Folate (Folic Acid)

Question 1

food folate structure

Answer 1

• reduced

- polyglutamated

Question 2

folic acid structure

Answer 2

• oxidized

- monoglutamated

Question 3

folate digestion

Answer 3

-must be hydorlyzed to monoglutamate (folic acid) form first

Question 4

factors affecting folate digestion

Answer 4

• zinc deficiency
• chronic alcohol ingestion
• conjugase inhibitors (decrease digestion)
• -lentils and cabbage
• heat and pH sensitive

Question 5

folate absorption

Answer 5

• inside intestinal cell
• folic acid reduced to THF
• -dihydrofolate reductase
• -4 additional H+ added at 5-8 = 5-methyl THF

Question 6

folate food sources

Answer 6

• green leafy vegetables
• orange juice
• strawberries
• legumes
• fortified food since 1998

Question 7

bioavailability of folate

Answer 7

• food folate= 50%

- folic acid= 85% (1.7x available)=used as fotificant

Question 8

functions of folate

Answer 8

1. conversion of homocysteine to methionine

2. import for DNA synthesis and making new cells

Question 9

disease risk associated with folate

Answer 9

• neural tube defect
• CVD
• megaloblastic anemia

Question 10

neural tube defect (NTD)

Answer 10

• neural tube fails within first 23 days
• effects 1/1000 births
• intake of >400 mg/d= decreased risk by 75%

2 types:

1. anencephaly-absence of cerebral hemisphere
2. spina bifida- defective closure of vertebral column

Question 11

CVD

Answer 11

• defect in breaking down cysteine (accumulates in blood to cause heart problems)
• Hcy increase= 20% increase in risk
• mechanism:
• increase LDL oxidation
• increase thrombosis(increasing in blood clotting)
• toxic effect on endothelial cells

Question 12

megaloblastic anemia

Answer 12

• detected by kidney size
• decreased DNA synthesis
• cells in bone marrow fail to divide
• large and immature RBCs

*also occurs in B12 deficiency

Question 13

folates relationship with B12

Answer 13

• methly trap hypothesis:
• -methyl accumulation
• -THF is not regenerated
• -Thymidine synthesis decrease
• -RBC decrease their ability to carry O2

Mthionine-CH3
to
SAM
to
SAH
to 
Hcyst
to-B6
cysteine

Question 14

folate RDA

Answer 14

-400ug/d for adults of child bearing age
-1 DFE=1 ug food folate
=0.6 ug fortified with food
=0.5 ug supplement on empty stomach

Question 15

folate enrichment

Answer 15

• 140 ug of folc acid per 100 grams of flour
• 200 ug folic acid per day for average diet
• NTD dropped by 25%

Question 16

population at risk of folate deficiency

Answer 16

• elderly
• alcoholics
• achlorhydria
• inflammatory bowel disease
• inalignancies
• pregnant or lactating
• medications:
• -phenytoin, choestryamty, sulfasalazine

Question 17

folate toxicity

Answer 17

• UL=1000 ug/d
• B12 mask:
• -deficiency masked by folic acid
• -feed cancers-5FU drug that inhibits DNA Synthesis
• —enzyme= mesothrexate
• -delays diagnosis by correcting anemia

Question 18

folate nutrition assessment

Answer 18

• FIGLU excretion
• Histine load test=5-20mg is normal
• -not reliable because a lot of variation