Vitamins - Water Soluble and Fat Soluble

Question 1

What are vitamins?

Answer 1

Organic compounds with essential biochemical functions that are not made by the body

Question 2

What are the water soluble vitamins?

Answer 2

thiamin (B1), riboflavin (B2), niacin (B3), pyridoxine (B6), pantothenic acid, biotin, folate, cobalamin (B12), and vitamin C (ascorbic acid)

Question 3

What are the fat soluble vitamins?

Answer 3

A, D, E, and K

Question 4

Vitamin deficiencies are

Answer 4

rare in healthy individuals on well-balanced diets

Question 5

Vitamin deficiencies are important to consider

Answer 5

for unusual diets, during growth, in disease, and in developing countries

Question 6

Fat soluble vitamin digestion is compromised by

Answer 6

pancreatic insufficiency or bile blockage

Question 7

Water soluble vitamins are taken up by

Answer 7

the intestine

Question 8

Vitamin K has no RDI because

Answer 8

it is made by gut flora

Question 9

PLP

Answer 9

pyridoxal phosphate (B6)

Question 10

NAD

Answer 10

niacin (B3)

Question 11

CoA

Answer 11

Pantothenic acid

Question 12

FMN, FAD

Answer 12

riboflavin (B2)

Question 13

THF

Answer 13

folate

Question 14

Thiamin (B1) is critical for

Answer 14

decarboxylations; carbohydrate, protein, and fat metabolism; nerve function

Question 15

Deficiency of thiamin (B1) causes

Answer 15

beriberi (polished rice); Wernicke-Korsakoff (alcoholics)

Question 16

Sources of thiamin (B1) include

Answer 16

vegemite, wholemeal breads, fortified cereals

Question 17

Thiamin (B1) is a component of which enzyme?

Answer 17

Pyruvate dehydrogenase

Question 18

Why is thiamin (B1) critical to nerve function?

Answer 18

It links anaerobic and aerobic metabolism (on which nerves rely) by pyruvate dehydrogenase

Question 19

What is the role of riboflavin (B2)?

Answer 19

electron carrier - flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD); carb, protein, and fat metabolism

Question 20

Sources of riboflavin (B2) include

Answer 20

vegemite, milk, cheese, fortified cereals

Question 21

Deficiency of riboflavin (B2)

Answer 21

is rare, usually only seen in chronic alcoholics with other deficiencies

Question 22

What is the role of niacin (B3)?

Answer 22

coenzyme; electron carrier (NADH, NADPH); carb, protein, and fat metabolism

Question 23

Sources of niacin (B3)

Answer 23

Vegemite, wheat bran, fortified cereals

Question 24

Niacin (B3) deficiency

Answer 24

seen in alcoholics; Pellagra (dermatitis, diarrhoea, dementia, death)

Question 25

Sources of pyridoxine (B6)

Answer 25

Vegemite, nuts, bananas, fortified cereals

Question 26

Role of pyridoxine (B6)

Answer 26

amino acid metabolism (transamination)

Question 27

Deficiency of pyridoxine (B6)

Answer 27

rare; need varies with protein intake; linked to original contraceptive pill in 60s

Question 28

What is the role of biotin?

Answer 28

carboxylation in proteins (eg Acetyl-coA carboxylase to produce Malonyl-CoA); glucose, fat, amino acid biosynthesis

Question 29

Sources of biotin include

Answer 29

brewer's yeast, cooked egg yolk (raw has avidin, antagonist of biotin); soy beans

Question 30

Deficiency of biotin

Answer 30

caused by avidin in raw eggs, results in scaly, shiny, dry skin

Question 31

What is the role of folate?

Answer 31

critical in DNA synthesis

Question 32

Sources of folate include

Answer 32

green vegetables, liver, fortified cereals

Question 33

Deficiency of folate

Answer 33

occurs commonly in elderly and chronic alcoholics; causes spina bifida if in pregnancy; causes macrocytic anaemia and glossitis (pillae die on tongue)

Question 34

RDI for folate is

Answer 34

400ug/day (previously 120ug/day)

Question 35

Folate supplementation may be linked to

Answer 35

increased rates of cancer due to its role in DNA synthesis

Question 36

What is the role of cobalamin (B12)?

Answer 36

coenzyme containing cobalt; folate metabolism in DNA synthesis; transalkylations in nerves and blood

Question 37

Sources of cobalamin (B12)

Answer 37

Meat, egg yolks, cheese

Question 38

Deficiency of cobalamin (B12)

Answer 38

common in vegans and IF deficiency (genetic or autoimmune); causes pernicious anaemia with yellowish skin and faint icterus of sclerae due to bilirubin, lightening of hair and irises; peripheral neuritis

Question 39

Intrinsic factor

Answer 39

glycoprotein produced by parietal cells of stomach necessary for B12 absorption; genetic or autoimmine deficiencies tx with B12 injections

Question 40

What is the role of vitamin C?

Answer 40

cofactor in collagen synthesis (proline hydroxylase adding -OHs to prolines on outside of collagen that allow it to H-bond and give it strength); neurotransmitter metabolism; iron absorption; antioxidant

Question 41

Sources of vitamin C

Answer 41

citrus fruit, cabbage

Question 42

Deficiency of vitamin C

Answer 42

scurvy

Question 43

What is the role of vitamin A?

Answer 43

half of B-carotene; produces retinal (night vision) and retinol (epithelium growth in skin and eyes)

Question 44

Sources of vitamin A

Answer 44

B-carotene (coloured vegetables)

Question 45

Vitamin A deficiency

Answer 45

xeropthalmia (dry eye) caused by retinol deficiency can lead to blindness if not treated

Question 46

What is the role of vitamin D?

Answer 46

Ca2+ regulation and bone development - facilitates uptake of Ca2+ in gut which prevents it being absorbed from bones; mediates protection against infection, cancer, and autoimmune disease

Question 47

Sources of vitamin D include

Answer 47

derived from cholesterol and synthesized with UV light and hydroxylations in liver and kidney to form calcitriol (hormone)

Question 48

Deficiency of vitamin D

Answer 48

rickets in children (knock knees and bow legs); osteomalacia in adults (Ca taken from bones if can't get it from gut)

Question 49

Vitamin D status is assessed by measuring

Answer 49

25OH-D; <25nmol/L = deficiency

Question 50

What is the role of vitamin E?

Answer 50

antioxidant in membranes to accept free radicals; linked to signalling in inflammation and cell division

Question 51

Sources of vitamin E include

Answer 51

high levels in seed oils

Question 52

What is the role of vitamin K?

Answer 52

important in blood clotting - essential for the gamma-glutamyl carboxylase that adds a carboxyl group to glutamic acid eresidues on II, VII, IX, and X to activate them

Question 53

Vitamin K deficiency

Answer 53

inadequate clotting and haemorrhage