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Food and Nutrition 1030 > Lecture 13 - Antioxidants > Flashcards

Lecture 13 - Antioxidants Flashcards

1
Q

What is the role of antioxidants?

A

To protect cells from oxidative damage

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2
Q

What are the agents that protect from oxidative damage?

A

Vitamins quench the radicals

Minerals act as cofactors for enzymes

Phytochemcials

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3
Q

What is a free radical?

A

Something with an unpaired electron which damages lipids DNA RNA and proteins

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4
Q

What neutralizes free radicals?

A

Antioxidants

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5
Q

What is the definition of quench?

A

To get rid of, eliminate

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6
Q

What can antioxidants be thought of?

A

Dominos, a vitamin would sit inform of the domino to prevent the others from following

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7
Q

Why are minerals required for antioxidants?

A

They themselves aren’t antioxidants, but they are just required for the function

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8
Q

What creates free radicals?

A

Any normal reaction in the body

Sun

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9
Q

What are the available forms of vitamin A?

A

Retinyl Esters: True vitamin a

Beta Carotene: Precursor for vitamin a (not true)

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10
Q

Where are Retinyl esters in the body?

A

Bonded to fat in the body. Esters will separate from fat to just have retynil

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11
Q

What is the storage form of Vitamin a

A

Retinal

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12
Q

What is retinol involved in?

A

Vision related

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13
Q

How do we end up with retinal?

A

Retinyl (from animal foods) > Converted to retinol > converted into retinal

Beta-carotene (from plants) > Converted to retinal

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14
Q

In the body, what are the different conversions of all the retinoids?

A

Retinol< >Retinal> Retanoic acid

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15
Q

What happens when we have too much retinal?

A

It can be converted back to retinol

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16
Q

What is the hormone version of vitamin a?

A

Retanoic Acid

-involved in DNA, transcription, Cell division, growth, reproduction

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17
Q

Do carotenoids all have the same antioxidant activity?

A

Yes, but not all of them are converted to vitamin a

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18
Q

What is the pathway for vitamin a once it has been ingested?

A

It is fat soluble and will end up in the chylomicrons then into the lymph and blood. Once in the blood it binds to binding proteins to be carried within the body

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19
Q

Where is vitamin a role in protein synthesis and cell differentiation

A

Takes place in epithelial cells on the skin and in the mucos membranes. Vitamin a is there to make sure those cells divide properly
-promotes differentiation of epithelial and goblet cells

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20
Q

How does vitamin a help with reproduction and growth?

A

Sperm development
Fetal development
Bone remodelling
Failure of growth in children

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21
Q

What does vitamin a deficiency look like?

A

Vitamin a status

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22
Q

What is vitamin a status?

A

Amount of vitamin a for you to use is dependant on how much is in your liver as well as your protein status

23
Q

What happens to vitamin a when you don’t have enough protein?

A

It won’t transport vitamin a

24
Q

What is vitamin a deficiency dependent on?

A

Vitamin a status and protein tatus

25
Q

Where is vitamin a stored?

A

In the liver

26
Q

What results from a vitamin a deficiency?

A
  • Infectious disease
  • Night blindness (lack of rhodopsin and inability to recover from changes in light)
  • Xerophthalmia (total blindness due to drying and softening of cornea)
  • Keratinization
27
Q

How does vitamin a toxicity occur?

A

When binding proteins in the blood become swamped, the vitamin isn’t excreted quickly so the free vitamin a can cause damage
-not seen with beta-carotene

28
Q

Why isn’t vitamin a a treatment for acne?

A

Vitamin a itself is not used as a treatment for acne but the retinoid used to treat acne have no vitamin a activity

29
Q

What are some sources of beta carotene?

A

Yellow+Green veggies
-any vegetable really

Preformed vitamin a in any animal protein with some fat

30
Q

What is RAE and what are the conversions??

A

Retinal activity equivalent

1microgram of preformed vitamin a= 1RAE

12micrograms of beta-carotene= 1RAE

31
Q

What is vitamin e role as an antioxidant?

A

Primary defender against free radicals

  • prevents more free radicals from producing more free radicals
  • cell membranes and other lipids
  • oxidizes LDL
32
Q

What is the other name for vitamin e?

A

Tocopherol

-alpha is the main type

33
Q

How does vitamin e reduce the oxidization of LDL?

A

Vitamin e sits in LDL and reduced the oxidation of LDL

-blood vessels see the oxidized LDL as the enemy

34
Q

Can you become vitamin e deficient?

A

Primary deficient is rare (fat malabsorption mainly)

-Can present in infants

35
Q

What happens when you are vitamin e deficient?

A

Red blood cells break open due to oxidization of PUFAs in RBC membranes
-causes Erythrocyte Hemplysis

36
Q

Can you become toxic from vitamin e?

A

Very rare, liver regulated vitamin e

-may interfere with blood clotting because vitamin e is a blood thinner, thus interfering with vitamin k

37
Q

What is the UL for vitamin e?

A

set 65x higher than the recommended value

-based on alpha tocopherol

38
Q

What happens to vitamin e when there is an increase if PUFA?

A

There is an increase need for vitamin e

39
Q

What is a source of vitamin e?

A

Mostly vegetable oils

-easily destroyed by heat and oxidation

40
Q

What is vitamin c role in the body as an antioxidant?

A

Loses electrons easily to stop free radical damage
-enhances iron absorption

Cofactor for collagen
-facilitates the binding of collagen fibres

Stress
-adrenal glands secrete vitamin c

41
Q

What is the real name of vitamin c?

A

ascorbic acid

-anti scurvy

42
Q

How much vitamin c do we need to prevent scurvy and to saturate tissue

A

10mg/day to prevent scurvy

100mg/day to saturate tissues

43
Q

Why do smokers need more vitamin c?

A

Smokers are ingesting more chemicals that cause damage, in order to counteract the free radicals, more vitamin c is needed

44
Q

What is the RDA for vitamin c?

A

It is set 7x higher than the amount deeded to prevent scurvy

45
Q

Why is vitamin c harmful for kidneys?

A

Vitamin c is not stored in the body, and is excreted through the kidneys. If too much is being secreted it could damage kidneys

46
Q

What does vitamin c deficiency look like?

A

Scurvy: bleeding gums and breaking capillaries

inadequate collagen, wound heal thing stops, loose teeth, dry skin

47
Q

What does vitamin c toxicity look like?

A

Very rare

-GI distress, diarrhea

48
Q

What does vitamin c have adverse effects on?

A

Iron overload

49
Q

Why is Se important in antioxidants?

A

Part of glutathione peroxidase

-works synergistically with vitamin E

50
Q

Where do you find Se?

A

Found in soils and leaches into foods

In some amino acids

51
Q

Can you become deficient in Se?

A

Yes, but rare, ,most Canadians meet the RDA for Se

-UL set

52
Q

Which vitamins work synergistically with each other?

A

E with Se
E with A
C with E

-they don’t work in isolation

53
Q

What are the 2 lines of defence against free radicals?

A
  1. Antioxidant enzyme defence system

2. Antioxidant nutrients including photochemicals

54
Q

What is atherosclerosis?

A

When LDL is oxidized to atherosclerosis

Food and Nutrition 1030 (20 decks)

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