B6,B9,B12

Question 1

Folate B9 folic acid

Question 2

folate b9 active form body

Answer 2

tetrahydrofolate THF

Question 3

folate b9 active form food

Answer 3

polyglutamate

Question 4

folate b9 sources

Answer 4

• Yeast, mushrooms, green vegetables, legumes, liver,
  fortified foods, citrus fruits – especially strawberries and
  oranges

Question 5

Folate b9 enzyme that hydolyze it

Answer 5

conjugase

Question 6

Folate b9 conjugase inhibitor

Answer 6

low zinc status, alcohol, inhibitors in foods

Question 7

folate b9 function

Answer 7

• Functions in single carbon transfers in:
• Nucleic Acid Synthesis
• dUMP converted to dTMP (required for DNA
  synthesis)
• Carbon donator in purine synthesis
• Essential for cell division
• Amino Acid Metabolism
• homocysteine converted to methionine
• Glycine converted to serine

Question 8

resynthesis of methionine from homocysteine

Answer 8

• Methionine -> homocysteine
  Too much want to convert back to methionine
  -2 ways: either converting to something else
  (cystathionine) with use of VitB6 or go back
  to methionine w/ methionine synthase
  -Too much homocysteine = risk higher CVD
  -PLP to help homocysteine to cystathionine
  -1 methyl group difference in cystathionine to
  become methionine (methylcobalamine)
  Methylcobalamin (cobalamin is B12) to
  homocysteine
  -cobalamin left when become methionine
• Cobalamin can get methyl group and
  become methylcobalamin from 5-methyl
  THF
  -Becomes THF = active form of folate
• THF becomes 5,10 methylene THF
  -1 way direction, trapped in body
  *All other forms of folate can convert to each
  other as long as it is not in the form of
  5,10 methylene THF
  -THF used for glycine and serine
• Cobalamin B12 saves the trapped form of
  folate in body

Question 9

folate b9 deficiency

Answer 9

Megaloblastic Anemia
* immature red blood cells
* Due to decreased DNA synthesis and improper cell
division along with continued RNA production

Question 10

folate b9 deficiency risk

Answer 10

• Pregnancy
• Birth defects highly
  correlated with folate
  deficiency
• alcoholism
• Elderly
• Phenytoin users
  (anticonvulsant)

Question 11

folate b9 toxicity

Answer 11

• Supplementation may mask
  B12 deficiency while
  permitting neurological
  damage caused by B12
  deficiency
• Megadoses may induce
  seizures in epileptics
• UL: 1 mg/d from
  supplements and fortified
  foods

Question 12

Folate b9 interactions

Answer 12

Vitamin B12: Methyl-
folate trap

• Without B12, methyl group
  in N5 methyl THF cannot be
  removed
• Zinc:
• Folate may decrease zinc
  absorption
• Zinc deficiency may
  decrease folate absorption

Question 13

Folate b9 assesment

Answer 13

• Plasma, serum, or RBC
  folate
• Deoxyuridine suppression
  test (from dUMP to dTMP)
• Plasma homocysteine

concentrations

Question 14

cobalamin b12 sources

Answer 14

nature B12 is made by
microbes (ie. in
rumen and ileum of some
animals), so animal
products are the main
sources (MFP, egg, milk)

Question 15

cobalamin b12 absorption

Answer 15

Mechanisms:
I. Intrinsic Factor mediated absorption
1) Intrinsic factor (IF, a glycoprotein) is synthesized in
the stomach.
2) B12 combines with r-protein stomach and
travels to small intestine
3) B12 releases R protein and complexes with IF
4) B12-IF is absorbed in the ileum
5) B12 is released once complex is in the enterocyte

Question 16

cobalamin b12 function

Answer 16

Converts homocysteine to methionine by transfer of methyl
group from folate to homocysteine

• Converts methylmalonyl CoA to succinyl CoA which can be
  used in energy metabolism
• nucleic acid synthesis -> through
  methionine formation and possibly through reduction of
  ribonucleotides to deoxyribonucleotides

Question 17

cobalamin b12 deficiency

Answer 17

megaloblastic anemia

Question 18

cobalamin b12 deficiency symptoms

Answer 18

• Large immature red blood
  cells, neuropathy, increased
  mean corpuscular volume
  (MCV)
• Usually due to decreased
  absorption secondary to
  lack of IFas opposed to
  decreased intake, called
  pernicious anemia

Question 19

cobalamin b12 at risk groups

Answer 19

• Elderly
• Diseases/Surgery of the
  ileum
• Alcoholic
• Vegans
• Stomach surgery recipients

Question 20

cobalamin b12 toxicity

Answer 20

none

Question 21

cobalamin b12 assessment

Answer 21

• Serum B12
• schilling test
• Used to test B12
  absorption/presence of
  IF
• inc plasma homocysteine

✽ Often done in conjunction
with folate assessment

Question 22

pyridoxine b6 coenzyme

Answer 22

• PL, PM, PN, PLP, PMP, PNP

Question 23

pyridoxine b6 sources

Answer 23

• Liver, nuts, bananas, legumes, meat, whole grains, salmon, sirloin steak, white meat chicken

Question 24

how is pyridoxine b6 metabolised to other forms

Answer 24

by phosphatase to most active form PLP

Question 25

pyridoxine b6 function

Answer 25

1) Amino acid metabolism ▪ Transamination coenzyme (ie. AST/GOT, ALT/GPT) ▪ Decarboxylation (ie. serotonin production) ▪ Transulfhydration/desulfhydration (ie. methionine to cysteine or cysteine to pyruvate) ▪ Cleavage (ie. serine to glycine in folate metabolism) 2) Heme formation- with b6 and iron and makes red color of blood 3) niacin synthesis 4) Arachidonic acid production from lineoleate 5) Glycogenolysis (glycogen phosphorylase)

Question 26

pyridoxine b6 effects

Answer 26

coronary heart disease, premenstrual syndrome, and carpal tunnel syndrome

Question 27

pyridoxine b6 deficiency symptoms

Answer 27

* Lethargy in adult * Seizures in infants * hypochromic/microcytic anemia * Depression

Question 28

pyridoxine b6 at risk groups

Answer 28

* Breastfed infants of mothers with deficiency * Elderly * Alcoholics * Oral contraceptive users

Question 29

pyridoxine b6 assessment

Answer 29

- plansme PLP - trasaminase activity - tryptophan load- b6 is required to convert to niacin

Question 29

B1 B2 B3 B5 B6 B7 B9 B12

Answer 29

Thiamin Riboflavin Niacin Pantothenic Acid Pyridoxine Biotin Folate Cobalamin