Exam 2 - Vitamin B9, B12

what is the name of vitamin B9

folate

is folate found in animal or plant products

plant

what is the synthetic form of folate called

folic acid

what form of folate does not require any digestion

folic acid

what % of folic acid is absorbed

100%

what does folate contain in its structure? what is required to remove these during digestion?

glutamic acid residues

folate hydrolase (AKA glutamate carboxypeptidase I conjugate, pteryolpolglutamate hydrolase)

what is needed for the digestion of folate

zinc

what is the coenzyme form of folate

5-methyl tetrahydrofolate (THF)

what is the function of THF

methylation: one carbon metabolism

DNA sythesis

Formation of RBC and WBC

AA metabolism

what aids folate when it is participating in AA metabolism

B6, B12, proteins

a lack of vitamin B12 would have what affect on THF

methyl-folate trap: cannot regenerate THF and folate gets trapped as THF

toxicity of folate can increase the risk of what

cancer

too much folic acid can lead to a deficiency of what? what does this mean?

zinc

zinc is needed to digest folate. Too much folic acid can cause zinc deficiency which leads to folate digestion being inhibited

what are some sources of folate

dark green leafy veggies, mushrooms, liver, legumes, fortified cereals

a folate deficiency will produce what s/s

anemia, birth defects, miscarriage, unstable DNA and inadequate DNA repair

what kind of anemia can a folate deficiency cause

megaloblastic macrocytic anemia

what cells of the SI rely heavily on folate for survival? When there is a folate deficiency, what happens to these cells?

enterocytes, they become shorter and cause malabsorptive diarrhea

what populations are at risk for folate deficiency

alcoholics, women of childbearing age, malabsorptive conditions, MTHFR mutations

what does MTHFR stand for? what does this code for?

methylene THF reductase

enzyme in pathway of production of 5-methy THF

what is name of Vitamin B12

cobalamin

what mineral does B12 contain

cobalt

what is the pseudo form of cobalamin

cyanocobalamin (CN)

what are the active coenzyme forms of cobalamin

5-deoxyadenoylcobalamin

methylcobalamin

the methylcobalamin form of Vitamin B12 functions in ___ reactions important for ____ and production of the AA ____

methylation, myelination, methionine from homocysteine

the 5-deoxyadenosylcobalamin form of Vitamin B12 is important for ___ metabolism and metabolism of ___-chain FA

AA, odd

why is supplementation of Vitamin B12 recommended as patients age

it is difficult to absorb

what are good sources of Vitamin B12

meat, milk, eggs, shellfish

what is the primary way in which Vitamin B12 is absorbed

receptor mediated endocytosis in the ileum

what is another way Vitamin B12 can be absorbed besides the primary way

passive diffusion

what is required to bind to Vitamin B12 in order for it to be absorbed into the ileum

IF from the stomach

what enzyme digests Vitamin B12 into the mono-glutamate form

folate hydroxylase

if you increase the dose of Vitamin B12, what happens to absorption

decreases

what carrier protein is used to transport Vitamin B12

transcobalamin

how much Vitamin B12 can be stored? where is it stored?

3-5 years worth

liver, muscles, pituitary, bone, kidney, brain, spleen, heart

what is the main storage form of Vitamin B12

5-deoxyadenosylcobalamin

what are some conditions which can decrease Vitamin B12 digestion and absorption

zollinger ellison syndrome from too much HCL

medications such as histamine blockers, metformin, protein pump inhibitors

pancreatic insufficiency due to lack of proteases to release B12 from proteins

malabsorptive syndromes

like folate, Vitamin B12 deficiency can lead to megaloblastic macrocytic anemia. What is a major difference between Vitamin B12 deficiency and folate deficiency?

peripheral neuropathy is present in Vitamin B12 deficiency

who is at risk for Vitamin B12 deficiency

vegans/vegetarians

elderly

pernicious anemia (IF autoantibodies)

gastritis

achlorhydria

malab conditions

acid-reducing meds

metformin

zollinger-ellison

is there a Vitamin B12 toxicity

no