MODULE 2: Vitamin C

Question 1

Reduced form of vit C

Answer 1

Ascorbate

Question 2

Oxidized vitamin C form

Answer 2

Dehydroascorbate

Question 3

Absorption of vit C occurs where?

Answer 3

Throughout small intestine especially jejunum

Question 4

SVCT: what are and what do they transport

Answer 4

Specialized vitamin C transporters

Transport ASCORBATE

Question 5

What form of vit C do GLUTs transport (before absorption)?

Answer 5

Dehydroascrobate

Question 6

** % absorption of vitamin D relationship to DOSE SIZE

Answer 6

% absorption DECLINES with larger intake of vit C

Question 7

** Where is vit C stored/in high concentrations?

Answer 7

WBCs
Adrenals 
Pituitary 
Eyes 
Brain

Question 8

Oxalic acid and kidney stones

Answer 8

Oxalic acid = metabolite of vit C metabolism/excretion

Oxalic acid likely contributes to kidney stones

Question 9

** Vit C and Collagen Synthesis (involved in hydroxylations of what 2 amino acids?

Answer 9

Vit C involved in hydroxylations of proline and lysine (needed for synthesis of COLLAGEN)

Question 10

** Vit C, scar tissue, would healing

Answer 10

Vit C involved in synthesis of COLLAGEN which are important for would healing/scar tissue

Question 11

** Vit C and carnitine; function of carnitine

Answer 11

Vit C involved in SYNTHESIS of carnitine

Shuttle fatty acids into mitochondria (to enter TCA/Kreb)

Question 12

** Vit C, hydroxylation, neurotransmitters (2 specific)

Answer 12

Vit C facilitated HYDROXYLATION is required for the synthesis of NOREPINEPHRINE and SEROTONIN

Question 13

** Hydroxylation is process by which

Answer 13

HYDROXYL (OH) group is introduced to an organic compound (eg. Vit C hydroxylation required for synthesis of collagen)

Question 14

** Vit C & neurotransmitter and hormone synthesis via a ideation of peptides LOOK UP

Answer 14

Safe

Question 15

** Vit C and microsomal metabolism function/processing of complex molecules

Answer 15

Processes endogenous (cholesterol/hormones) and exogenous (toxins) substances

Acts as antioxidant during liver detox of complex molecules (dares ROS that are created during the detox pathways)

Question 16

** Vit C and cholesterol

Answer 16

Aids in the conversion of cholesterol to BILE ACIDS

Question 17

**Where does vit C act as an antioxidant in the body?

Answer 17

Aqueous tissue and tissue compartments (cytoplasm)

Question 18

** What is antioxidant activity of vitamin C (describe what that means)

Answer 18

Vit C is able to donate it’s available electrons in OH and carbonyl groups to terminate ROS

** Ascorbate READILY gives up electrons to reduce free radicals

Question 19

** In what occasion to vit C act as a PRO OXIDANT? Does it commonly occur?

Answer 19

Occurs during the interaction of ascorbate and minerals like IRON, COPPER

UNLIKELY to occur in the body (has only been seen in-Vivo)

Question 20

Hesperadin and vit C (pulp?)

Answer 20

Hesperadin (flavonoid; anti ox found in CITRUS)

Found in HIGHEST concentrations in pith(white membranous part of citrus and white part of PEEL)

Should consume citrus food in FULL FORM

Pulp is HIGHER is vit C/antioxidants

Question 21

Collagen is crucial for blood vessel X? And a fundamental protein for healthy ?

Answer 21

Blood vessel integrity

Healthy SKIN

Question 22

Hesperadin and chronic inflammation

Answer 22

Anti inflammatory effects help reduce markers of chronic inflammation

Question 23

Citrus bioflavonoids & BBB & antioxidant effects

Answer 23

Citrus bioflavanids (like hesperadin found in citrus fruit pith/membrane) can cross BBB and therefore exert antioxidant/anti inflammation effects in the brain

Question 24

** What lifestyle factors drive down levels of vit C in the body

Answer 24

Intense exercise 
Smoking 
Alcohol consumption 
STRESS 
Medications (amount) 
Drug user

Question 25

** HEMOCHROMATOSIS, vit C, & IRON (LOOK UP)

Answer 25

LOOK UP

Question 26

Vitamin C and Osteoarthritis/Degenerative Joint Disease

Answer 26

Protective role of vit C on osteoarthritis osteoBLASTS Antioxidant ability of vit C could help mediate decreased number of osteoblasts during again (that contribute to osteoarthritis) - Can INCREASE LIFESPAN on osteoblasts !

