Vit B12 and Folate

Question 1

folate occurs where

Answer 1

-naturally occuring in greeen veggies

Question 2

folic acid

• what is it
• where is it found

Answer 2

• 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

Question 3

what are the biological functions of folate

Answer 3

-nucleotide synthesis and methylation

Question 4

where do the functions of folate and B12 intersect

Answer 4

• in the conversion of methyl THF to THF

- this reaction also converts homocystein to methionine

Question 5

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

Answer 5

• 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

Question 6

ratio of stores to losses of folate

-what is the consequence of this

Answer 6

• 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

Question 7

what scenarios could increase the risk of folate deficiency

Answer 7

-increased demans via pregnancy and lactation

Question 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?

Answer 8

• 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

Question 9

what does folate def rersult in

Answer 9

• macrocytosis and eventual macrocytic anemia

- decreased regeneration of other tissues with a rapid turnover rate such as intestinal epithelium

Question 10

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

Answer 10

• delay diagnosis of B12 def

- progression of neurological manifestations

Question 11

UL for folic acid and folate

Answer 11

-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

Question 12

source of B12

Answer 12

animal products

-yeast and microorganisms can also be a source

Question 13

what form of B12 is found in enriched cereals and supplements

Answer 13

-synthetic crystalline

Question 14

B12 has 2 known functions in animals

Answer 14

• 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.

Question 15

what is an indicator of B12 def

Answer 15

-an accumulation of methylmalonic acid (MMA)

Question 16

what does absorption of natural B12 in the ileum require

Answer 16

-digestion from protein binding and eventual binding to intrinsic factor

Question 17

what is an alternative absorption process of B12

Answer 17

• 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

Question 18

how long does it take to develop B12 def

Answer 18

• months to years

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

Question 19

people at risk for B12 def

Answer 19

• 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

Question 20

macrocytic anemia and B12

Answer 20

• this is a manifestation of B12 deficiency

- due to induction of functional folate deficiency

Question 21

manifestation of neuronal death in the posterior and lateral columns

Answer 21

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

Question 22

neuropsychiatric effects of VB12 def

Answer 22

• mental status

- cognitive and mood alterations

Question 23

clinical manifestations of B12 def

Answer 23

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