Vit B12 and Folate Flashcards Preview

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Flashcards in Vit B12 and Folate Deck (23):

folate occurs where

-naturally occuring in greeen veggies


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


what are the biological functions of folate

-nucleotide synthesis and methylation


where do the functions of folate and B12 intersect

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


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


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


what scenarios could increase the risk of folate deficiency

-increased demans via pregnancy and lactation


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


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


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


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


source of B12

animal products
-yeast and microorganisms can also be a source


what form of B12 is found in enriched cereals and supplements

-synthetic crystalline


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.


what is an indicator of B12 def

-an accumulation of methylmalonic acid (MMA)


what does absorption of natural B12 in the ileum require

-digestion from protein binding and eventual binding to intrinsic factor


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


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


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


macrocytic anemia and B12

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


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


neuropsychiatric effects of VB12 def

-mental status
-cognitive and mood alterations


clinical manifestations of B12 def

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