folate

Question 1

folate is the “Factor” present in yeast and liver that cured what in who

Answer 1

anaemia in pregnant women

Question 2

folate is isolated from what and names after what

Answer 2

Isolated from spinach and named after the Latin for foliage (folia)

Question 3

folate is a group of chemically related what, with related what

Answer 3

chemically-related vitamers with related activities (pteroylglutamic acid)

Question 4

what does folates structure comprise of

Answer 4

a pteridine ring coupled to para-aminobenzoic acid (pABA)

Question 5

how do vitamers differ

Answer 5

they differ in the oxidation state of the aromatic ring, the type of 1-C units at N5 and N10 and variable number of glutamic acids attached to the pABA

Question 6

what cycle is folate key to

Answer 6

folate cycle

Question 7

whats the importance of folate in the folate cycle

Answer 7

Donates methyl groups to homocystine to make methionine

So need folate to allow normal nucleic acid function

Question 8

folates One Carbon [1-C (methyl)] transfer & methionine metabolism, are substrates and coenzymes for what

Answer 8

for 1-C reactions (e.g. important for DNA and protein synthesis)

Question 9

what is folate function key to

Answer 9

methionine synthesis, via homocysteine (tHcy) metabolism, related to that is the production of S-adenosylmethionine (SAM)

DNA synthesis (2x purines and pyrimidine); key converiosns its involved with is the conversion of dUTP to dTMP

DNA methylation, gene and protein expression

choline synthesis (lipid metabolism, membranes and synthesisng neurotransmitters)

formate catabolism to CO2 and elimination (toxicity) – do detoxifies formate

conversion of serine to glycine (both of those are required for protein synthesis)

One Carbon [1-C (methyl)] transfer & methionine metabolism
These are Substrates and coenzymes for 1-C reactions (e.g. important for DNA and protein synthesis)

Question 10

what percentage of population is clinically folate deficient

Answer 10

10%

Question 11

what percentage of 15-18 year olds have marginal folate status

Answer 11

40%

Question 12

what % of women do not achieve RDA (RNI) even accounting for supplement use

Answer 12

84-92%

Question 13

folate deficiency is common in what age group

Answer 13

> 65y especially institutionalised elderly – eg in care home environment

Question 14

explain pregnancy and neural tube defects(NTD) in terms of folate

Answer 14

600mg/day recommended for women who could become pregnant

84-92% women do not achieve this even with supplements (50% pregnancies unplanned)

high dose folic acid reduces risk of second NTD birth by 50-75%

Question 15

explain the link between vascular disease and folate

Answer 15

high folate intake associated with 35% reduced risk of CVD – cardio vascular disease (reduced levels of homocysteine)

Question 16

explain the link between folate and cancer

Answer 16

poor folate status increases risk of cancer of cervix, lung, pancreas, breast and colon (25%) [note suggested detrimental effect of high doses of folic acid (used in supplements)causing colorectal cancer]

Question 17

explain the link between folate and dementia and cognitive impairment

Answer 17

low folate (and B12; note ‘folate trap’) associated with depression, dementia and poor cognition commonly seen in elderly

Question 18

what does tetrahydro refer to in folate structure

Answer 18

refers to the hydrogen atoms it has. What changes is the group its carrying

Question 19

what are methylene groups structure written as

Answer 19

CH2

Question 20

what are methane group structure written as

Answer 20

CH3

Question 21

in folate what form is used in fortification and supplementation and why

Answer 21

acid form not folate form

Folate form isn’t suitable for supplements as doesn’t survive long whereas folic acid does

Question 22

Folates present in foods as what

Answer 22

polyglutamates (50-75% of what consume
has folate in polyglutamate form)

Question 23

what are the 4 predominant naturally occurring folates in food

Answer 23

THF, DHF, formyl- and methyl

THF – tetra hydro folate
DHF – dihydrofolate

Question 24

5-methyl THF comprises most of the folate in what

Answer 24

in foodstuffs and
circulating form in plasma

Question 25

what are the richest natural sources of folate

Answer 25

green leafy vegetables (spinach, broccoli, B.sprouts) liver, yeast, whole wheat, nuts, beans wholegrain cereals, vegetables and beverages (fruit juices & milk) main contributors in UK Brassicas and green leafy veg are good sources of folate Animal products are less rich in folates compared to plant products Microbes like yeast can synthesis folates. So yeast based products contain folate

