B12 Flashcards
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| 5382524965 | Coenzyme forms of B12 | cyanocobalamin --Found in supplements adenosulcobalamin --Major form found in food methylcobalamin --coenzyme form | 0 | |
| 5382558932 | food source of B12 | Adenosyl- & hydroxocobalamin Animal products only Meat, poultry, fish, shellfish, egg, milk, milk products Milk products are a lesser source | 1 | |
| 5382592971 | 1. V-B12 is Attached to _________________ in foods 2. Released from food by ____________________________. 3. Binds to ___________ secreted in mouth and stomach (B12+R complex) ****___________ is secreted in stomach as well but travels alone through SI (small intestine) 4. Complex moves from stomach into _________ 5. R protein is _______________________ in duodenum 6. B12 ____________________ to IF in proximal intestine 7. ________________ travels to ileum and binds to receptors 8. B12 __________ & IF __________ | 1. polypeptides 2. gastric acid & pepsin action 3. R Protein ****intrinsic Factor (IF) 4. small intestine 5. hydrolyzed by proteases 6. released and binds 7. B12-IF complex 8. absorbed -- recycled | 2 | |
| 5382657338 | Storage of B12 and DRI | 2-4 mg can take years to develop deficiency RDI = 2.4 micrograms per day 51+ need consume supplement due to decreased ability to absorb B12 due to low gastric acids/enzymes | 3 | |
| 5382678339 | B12 deficiency can cause | **Pernicious anemia --Loss of intrinsic factor and gastric HCl **Megaloblastic anemia (identical to folate deficiency) --Can be cured by folic acid **Neurological problems (10+ years) --Can not be cured by folic acid, SAM required for methylation reactions, Essential for myelin maintenance and thus neural function **Toxicity --None noted and No benefit from excessive intake | 4 | |
| 5382691224 | Vitamin B12 Deficiency Risk Factors | **Strict vegetarians --Due to absence of animal product in diet **Elevation in levels of homocysteine **Factors related to impaired absorption --Elderly: Achlorhydria, lack of IF. alcoholics: lack of IF secretion , gastric bypass surgery(gastrectomy **Parasitic infections (tape worm) **Ileal resection, celiac, ileitis: impaired absorption | 5 | |
| 5382715818 | Concern for V- B12 deficiency in Erythropoiesis | Main concern is its involvement with the B12-dependent enzyme methionine synthase Inability to convert 5-methyl THF to THF Folate remains "trapped" in 5-methyl THF form (the methyl trap hypothesis) Not enough THF to perform necessary functions in RBC synthesis | 6 |