B12 & Folate Flashcards

1
Q

Vitamin B12 refers to a family of what

A

cobalamin compounds containing cobalt in the centre

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2
Q

B12 i found only in foods of what origin?

A

animal origin

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3
Q

5 food sources B12

A

meat (esp organ)
fish
eggs
milk & cheese

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4
Q

which food sources do vegans think contain enough vitamin B12 to meet their needs?

A

algea (spirulina)

miso etc

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5
Q

why are plant sources of vitamin B12 no use to us?

A

B12 in those products occurs mainly as inactive analogs and are not utilised by humans

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6
Q

what should all vegans supplement with

A

B12 - or fortified foods with active analogs

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7
Q

how is B12 affected by cooking?

A

as bound to protein, 70% activity is retained

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8
Q

how can B12 be lost in milk

A

when pasteurised or evaporated

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9
Q

as B12 bound to protein it is released by what digestion

A

pepsin digestion in stomach

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10
Q

which is the specific B12 binding protein produced in the stomach

A

Instrinsic factor

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11
Q

where is IF-vit B12 complex absorbed

A

small intestine

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12
Q

where is it B12 stored

A

mainly in liver

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13
Q

which type of circulation contributes to B12 stores in the liver

A

enterohepatic circulation

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14
Q

which 2 processes in the body does B12 facilitate

A

metabolism of folic acid

synthesis of DNA

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15
Q

B12 function in which 2 enzyme forms

A

adenosylcobalamin

methylcobalamin

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16
Q

adenosylcobaliamin & methylcobalamin play an essential role in the metabolsim of

A

all cells

especially GI tract, bone marrow, nervous tissue

17
Q

hyperhomocysteinaemia is what

A

high serum concentrations of homocysteine

18
Q

high serum levels of homocysteine lead to what

A

cardiovascular events

19
Q

taking what can reduce hyperhomocysteinaemia

A

B12, B9 & B6

20
Q

what else does a patient with hyperhomocysteinaemia need to do, besides supplementation, in order to reduce the risk of cardiovascular events

A

lifestyle change

21
Q

who else should supplement with B12

A

Elderly adults - 25-37.5 mcg/day

vegans 1-25mcg/day

22
Q

which other conditions have increased B12requirements

A

pregnancy
thyrotoxosis
malignancy
liver & kidney disease