Vit B12 and Folate Flashcards Preview

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Flashcards in Vit B12 and Folate Deck (23):
1

folate occurs where

-naturally occuring in greeen veggies

2

folic acid
-what is it
-where is it found

-synthetic form of folate
-used to fortify foods and as a supplement
-in the US and Canada, cereals and grains are fortified with folic acid

3

what are the biological functions of folate

-nucleotide synthesis and methylation

4

where do the functions of folate and B12 intersect

-in the conversion of methyl THF to THF
-this reaction also converts homocystein to methionine

5

why is it important for women to take folate during the time of conception

-this is associated with a decreased risk of NTD's, spina bifida, and anencephaly
-this provides the rationale for the fortification of grains with folic acid

6

ratio of stores to losses of folate
-what is the consequence of this

-100:1 stores to losses, which means you have a large store and you lose it slowly
-is takes 2-3 months in the setting of poor intake or increased demand to become deficient

7

what scenarios could increase the risk of folate deficiency

-increased demans via pregnancy and lactation

8

deficiencies are rare due to wide distribution in food as well as fortification in grains. However, what groups remain at risk for folate def?

-generalized poor diet due to illness or limited availability
-alcohol abuse due to interference with folate absorption and metabolism
-malabsorptive disorders
-drugs interfering with folate absorption or metabolism such as some anticonvulsants

9

what does folate def rersult in

-macrocytosis and eventual macrocytic anemia
-decreased regeneration of other tissues with a rapid turnover rate such as intestinal epithelium

10

what is the problem with reversinf the hematologic manifestations of B12 def without finding the underlying cause

-delay diagnosis of B12 def
-progression of neurological manifestations

11

UL for folic acid and folate

-there is only one for folic acid because it has been seen to reverse the hematologic affects of B12 def and mask the underlying cause

12

source of B12

animal products
-yeast and microorganisms can also be a source

13

what form of B12 is found in enriched cereals and supplements

-synthetic crystalline

14

B12 has 2 known functions in animals

-as a cofactor in the conversion of homocystein to methionine within the cell cytoplasm
-as a cofactor in the conversion of methylmalonyl CoA to succinyl CoA.

15

what is an indicator of B12 def

-an accumulation of methylmalonic acid (MMA)

16

what does absorption of natural B12 in the ileum require

-digestion from protein binding and eventual binding to intrinsic factor

17

what is an alternative absorption process of B12

-nonsaturable and non-carrier mediated process
-only 1 to 2% of the ingested dose is absorbed this way
-synthetic B12 is absorbed by both processes

18

how long does it take to develop B12 def

-months to years
-we have a large store and it takes a long time to become depleted

19

people at risk for B12 def

-vegans and infants of vegan mothers who rely on breastfeeding
-conditions resulting in diminished secretion of gastric acid and or intrinsic factor
-increased consumption of vitamin B12 in the intestine by bacterial overgrowth or parasites
-impaired ileal absorption due to disease, malabsorption, or surgical resection

20

macrocytic anemia and B12

-this is a manifestation of B12 deficiency
-due to induction of functional folate deficiency

21

manifestation of neuronal death in the posterior and lateral columns

-called combined subacute degeneration
-manifests as diminished position and vibratory sense in the fet with gradual progression to ataxia, spasticity and incontinence

22

neuropsychiatric effects of VB12 def

-mental status
-cognitive and mood alterations

23

clinical manifestations of B12 def

-macrocytic anemia
-neuronal death in the posterior and lateral columns of the spinal cord
-neuropsychiatric affects
-glossitis and diarrhea