Question 26

what percentage of our folate daily intake is from veg excluding potatoes

Answer 26

15%

Question 27

what percentage of of food folates bioavailable

Answer 27

20-50%

Question 28

is folate or folic acid more bioavailable

Answer 28

synthetic folic acid is more bioavailable

Question 29

what folate is in milk

Answer 29

Monoglutamates in milk (easily absorbed)

Question 30

explain food folates that are oxidisable

Answer 30

accurate measurement difficult (tri-enzyme; extracted & hydrolysed to monoglutamates) underestimation in food composition tables Destroyed by heating (boiling v microwave) Unstable during long-term storage Oxidised (stable) folic acid (fortified foods and dietary supplements)

Question 31

what vitamin is folate and what propertys does it have

Answer 31

is water-soluble and a B vitamin and has same problems as them such as that its destroyed by heat, so microwave rather than boil. It also leaches out of substances. Unstable due to sensitivity to oxygen so why folate isn’t used in supplements etc

Question 32

whys liver a good folate source

Answer 32

as it stores folate

Question 33

folates total body pool=

Answer 33

approx. 7.5 mg (but can be as high as 30 mg depending on diet)

Question 34

Depletion studies suggest absolute requirement of what

Answer 34

80-100 µg/day

Question 35

RNI set at what in men and women

Answer 35

200 µg/day

Question 36

explain how much additional intake is required for women planning pregnancy and why and concerns over this

Answer 36

additional 400 µg/day for women planning a pregnancy (prevention of NTDs) is unachievable by diet alone (liver concentrated source; vitamin A teratogenic) Supplements recommended during first trimester as the neural tube defect would coccur within the first 6 weeks before they know theyre pregnant, but 50% pregnancies unplanned – basis of recommendation for mandatory fortification Pregnant women are expected to have supplements cos folate recommendation is so high But pregnant women should avoid liver as a source as contains too much vit A as is dangerous to baby development

Question 37

what is the Mean intake of folate in UK

Answer 37

220-330 µg/day people have currently is 251 µg/day (women) and 344 µg/day (men)]

Question 38

explain link between folate and cancer

Answer 38

Cancerous tissues like folate rich environments so is why we cant fortify all foods with folate Folic acid don’t cause cancer but helps it grow if you do as the tumour can grow faster

Question 39

explain folate absorption and metabolism

Answer 39

folate polyglutamates cleaved to monoglutamate by brush border Zn-dependent peptidase deconjugase (takes polyglutimates off) in duodenum & jejunum (approx. 50% of food folate absorbed 85-100% oxidised folic acid) then , alcohol deconjugase inhibitors in diet then methylated in intestinal mucosa & transported to liver in blood and bound to albumin in portal circulation reduced to DHF and then THF by DHFR in the liver then re-polyglutamated (polyglutimates reattached) & stored in liver (6-20mg stores; 2-7 months) or transported to other tissues

Question 40

in absorption which of the 2 (Polyglutimates and Monoglutimates) can be absorbed

Answer 40

monoglutimates

Question 41

explain folates interaction with alcohol

Answer 41

Alcohol is key thing that interferes with folate absorption deficiency common in alcoholics (60-70% binge drinkers are folate deficient) intervention with alcohol (24g/day /2 weeks) decreases blood folate by approx.10% alcohol causes folate malabsorption downsteam effect on key methyl donors (e.g. SAM)

Question 42

what cells are vulnerable to folate deficiency

Answer 42

rapid dividing cells as (requirement for DNA synthesis)

Question 43

for a clinical deficiency how much folate is there in plasma and RBC - red blood cells

Answer 43

<2-3ng/ml in plasma and 100ng/ml in RBC

Question 44

what does folate deficiency cause and look like

Answer 44

megaloblastic anaemia (cells enlarge) & large macrocytic red blood cells produced. - Giving someone folate with B12 deficiency will reduce megaloblastic anaemia occurring Folate and B12 deficiency can mask each other - this reduces O2 carrying capacity of blood – so causes anaemia - loss of appetite (anorexia), sore mouth and inflamed tongue - this causes depressed immunity, platelet and white blood cell division all reduce. So blood may not clot properly due to platelet reduction nerve degeneration & dementia drug induced (e.g. anti-epileptic drugs increase risk of neural tube defects) – making people more likey to folate deficiency