Vitamin C

Question 1

Who cannot synthesize vitamin C?

Answer 1

primates, bats, guinea pigs, lack of gulonolactone oxidase

Question 2

Vitamin C sources

Answer 2

papaya, oranges, orange juice, cantaloupe, cauliflower,
broccoli, Brussels sprouts, green peppers, grapefruit,
grapefruit juice, kale, lemons, strawberries

Question 3

Vitamin C can be destroyed by:

Answer 3

Light, heat, oxidation and alkaline solutions

Question 4

Vitamin C is stable in :

Answer 4

acidic solutions

Question 5

What are the 5 function of vitamin C

Answer 5

1. antioxidant
2. collagen synthesis
3. carnitine synthesis
4. tyrosine synthesis from phenylalanine
5. neurotransmitter

Question 6

Explain Vitamin C role as an antioxidant

Answer 6

Reducing agent
* Reverse oxidation by donating electrons and hydrogen ions
decrease free radicals and reactive oxygen species (oxygen
components that are highly oxidative, i.e. OH., O2-, H2O2, HO2.)
* I.e. attack lipids and protein in membranes such as oxidizing LDL

Question 7

Explain Vitamin C role in collagen synthesis

Answer 7

Hydroxylation reactions of proline and lysine are necessary for
collagen formation

Question 8

Explain Vitamin C role in carnitine synthesis

Answer 8

involved in lipid metabolism

Question 9

Explain Vitamin C role as a neurotransmitter

Answer 9

I.e., serotonin, dopamine, etc.

Question 10

What are the 5 physiological effects of vitamin C

Answer 10

1. treatment of cold and cancer
2. wound healing/decreased risk of infection
3. enhances iron absorption
4. prevent of CVD
5. prevention of cataracts

Question 11

Vitamin C symptoms

Answer 11

-Scurvy: bleeding gums, petechia, perifolliculosis
* Develops within 2-3 months when no C given
* 10 mg usually adequate for prevention

Question 12

What groups are at risk for vitamin c deficiency

Answer 12

• Smokers: RDA is actually greater +35 mg/d
• Decreased status in smokers from NHANES II
• Lower absorption
• Higher turnover
• Elderly
• Lower status compared to younger
• Dietary habits, tooth loss, economic status may play
  roles
• Smoking inc free radicals
• increased turnover (may stem from similarity to
  glucose)
• Others: alcoholics, surgical patients, OC users

Question 13

Vitamin C toxicity symptoms

Answer 13

1. rebound scurvy
2. renal stones
3. diarrhea

Question 14

Vitamin C interactions

Answer 14

increased iron absorption
decreased copper absorption
conver vitamin E to reduced form
increased excretion of heavy metals

Question 15

how are vitamin c levels assessed

Answer 15

• Blood, serum, plasma levels of ascorbate
• May also measure levels in white blood cells