5 Folate

Question 1

Folate aka

Answer 1

Folacin
Folic Acid (supplement / fortified name)

Question 2

Folate named when

Answer 2

Folate in foods or body

Question 3

folate chemical name

Answer 3

pteroylglutamate or pteroylglutamic acid

Question 4

Folate structural features

Answer 4

Pteroic Acid + glutamate

Question 5

C units attach where on folate for coenzyme form? ***

Answer 5

N-5 and N-10 ***

Question 6

Folate activated by what reaction

Answer 6

reduction

- added hydrogens to 5,6,7,8 positions

Question 7

Folate reductions

Answer 7

folate –> dihydrofolate (DHF) –> tetrahydrofolate (THF)

THF fully reduced form

Question 8

What vitamins reduces (adds H) to folate?

Answer 8

Niacin NADH

Question 9

tetrahydrofolate multiple forms formed by? what is the circulating form?

Answer 9

6 different forms made by addition of one carbon units
(must be in THF form to add carbon units)

N5-methyl THF = circulating form

Question 10

Folate circulating form

Answer 10

N5-methyl THF

Question 11

Majority of food folates are

Answer 11

polyglutamates

Question 12

Necessary process to absorb folate

Answer 12

polyglutamates food form

- cleaved to monoglutamate to be absorbed

Question 13

Drugs and folate

Answer 13

inhibit absorption

compete for transport

Question 14

Folate uses what in order to travel

Answer 14

binding proteins

many water soluble proteins use this

Question 15

Folate short term storage in cells by

Answer 15

adding back glutamates (polyglutamate)

Question 16

Folate metabolic role

Answer 16

THF
acceptor of 1 carbon units
1. AA metabolism
2. nucleotide metabolism

Question 17

Folate amino acid metabolism

Answer 17

1. Methionine synthesis (hcy –> met)
2. Histidine catabolism
3. interconversion of serine + glycine

Question 18

Folate deficiency test

Answer 18

role of histidine metabolism

FIGLU

Question 19

Folate Nucleotide metabolism

Answer 19

1. synthesis of purines and pyrimidines (adenine, guanine, uracil, thymine, cytosine)
2. DNA synthesis

Question 20

Methotrexate

Answer 20

chemotherapy drug

slows conversion of DHF to THF

Question 21

Folate food sources

Answer 21

Dark green vegetables
Corn, dried peas, beens, lentils
Fortified in white flour, corn meal, rich pastas

Question 22

Folate deficiency symptoms

Answer 22

Macrocytic anemia (same as B12)

• decreased oxygen carrying capacity of blood
• weekness, depression

*increased homocysteine Hcy

Neural tube defects

Question 23

Folate and b12

Answer 23

Same macrocytic anemia with deficiency

- Increasing folate will correct this but not the neurological effects of b12 deficiency

Question 24

Diagnosing Folate deficiency

Answer 24

Histidine Load test (FIGLU test)

• Give excess histidine, measure FIGLU in urine after 24hrs
• High than folate deficiency

Question 25

Folate vs Folic Acid (supplement form)

Answer 25

Folate LESS bioavailable

approximately 2:1 (on empty stomach)

Question 26

Neural Tube Defects occur? prevented?

Answer 26

21-28 days post conception (before knowledge of pregnancy)

Folic acid supplementation

Question 27

Folate Fortification Debate

Answer 27

important for women becoming pregnant, not so much others

can increase cancer risk

Question 28

Folate and caner

Answer 28

Contribute to genetic stability (lowers colorectal cancer)
- proper function of Wnt cascade

Cancer cells need folate to maintain “tymidine synthesis” at a pace needed to maintain high rate of DNA synthesis
- paradoxical acceleration of carcinogenesis

Core issues (large area of study):

1. timing of exposure
2. level of exposure
3. folate versus folic acid

Question 29

Current interest around folate stems around discovery of ?

Importance?

Answer 29

Single nucleotide polymorphism
- alternations in genes coding for folate dependent enzymes (5,10-methylene THF reductase “MTHFR”)

Increase risk of disease (Neural tube defect and breast cancer)

Question 30

Would B12 fortification help folate def?

Answer 30

Neural tube defects helped with B12
B12 fortification would not solve malabsorption problem

Large area of study. Still unknown

Question 31

Homocysteine an intermediate of

Answer 31

Methionine metabolism

Question 32

Diseases associated with homocysteine

Answer 32

CVD

- possible dementia/alzheimers

Question 33

3 Homocysteine fates?

Needs?

Answer 33

Good:
remethylation to methionine (B12)
Transsulfeation to cysteine (B6)

Bad:
Release to blood

folate, b6 and b12