Question 27

** Food sources Vit C

Answer 27

Fruits and vegetables - citrus! - tomato - Strawberries - Green peppers etc.

Question 28

** Synthesis of vitamin C in mammals (EXCEPT HUMANS); Enzyme necessary?

Answer 28

Mammals can make vitamin C from GLUCOSE but humans lack the necessary enzyme to do so Enzyme = Gulonolactone oxidase

Question 29

Function SVCT1

Answer 29

Main carrier responsible for intestinal vitamin C absorption

Question 30

** Maximum body pool of vitamin C

Answer 30

2g

Question 31

Cosubstrate

Answer 31

Loosely bound coenzymes Function: Helps to FACILITATE REACTION OF ENZYMES

Question 32

** # vitamin C hydroxylation reactions required for collagen synthesis

Answer 32

3

Question 33

** Enzymes that vitamin C acts as a cofactors for in collagen synthesis; what amino acids are those enzymes used to form?

Answer 33

Prolyl hydroxylase (to make PROLINE) Lysyl hydroxylase (to make LYSINE)

Question 34

** Vitamin C, iron, collagen hydroxylation

Answer 34

Ascorbate acts as a REDUCING AGENT to convert oxidized iron (Fe3+) back to it’s reduced state (Fe2+) in the enzymes lysyl hydroxylase and prolyl hydroxylase

Question 35

**Vit C function in collagen and carnitine synthesis

Answer 35

Vit C acts as reducing agent (of iron) during hydroxylation reaction required for the synthesis of carnitine and collagen

Question 36

**Vitamin C hydroxylation function in norepinephrine synthesis

Answer 36

Norepinephrine is formed in the hydroxylation of the side chain of DOPAMINE

Question 37

** reducing agent means electron ??

Answer 37

DONOR

Question 38

** Vitamin C function: ANTIOXIDANT

Answer 38

Vitamin C acts as antioxidant in AQUEOUS environments (blood, within cell etc)

Question 39

** Vitamin C, glutathione, vitamin E relationship

Answer 39

Vitamin C REGENERATES antioxidants glutathione and vitamin E by contacting electrons

Question 40

** Non antioxidant functions of vitamin C

Answer 40

Collagen gene expression Synthesis of bone matrix Immune function

Question 41

Is vitamin C an effective prophylactic in cold incidence reduction?

Answer 41

NO; reducing colds if used low dose daily

Question 42

**Vitamin C and Iron interaction

Answer 42

Vitamin C ENHANCES absorption of IRON

Question 43

** RDA males/females; should it every increase?

Answer 43

Males 90mg Females 75mg INCREASE DURING PREGNANCY/BREASTFEEDING

Question 44

** Vit C: DEFICIENCY

Answer 44

``` Scurvy! Petechiae (ruptured small blood vessels) Bleeding gums Decaying teeth Abnormal wound healing ```

Question 45

** Vit C deficiency FOUR H’s

Answer 45

``` 4 H’s of scurvy Hemorrhagic Hyperkeratosis (hair follicles) Hypochondriasis Hematologic (Impaired collagen) ```

Question 46

** Vit C TOXICITY

Answer 46

Osmotic diarrhea Abdominal pain KIDNEY STONES (for those with renal dysfunction)

Question 47

** Upper limit vitamin C

Answer 47

2 g

Question 48

** Catecholamine hydroxylation pathway (phenylalanine —> Epinephrine)

Answer 48

Phenylalanine —> L-Tyrosine —> L-Dopa —> Dopamine —> Norepinephrine —> Epinephrine

Question 49

** Ascorbic acid acts as a pro-oxidant when???

Answer 49

Interacting with copper or iron; generates FREE RADICALS

Question 50

** Vitamin C is needed for the hydroxylation of??

Answer 50

Serotonin & Norepinephrine

Question 51

** Vitamins needed for carnitine synthesis

Answer 51

B6 & Vitamin C

Question 52

** Toxicity of vitamin C can result in

Answer 52

Kidney stones (for those with renal dysfunction) Excess iron absorption