proteases release nonheme iron from foods most nonheme is ferric form In intestine Fe3 is reduced to Fe2 due to the change in pH via ferric cupric duodenal cytochrome b reductase and vitamin C Ferric may complex to form ferric hydroxide which precipitates out and cannot be absorbed Heme Across brush border by heme carrier protein I found mostly in duodenum In mucosal cell heme hydrolyzed by heme oxygenase Nonheme Ferrous absorbed via divalent mineral transporter I found mainly in duodenum and is a H symporter low iron more DMTI Absorption Absorbed in jejunum most likely Has to be carrier facilitated via 1 Zip 4 main carrier deficiency is acrodermatitis enteropathica 2 DMT 2ndary carrier zinc up regulates DMT1 expression but does not transport significant amounts of zinc Low intake levels zip 4 dietary doses better High level intakes paracellular diffusion pass zip 4 altogether pass along between cells Absorbed in duodenum and some in stomach May be bound to more absorbable ligands also have active carrier transport to get into cells as well as simple diffusion high concn hCtr1 copper transporter 1 and DMT reduced by copper reductase first with help from ascorbate Ferric may be solubilized through chelation integrin may help part of paraferritin complex Enhancers Enhancers Enhancers Ligands such as citric acid picolinic acid prostaglandins amino acids tri peptides Pancreatic secretions Amino Acids His Met and Cys Organic Acids Citric lactic acetic malic acid Products of protein digestion Inhibitors Low Zn will lead to an increase in transcription of Zip 4 leading to more absorption of Zn Inhibitors Enhancers Inhibitors of Absorption Phytates like phytic acid once bound the Zn can t leave which inhibits absorption Oxalates forms complex binds Zn can t leave inhibits absorption Polyphenols makes it harder for Zn to be removed from the protein it is first attached to Nutrients folate Fe Ca Other heating and maillard reactions decrease bioavailability of Zn Transport Zip 4 into enterocyte Znt 2 3 4 Within cell ZnT 1 Out of cell ZnT 5 Out of body into GI lumen Albumin main blood protein picks up Zn transports around blood Also transferrin a 2 macroglobulin and immunoglobulin Phytates Phytic acid form metal phytate complex phytate binds 2 molecules of Cu Zn through thionein synthesis stimulation Fe compete for DVMT divalent mineral transporter Mo maybe through complexation and precipitation Ca and P mechanism unknown Vitamin C Reduces cupric to cuprous 2 to 1 makes harder to bind Antacids and H2 blockers Change pH of stomach changes HCl can t degrade proteins to break off Cu from protein Body Status adequate copper inhibits copper absorption Cox17 transport for cytochrome c oxidase synthesis CCS transport for superoxide dismutase synthesis Atox1 transports to P type ATPases for cellular export ATPA transporter to get Cu out of enterocyte and into blood stream defect results in Menke s disease increased enterocyte copper concentration At tissues Store Zn in tissues as metallothionein Cysteine residues will bind minerals like Cu Hg Zn Transported in blood by albumin transcuprein and amino acids Acids ascorbic acid citric lactic Sugars fructose MFP meat fish poultry factor a k a non heme iron is absorbed more efficiently when consumed with a heme food i e eat dark leafy greens with an animal product Body status if we have low stores then there will be an increase in iron receptors on the enterocyte Mucin chelates with ferric iron to facilitate absorption Inhibitors Polyphenols tea and
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