Metabolism 2 Study guide Exam 1 By Tony Berardi 1 Explain the DRI The goal of the DRI is to prevent chronic diseases not to prevent defiencys The focus is now on malnutrition from over nutrition DRI started in 1835 with lemons on ships Then first RDA was in 1949 with the focus to prevent defiency in the military Changed because it was too broad focus on healthy people and too many fat unhealthy people Now have EAR RDA AI and UP 2 What are vitamins and difference between fat and water soluble They are micronutrients that must be supplied from the diet Needed for normal function and their absence cause certain symptoms with each one The body can make some but not in appreciable amounts Fat soluble is obviously soluble in fat stored in the body in large amounts so it s not required every day Since it s stored defiency takes a long time to occur Most have precursors and only higher organisms need them Can be toxic at low amounts but still way higher than the UL Water soluble are stored minimally excreted in the urine so defiency can happen much faster Absorbed into blood since water soluble and both simple and complex organisms need Since they aren t really stored they are only toxic at mega doses 100x DRI Thiamin 1 What is the active form of this vitamin Only active as Thiamin pyrophosphate which is also known as Thiamin di and triphosphate So TPP also TDP and TTP Need a phosphate to be active 2 What are the source It s in most foods Liver and yeast are the richest sources followed by meats and whole grains Polished rice is a terrible source There is an enzyme Thiaminase present in raw fish and caffeine that destroy thiamin It is stable in cooking 3 How is it absorbed It has to be in its free Thiamin to be absorbed In the blood it travels as a monophosphated form and bound to albumin Everything vitamin from now on is absorbed by active transport at low concentrations and passive diffusion at high 4 What are its functions It is involved in the krebb cycle mainly by decarboxylating pyruvate to Acetyl CoA Also alpa ketoglutarate to Succinly CoA and the decarboylation of the branch chain amino acids Also in the synthesis of the pentases and NAPH which are involved in making nucleic acids So DNA synthesis In nerve function too but mechanism is not clear 5 What is the defiency and the risk groups Those at risk are the elderly alcoholics and people who eat strictly raw fish Defiency is BeriBeri and there are 4 types Easy to remember cause really only two one affects the cardiovascular and the other is the nervous system So have wet beriberi which is the cardiovascular then dry beriberi which are the nerves Severe is called Wernike s Korakoff and it happens in chronic alcoholics There are two possible symptoms to this Korsakoff phsycosis and Wernickes encephalopathy It can cause death if untreated The DRI is 1 2 mg daily Riboflavin 1 What is the active form Active as Flavin mononucleotide and Flavin Adenine Diphosphate So FMN and FAD Mostly in dairy and milk products grains and meats It is also stable in cooking and is light sensitive 2 What are the sources 3 How is it absorbed Kind of a back and forth thing Must be free flavin to absorb so the HCL cleaves out the proteins it s then phosphylated to FMN in the mucosa then travels to the serosa surface and is dephosphylated back to flavin travels to the liver and phophylated again to FAD Stored in the liver 4 What are the functions FAD so it s in glycolysis as an electron transporter Also in the reduction on glutationin to G5S reduced form 5 What is the defiency The risk groups are elderly alcoholics People with increased needs like pregnant and lactating and trauma patients Babies with hyperbilurbiemia on photo therapy I guess the therapy destroys it Defiency cause oral lesions glossititis and stomatitis 6 How to assess it and what is the DRI To check the values look at the activity of the RBC glutathionin reductase Since need FAD to reduce it and NADPH is a reactant meaning if no FAD then the NAPH won t be used And the NAPH is easy to measure Niacin 1 What is the active form Active as nicatinamide and nicotinic acid 2 What are the sources Meats and fish are the best source since they have free nicotinamide Corn suck dick as a source because it s low in tryptophan But treating the corn with limewater can release the niacin in it The liver can also make it with 60mg of tryptophan 3 What are the functions About 200 reactions but mainly as NAD NADH NAP NAPH NAD is the electron carrier in glycolysis NADH is the molecule when its reduced NAP is involved In the hexose shunt nucleic acids NAPH is involved in many pathways beta oxidation cholesterol synthesis Also can be used to lower cholesterol but side effect is painful Niacin flush caused by release of histadine 4 What is the defiency The risk groups are the people with the higher needs Some drugs can interfere with absorbtion such as Izonaid for tuberculosis There also is a genetic disease where the patient can t metabolize tryptophan Hartnup disease Its autosomal recessive Defiency is Pellagra It s the 4 D s Dermatitis Diarrhea Dementia and Death 5 What is the DRI It is 14 NE or niacin equivalents 1 NE is equal to either 1mg niacin 60mg tryptophan and 6000mg protein Folic Acid 1 What is the synthesis and shit It s made from 9 different precursors such as PABA glutamic acide Pterdine The body can make all except Pterdine acid 2 How is it absorbed It must be absorbed as a monoglutamate form so the polyglutamate is hydrolyzed with a conjugase The conjugase is also Zinc dependent so you need Zinc to absorb Folic acid Some foods have conjugase inhibitors though like oranges cabbage lentin Then it is reduced in the liver to its active form THF Minimal storage of 11 28 mg 3 What are the functions It is use in one carbon transfers in the synthesis of the purines and pyridimes Nucleic acids and in some AA metabolism such as the glycine serin but the important one is the methionine regeneration Green leafy veggies oranges yeast It is destroyed with cooking 50 95 4 What are the sources 5 What is the defiency The risk groups are those that prolonging the cooking Alcoholics pregnant and lactating women are also at risk And some intestinal diseases such as Celiac disease Some drugs also interfere with the absorption such as methotrexate in chemo some antimicrobials and Dilantin an anticonvulsant The defiency causes megaloblastic RBC large and immature 6 How to assess and what is the DRI There are 2 ways
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