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Nutrition 4020 > Vitamin B12 > Flashcards

Vitamin B12 Flashcards

1
Q

What are the names for B12?

A

Cyanocobalamin
Hydroxocobalamin
Nitrocobalamin
Methylcobalamin

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2
Q

What is the active form of B12 called?

A

Methylcobalamin or 5’ deoxyadenosylcobalamin AKA adenosylcobalamin

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3
Q

T or F
Vitamin B12 can take any form of B12 and convert it to the active form

A

True

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4
Q

T or F
Only Methylcobalamin and 5’ deoxyadenosylcobalamin are active as coenzymes in humans

A

True

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5
Q

_____ is the most used form of B12 in supplements due to its high stability, cost effectiveness, and safety to use

A

Cyanocobalamin

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6
Q

What is the RDA for B12 for adults 19-70?

A

2.4 mcg/ d
2.6 for pregnancy
2.8 for lactation

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7
Q

T or F
Some researches indicate the current RDA may not be sufficient for adequate daily intake

A

True

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8
Q

T or F
B12 is the only B vitamin we store in significant amounts

A

True (3-5 years)

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9
Q

What are animal sources of B12?

A

Mollusks, clams, shellfish
Liver
Pork
Crab
Salmon
Beef

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10
Q

What are non-animal food sources of B12?

A

Milk products
Eggs
Mushrooms
Nori
Tempeh
Sauerkraut
Tea leaves
(Plant sources not always consistent source)

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11
Q

T or F
B12 had no toxicity

A

True

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12
Q

What are the highest sources of B12?

A

Shellfish and liver

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13
Q

B12 losses of up to __% can occur through food processing which involves cooking, pasteurization, and exposure to fluorescent light

A

50%

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14
Q

Gastric epithelial cells secrete ___ and ___ which are responsible for the dissociation of B12 form food proteins that enables binding to ___

A

Hydrochloride acid (parietal cells)
Pepsin (chief cells)
R-binder

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15
Q

____ produce the R-protein and binds to B12 after the dissociation from food proteins in the stomach

A

Salivary glands

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16
Q

___ produce intrinsic factor. B12 and R-protein then passed into duodenum where R protein is removed and free B12 binds to ___. This binding is critical for absorption into the ____ and __ is necessary for the absorption

A

Parietal cells
Intrinsic factor
Terminal ileum
Ca

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17
Q

R protein is also known as ___ or ___. B12 binds to these in order to get into the bloodstream

A

Transcobalamin
Haptocorrin (most common transporter)

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18
Q

T or F
Lysosomes break down B12

A

True

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19
Q

Why is SAM or S-adenosylmethionine important?

A

DNA methylation
Creatine
Carnitine
Antioxidants (glutathionine and taurine)
Melatonin

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20
Q

What vitamins regulate homocysteine?

A

Riboflavin (B2)
Pryidoxine (B6)
Folate (B9)
Methylcobalamin (B12)

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21
Q

There are concerns with having high levels of homocysteine because it can cause damage to the ___ lining of blood vessels, can cause ___ damage, ____, and deterioration of ____ material

A

Endothelial
Oxidative
Endothelial dysfunction
Atrial wall elastic material

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22
Q

B12’s other function ________ happens in the citric acid cycle

A

L-methylmalonyl-Coa-mutase

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23
Q

Propionyl CoA arises from the oxidation of what?

