Unit 9 - The Antioxidant Vitamins

Question 0

Identify vitamin A’s functions in the body.

Answer 0

• vision: combines with a protein (opsin) to form visual pigment (iodopsin)
• epithelial tissue development and maintenance - retinoic acid required in cellular differentiation to produce epithelial and mucous producing cells (goblet cells)
• Growth and bone development - differentiation of bone cells (osteoblasts and osteoclasts)
• Tooth development - enamel forming epithelial cells

Question 1

Identify the naturally occurring and biologically active forms of vitamin A.

Answer 1

• 3 forms of retinoids (retinol, retinal, retinoic acid)

- Beta- carotene (precursor found in vegetables)

Question 2

How prevalent is Vitamin A deficiency in Canada and what are the symptoms?

Answer 2

• actual deficiency is low in Canada but low intake is found is a sizeable portion of the population
• Symptoms: Blindness/ Night blindness, impaired immunity

Question 3

What are the therapeutic uses of vitamin A?

Answer 3

• treatment of skin disorders such as acne and psoriasis

- use for cancer prevention being researched

Question 4

What are the symptoms of vitamin A toxicity?

Answer 4

• blurred vision
• nausea
• vomiting
• vertigo
• reduced bone density

Question 5

What are some major food sources of vitamin A?

Answer 5

• deeply coloured fruits and vegetables *supply the precursor, beta-carotene
• dairy products
• butter/ margarine
• eggs

Question 6

Discuss the chemical stability of vitamin A.

Answer 6

• sensitive to oxidation by air in the presence of light

- removed with fat from foods such as milk (refortified in Canada)

Question 7

What is vitamin E’s function in the body as an antioxidant?

Answer 7

prevents the formation of free radicals (unstable molecules) by sacrificing itself to be oxidized instead of polyunsaturated fatty acids and other vulnerable components of the cell and cell membrane.

Question 8

What are the deficiency symptoms of vitamin E?

Answer 8

• capillary fragility (increased rupturing of red blood cells) - seen in premature infants
• deficiency is rare in human adults

Question 9

What benefits are claimed to be achieved from vitamin E supplements?

Answer 9

• protect against heart disease
• increase physical or sexual performance
• delay aging

Question 10

What are toxicity symptoms of vitamin E?

Answer 10

• Toxicity is rare because absorption decreases rapidly with increased intake.
• Some studies suggest that high doses may increase risk of mortality

Question 11

Discuss the chemical stability of vitamin E.

Answer 11

• easily destroyed by intense heat and exposure to oxygen

- major loss through the milling of grains

Question 12

What are the functions of vitamin C in the body?

Answer 12

• antioxidant - donates hydrogen atoms to other molecules to prevent oxidation of essential body compounds
• protects iron from being oxidized to support collagen synthesis
• participates in the conversion of some amino acids to essential body compounds.

Question 13

What are the deficiency symptoms of vitamin C?

Answer 13

a

Question 14

What are the toxicity symptoms of vitamin C?

Supplements of over 2g per day may cause toxicity but it is rare.

Answer 14

• nausea, abdominal cramps, diarrhea
• interference with the testing of urinary glucose
• blood cell breakage
• rebound scurvy

Question 15

What factors may influence requirements for vitamin C?

Answer 15

• smoking
• severe physical trauma - increased need for collagen
• severe emotional or environmental stress - increased stress hormone synthesis
• drug intake

Question 16

What are some major food sources of vitamin C?

Answer 16

Comes almost exclusively from fruits and vegetables

- citrus fruits, strawberries, kiwis, broccoli, bell peppers, brussels sprouts

Question 17

Discuss the chemical stability of vitamin C.

Answer 17

One of the most vulnerable vitamins to destruction

• dissolves readily in water
• easily oxidized (copper and iron cookware increase oxidation)
• sensitive to heat