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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
What are the consequences of vitamin A deficiency?
- Decreased cell division and deficient development - Night blindness - Xerophthalmia - Keratinization - Exhaustion - Death
26
What are the consequences of vitamin A toxicity?
- Death - Liver failure - Fractures - Bone abnormalities - Hemorrhages - Hair loss - Skin rashes
27
Name some good sources of vitamin A.
Beef liver, sweet potatoes, carrots
28
How would you increase vitamin A status (4)?
1) Eat more vitamin A rich foods 2) Drops every 6 months (expensive) 3) Fortify food supply (milk, sugar) 4) GMOs (golden rice)
29
What is the main function of vitamin K
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
What are the 2 forms of vitamin K.
- Phylloquinone | - Menaquinone
31
What is deficiency of vitamin K usually caused by?
- Fat malabsorption - Newborns (sterile gut) - Long-term antibiotic use - gut bacteria is killed off --> deficiency
32
What are sources of vitamin K?
- Anything that's really green | - Milk, eggs, broccoli, cabbage, liver
33
What are free radicals?
Unstable, highly reactive compounds that have an unpaired electrons (v short half-life). They oxidize lipids, fatty acids, DNA and proteins
34
What do antioxidants do?
Prevent or inhibit the oxidation of another | substance
35
What are the consequences of free radicals?
cancer, CVD, cataracts, compromised immune function | Contributes to damaged cells, and accelerates aging
36
How does a free radical form?
- 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
What is an example of an antioxidant?
Vitamin C (ascorbic acid)
38
What form is vitamin C in usually? What form can it become?
Exists in the reduced form, can be oxidized to prevent other compounds from being oxidized
39
Name 3 vitamin C functions.
``` – collagen • ‐ bone, teeth development • “cement”, scar tissue, wound healing – hormone synthesis – antioxidant, reducing agent ```
40
Name 2 consequences of scurvy.
- 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
How much vitamin C prevents scurvy? What is the RDA? How much for smokers?
- 10mg/d prevents scurvy - 75mg/d (men) - 90 mg/d (women) - Higher in smokers since they produce free radicals
42
How much vitamin C does fruit have? How many do you need? What is the best source of vitamin C?
Roughly 50 mg/d 2 fruits = 100 mg/d Red bell pepper
43
What are disadvantages of vitamin C megadoses?
``` – False positive urinalysis – Drug interactions – Oxidative stress: interaction with iron – kidney stones – rebound deficiency when pills stopped? ```
44
How does vitamin C megadoses interact with iron?
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
Name 3 roles of vitamin E.
– protects PUFAs in membrane lipids – protects lungs – protects lipids in foods
46
Why does vitamin E protect lipids?
Since it is lipid soluble
47
What is the name of vitamin E?
Tocopherol(s)
48
Name 3 consequences of vitamin E deficiency.
– RBCs break ‐ hemolysis – WBCs break ‐ immune function – cataracts, arthritis, cancer, fibrocystic breast disease, CVD (LDL oxidation)
49
What do free radicals cause? What do antioxidants do?
- Free radicals cause chain reactions that damage cellular structure - Antioxidants quench free radicals and protect cellular structures
50
Is beta-carotene a vitamin?
No it is an antioxidant, precursor for vitamin A which is NOT an antioxidant
51
Which minerals are antioxidants? Why?
Minerals that have 2 different valence states are often antioxidants as they are incorporated into metalloenzymes (Se, Mn, Zn, Fe)
52
What else can be an antioxidant?
- Glutathione - tripeptide - Phytochemicals (polyphenols, resveritrol, lutein, zeaxanthin) * not essential, but biological function
53
Name 4 vitamin E effects.
• Cataract prevention (decrease lipid px, enhance other antioxidant function) • Immune System function (protection of immune cells from free radicals) • Cancer • Neurological (Parkinson’s),
54
What are sources of vitamin E?
Vegetable oils, nuts, fruits, vegetables
55
What are the pros of supplementations?
``` – Correct deficiencies – Improve nutritional status – Decrease chronic disease risk – Support increased needs ‐ lifecycle, illness – Vegan diets ```
56
What are the cons of supplementations?
``` – Toxicity, poisoning – False sense of security – Bioavailability – Interactions – Unknown ideal supplement – Misinformation, claims – Cost ```
57
What are functional foods? Give examples.
``` foods that contain physiologically active compounds that provide health benefits beyond their nutrient contributions – Flax – Tomatoes – Blueberries – Salmon – Soybeans – Dark Chocolate ```
58
What are anthocyanins? What colour are they responsible for?
group of natural occurring pigments belonging to the flavonoid family, responsible for the red-blue colour of many fruits and vegetables
59
What is the largest group of water-soluble plant pigments?
Anthocyanins

1) Nutrition & Health (21 decks)

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