A

Methionine
Isoleucine
Threonine
Odd number chain FA

24
Q

Too much ___ and ___ May directly damage the myelin sheath

A

MMA ( methylmalonic acid)
Homocysteine

25
Where is most vitamin B12 stored?
Liver
26
B12 deficiency is mostly developed due to what?
Malabsorption or dietary inadequacy
27
Strict vegans, ____, people with GI disorders such as ___,___, or ___, elderly, ___, or people who take certain medications such as __ or __ are at risk for deficiency
Vegetarians Gastritis Chrons Small intestinal bacterial overgrowth Weight loss surgeries PPI or metformin
28
T or F B12 deficiency happens in stages
True
29
B12 deficiency starts by serum levels diminishing, cell concentration diminishing, and deficiency occurs where ___ decreases and ___ increases, which can lead to megaloblastiv macrocytic anemia or pernicious anemia
RBC decreases Homocysteine increases
30
What are symptoms of a B12 deficiency?
Fatigue Heart palpitations Shortness of breath Loss of concentration Tingling/ numbness (paresthesia)
31
Some neurological problems associated with B12 are clumsiness, ___, ___, and abnormal gait which can all possibly be irreversible
Poor coordination Numbness/ pain in extremities
32
A deficiency of __ and B12 can both lead to megaloblastic anemia. Giving a person deficient in B12 large doses of ___ form supplement or possible fortification can mask the B12 deficiency which can lead to irreversible nerve damage
Folate Folic acid
33
What are some diseases associated with B12?
CVD (homocysteine) Cognitive decline (raised MMA/ homocysteine linked to Alzheimer’s ) Bone health ARMD frailty/ disability
34
Low __ status in the body requires more B12 consumed or supplementation. Low __ intake/ stratus may inhibit B12 absorption
Iron Calcium
35
T or F The US institute of medicine recommends that adults over 65 consume most of their B12 from fortified foods or supplementation
False, over 50 years old
36
T or F Supplements have been demonstrated as effective in the restoration of B12 blood concentration
True
37
T or F Synthetic vitamin B12 needs a protein to be able to be absorbed
False
38
T or F Absorption of B12 from supplements depends on the dose and frequency of the intake
True
39
T or F Using multivitamins can be inefficient and counterproductive for the supplementation of B12
True
40
B12 can be degraded in the presence of __ and __ with the formation of inactive byproducts
Vitamin C Copper
41
T or F There is no clear toxicity from large doses of B12 and no UL has been established
True
42
Which are true about B12 absorption/ digestion? A. Pepsin is made my parietal cells B. Protein must be cleaved off by pepsin and or HCL C. Intrinsic factor bonds to B12 in the stomach D. Two correct E. All correct
B
43
Which are functions of B12? A. Converting of homocysteine into methionine B. Increasing folate absorption C. Regulation of pyridoxal levels D. Two correct E. All correct
A
44
Which if the following are possible deficiency symptoms of B12? A. Bone spurs B. Succinyl CoA toxicity C. Spina bifida D. Two correct E. All correct
C
45
Which if the following are prone to a vitamin B12 deficiency? A. Those with Chrons disease B. Developing countries C. Elderly D. Two correct E. All correct
E
46
T or F Decreased vitamin B12 consumption is recommended when someone is taking a PPI which is a medication used for GERD
False
47
Which if the following are functions of vitamin B12? A. Methionine synthase B. L-methyl-coa-synthase C. Methionine mutase D. Two correct E. All correct
A
48
T or F When vitamin B12 is supplemented in large amounts (1000 mcg) about 1% is absorbed
True
49
Which if the following are true? A. SAH is converted to SAM B. Homocysteine is converted directly to cysteine C. THF and 5-methyl THF are forms of B9 D. Two correct E. All correct
C
50
Which if the following is correct about B12? A. Haptocorrin is made by white blood cells B. The RDA for pregnancy and lactation is the same C. Hydro-aquacobalamin is a form of B12 D. Two correct E. All correct
A
51
T or F A form of folate that is responsible for DNA synthesis is 5-methyl THF
False
52
T or F S-adenosylmethionine (SAM) is a step involved in DNA methylation
True
53
T or F Cobalamin donates a methyl group to 5-methyl THF
False
54
T or F Methionine synthase is important for donating a methyl group to homocysteine
True
55
T or F Methionine is converted to SAH then converted to S-adenosylmethionine (SAM)
False
56
T or F A deficiency of folate and B12 can both lead to anemia. Giving a person deficient in B12 large does of folic acid can mask the problem leading to pernicious anemia, which can cause irreversible nerve damage
False, megaloblastic anemia

Nutrition 4020 (15 decks)

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