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1) Nutrition & Health > Vitamin K, Vitamin A, Antioxidants and Supplementation > Flashcards

Vitamin K, Vitamin A, Antioxidants and Supplementation Flashcards

1
Q

What is the safe range of intake graph? Where does RDA and UL go?

A

Learn it.

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2
Q

Which micronutrient is a worldwide concern and the biggest issue for children? How many?

A

Vitamin A
100 million children
500 000 children become blind and 100 000 children die

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3
Q

What is the function of vitamin A? It can decrease the fatality from what? What can toxicity of vitamin A cause?

A

Immune system, cell differentiation

  • Vitamin A decreases fatality from measles
  • Can cause birth defects with toxicity
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4
Q

What is the alcohol form of vitamin A? The aldehyde form? The acid form? What is the precursor? Which is the hormone form?

A
  • Alcohol: retinol
  • Aldehyde: retinal
  • Acid: retinoic acid
  • Beta-carotene
  • Retinoic acid is the hormone
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5
Q

What is beta-carotene composed of?

A

2 vitamin As stuck together

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6
Q

Is all beta-carotene converted to vitamin A? Is it as well absorbed?

A

Not all beta-carotene is converted to vitamin A, and absorption of beta-carotene is not as efficient as that of vitamin A.

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7
Q

How is vitamin A activity from precursors measured?

A
  • retinol activity equivalents (RAE)

- Average efficiency of conversion of beta-carotene and other carotenes to form vitamin A

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8
Q

What is retinol converted to? What does retinol come from?

A 
Retinal
Retinyl esters (animal foods)
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9
Q

Where do retinal and retinoic acid come from?

A

Beta-carotene

Fruits and vegetables

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10
Q

Which step in the interconversion of vitamin A is slow?

A

Retinal to retinoic acid (the hormone form)

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11
Q

What is the first symptom of vitamin A deficiency?

A

Night blindness, never adapt to the darkness

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12
Q

As light enters the eye what absorbs the light?

A

Rhodopsin within the cells of the retina

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13
Q

What are retina cells composed of?

A

Several layers of cells: Rods (see low intensity light) and cones (see colour)

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14
Q

How do we see?

A

Light comes through the lens and hits the photoreceptor cells sends a nerve impulse to the brain (visual cortex) and you can see

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15
Q

What is vitamin A’s role in vision? Which version of vitamin A?

A
  • cis-Retinal
  • Rhodopsin contains cis-Retinal
  • When a photon strikes the rod that imparts energy to the retinal and the double bonds are changed from cis to trans, which means it is no longer bound and released
  • > opsin protein changes configuration and sends and electrical impulse to the brain
  • we can recycle the retinal back so we can see the low-intensity light again BUT if we are deficient in vitamin A, we can’t recycle, so we can’t adapt to low-intensity light
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16
Q

What is rhodopsin composed of?

A

Retinal + opsin

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17
Q

As deficiency of vitamin A progresses, what happens?

A

Hormonal problems related to retinoic acid (particularly the structure of the cornea - highly specialized differentiation in cells is not maintained)

  • Bitot’s spots
  • Xerophthalmia
  • Keratomalacia (irreversible)
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18
Q

What do the epithelial cells secrete in vitamin A deficiency?

A
  • They secrete the protein keratin in a process known as keratinization
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19
Q

How does vitamin A deficiency affect cell differentiation?

A
  • Normally mucous membranes (trachea, lungs, GI tract) are columnar epithelial differentiating cells and there is an intact barrier
  • Without vitamin A, they lose their function, lose their ability to produce mucus, and the barrier function is destroyed -> more vulnerable to infection
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20
Q

Name the 3 functions of retinoic acid.

A

1) Cell differentiation
2) Immunity
3) Growth

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21
Q

How does vitamin A control gene expression to affect cellular differentiation?

A

–function of goblet and epithelial cells (mucous membrane lining defensive barrier)
– affects embryonic development

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22
Q

What are the consequences of vitamin A deficiency in terms of cell differentiation?

A

–  membrane integrity, taste, digestion, absorption

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23
Q

What is the effect of toxicity of vitamin A during pregnancy?

A

malformations in all organ systems

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24
Q

How does vitamin A indirectly affect immunity? Direct?

A

Indirect: Epithelial barrier
Direct: immune system (HIV, malaria, upper respiratory tract infections, diarrhea)

25
Q

What are the consequences of vitamin A deficiency?

A
  • Decreased cell division and deficient development
  • Night blindness
  • Xerophthalmia
  • Keratinization
  • Exhaustion
  • Death
26
Q

What are the consequences of vitamin A toxicity?

A
  • Death
  • Liver failure
  • Fractures
  • Bone abnormalities
  • Hemorrhages
  • Hair loss
  • Skin rashes
27
Q

Name some good sources of vitamin A.

A

Beef liver, sweet potatoes, carrots

28
Q

How would you increase vitamin A status (4)?

A

1) Eat more vitamin A rich foods
2) Drops every 6 months (expensive)
3) Fortify food supply (milk, sugar)
4) GMOs (golden rice)

29
Q

What is the main function of vitamin K

A

Taking the carboxyl group off the R group of glutamate in the post-translational processing of certain proteins, once it is off, calcium can bind to the protein (important in bone mineralization and the blood clotting process)

30
Q

What are the 2 forms of vitamin K.

