Vit B12 and Folate Flashcards
(23 cards)
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