A
  • Phylloquinone

- Menaquinone

31
Q

What is deficiency of vitamin K usually caused by?

A
  • Fat malabsorption
  • Newborns (sterile gut)
  • Long-term antibiotic use - gut bacteria is killed off –> deficiency
32
Q

What are sources of vitamin K?

A
  • Anything that’s really green

- Milk, eggs, broccoli, cabbage, liver

33
Q

What are free radicals?

A

Unstable, highly reactive compounds that have an unpaired electrons (v short half-life). They oxidize lipids, fatty acids, DNA and proteins

34
Q

What do antioxidants do?

A

Prevent or inhibit the oxidation of another

substance

35
Q

What are the consequences of free radicals?

A

cancer, CVD, cataracts, compromised immune function

Contributes to damaged cells, and accelerates aging

36
Q

How does a free radical form?

A
  • Normally, O contains 8 electrons.
  • Occasionally O will accept an unpaired electron during the oxidation process
  • This acceptance of a single electron causes oxygen to become an unstable molecule called a free radical
37
Q

What is an example of an antioxidant?

A

Vitamin C (ascorbic acid)

38
Q

What form is vitamin C in usually? What form can it become?

A

Exists in the reduced form, can be oxidized to prevent other compounds from being oxidized

39
Q

Name 3 vitamin C functions.

A 
– collagen
• ‐ bone, teeth development
• “cement”, scar tissue, wound healing
– hormone synthesis
– antioxidant, reducing agent
40
Q

Name 2 consequences of scurvy.

A
  • Scorbutic gums. Unlike other lesions of the mouth, scurvy presents a symmetrical appearance without infection.
  • Pinpoint hemorrhages. Small red spots appear in the skin, indicating spontaneous bleeding internally.
41
Q

How much vitamin C prevents scurvy? What is the RDA? How much for smokers?

A
  • 10mg/d prevents scurvy
  • 75mg/d (men) - 90 mg/d (women)
  • Higher in smokers since they produce free radicals
42
Q

How much vitamin C does fruit have? How many do you need? What is the best source of vitamin C?

A

Roughly 50 mg/d
2 fruits = 100 mg/d
Red bell pepper

43
Q

What are disadvantages of vitamin C megadoses?

A 
– False positive urinalysis
– Drug interactions
– Oxidative stress: interaction with iron
– kidney stones
– rebound deficiency when pills stopped?
44
Q

How does vitamin C megadoses interact with iron?

A

Act as a reducing agent and reduce iron that is bound to transferrin –> ferrous, no longer bound to protein, now free iron, which is a potent pro-oxidive - Fenton Reactions

45
Q

Name 3 roles of vitamin E.

A

– protects PUFAs in membrane lipids
– protects lungs
– protects lipids in foods

46
Q

Why does vitamin E protect lipids?

A

Since it is lipid soluble

47
Q

What is the name of vitamin E?

A

Tocopherol(s)

48
Q

Name 3 consequences of vitamin E deficiency.

A

– RBCs break ‐ hemolysis
– WBCs break ‐ immune function
– cataracts, arthritis, cancer, fibrocystic breast disease, CVD (LDL oxidation)

49
Q

What do free radicals cause? What do antioxidants do?

A
  • Free radicals cause chain reactions that damage cellular structure
  • Antioxidants quench free radicals and protect cellular structures
50
Q

Is beta-carotene a vitamin?

A

No it is an antioxidant, precursor for vitamin A which is NOT an antioxidant

51
Q

Which minerals are antioxidants? Why?

A

Minerals that have 2 different valence states are often antioxidants as they are incorporated into metalloenzymes (Se, Mn, Zn, Fe)

52
Q

What else can be an antioxidant?

A
  • Glutathione - tripeptide
  • Phytochemicals (polyphenols, resveritrol, lutein, zeaxanthin)
  • not essential, but biological function
53
Q

Name 4 vitamin E effects.

A

• Cataract prevention
(decrease lipid px, enhance other antioxidant function)
• Immune System function (protection of immune cells from free radicals)
• Cancer
• Neurological (Parkinson’s),

54
Q

What are sources of vitamin E?

A

Vegetable oils, nuts, fruits, vegetables

55
Q

What are the pros of supplementations?

A 
– Correct deficiencies
– Improve nutritional status
– Decrease chronic disease risk
– Support increased needs ‐ lifecycle, illness
– Vegan diets
56
Q

What are the cons of supplementations?

A 
– Toxicity, poisoning
– False sense of security
– Bioavailability
– Interactions
– Unknown ideal supplement
– Misinformation, claims – Cost
57
Q

What are functional foods? Give examples.

A 
foods that contain physiologically
active compounds that provide health benefits beyond their nutrient contributions
– Flax
– Tomatoes
– Blueberries
– Salmon
– Soybeans
– Dark Chocolate
58
Q

What are anthocyanins? What colour are they responsible for?

A

group of natural occurring pigments belonging to the flavonoid family, responsible for the red-blue colour of many fruits and vegetables

59
Q

What is the largest group of water-soluble plant pigments?

A

Anthocyanins

1) Nutrition & Health (21 decks)

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