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Nutrition > Antioxidants > Flashcards

Antioxidants Flashcards

1
Q

Why is vitamin A a deficiency you do not want?

A

Night blindness = early symptom
Regulates gene expression, important in protein synthesis and cell differentiation - can cause tissue degeneration, impaired growth and development, decreased immune defense

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2
Q

How is vitamin A metabolized?

A

Fat-soluble, requiring digestive enzymes and bile to separate it out form food and form micelles.

Travels w/chylomicrons or in portal circulation to liver

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3
Q

What is vitamin A the leading cause of in developing countries?

A

Preventable blindness (permanent damage to the eye)

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4
Q

What are the degenerative changes associated with eye tissues that occur in severe Vitamin A deficiency?

A

Xerophthalmia and Bitot’s spots

Corneal ulceration, scarring and blindness

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5
Q

When is an Recommended Dietary Allowance created?

A

When there is abundant research/evidence existing to reach consensus on human requirement

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6
Q

Can you see Recommended Dietary Allowance and Adequate Intake for the same vitamin?

A

No, RDA means there’s sufficient evidence for adequate human consumption and AI is used instead of RDA when evidence is not sufficient to reach consensus

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7
Q

What is a Tolerable Upper Level of Intake?

A

A level that, when exceeded, may present some risk to the patient

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8
Q

What is the Daily Value?

A

On nutrition labels, it lets us know how much of a vitamin or mineral we are getting, in accordance to what we need daily… Currently based on 1968 RDAs for vitamins and minerals

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9
Q

What is considered the level of acute or chronic toxicity?

A

> 25,000 IU/day (mostly overdoing the supplements)

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10
Q

What are the adverse effects of lower amounts of vitamin A that are still above the RDA? (There are 2)

A

Risk of birth defects >10,000 IU/day

Risk of bone loss and fracture >5,000 IU/day

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11
Q

Can you get too much Vitamin A by taking in too much of the carotenoid source of the vitamin? (Getting vitamin A from plants)

A

No! They don’t pose risks

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12
Q

What are the toxicity symptoms for vitamin A?

A

Headache (intra-cerebral swelling), bone/joint pain, skin changes, liver damage, systemic symptoms

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13
Q

What is ascorbic acid?

A

Vitamin C

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14
Q

Can humans make vitamin C?

A

Nope! Have to get it in the diet

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15
Q

What are the functions of vitamin C in terms of the immune system?

A

It orchestrates function of both innate and adaptive immune system, influencing both cellular and humoral immune responses

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16
Q

Do we metabolize large amounts or small amounts of vitamin C best?

A

Small amounts! We don’t want to overwhelm our gut with too much vitamin C

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17
Q

What is vitamin C a coenzyme for?

A

Collagen synthesis **
SYnthesis of some NTs, hormones and other biomolecules
Cholesterol conversion to bile acids
Catabolism of hormones, drugs and toxins

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18
Q

What does vitamin C facilitate absorption of?

A

Iron

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19
Q

What are the signs of scurvy (vitamin C deficiency)?

A

Connective tissue pathologies
Petechial hemorrhages
Loose teeth
Bone deformities in children

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20
Q

What do you have to do with vitamin C and smokers?

A

Oxidative stress causes smokers to require 35mg more to maintain similar blood levels of vitamin C to healthy people

21
Q

Where does the jury stand on vitamin C and it’s protection on the person from the common cold?

A

Some athletes may find vitamin C supplementation helpful for preventing colds

May be worthwhile for common cold patients to test whether it has a therapeutic effect for them

22
Q

What molecule is vitamin C made from?

A

Glucose! (Modified corn syrup….)

23
Q

True or false: Natural vitamin C is chemically identical to synthetic vitamin C

A

True

24
Q

Is a “natural” vitamin C supplement better than synthetic or as good as eating the food it was extracted from?

A

Nope.. Unimpressive. Just for marketing!

25
Q

What are mineral ascorbates?

A

Less acidic form of ascorbic acid (take off the proton and add a mineral for people who cannot tolerate excess acidity)

26
Q

What is Ester-C?

A

An attempt at making vitamin C more fat soluble! Didn’t show evidence of superiority except reduced gastric sensitivity so don’t waste your dollars!

27
Q

Is vitamin C potentially toxic in large amounts?

A

Nope, UNLESS you have kidney stones - “despite conflicting results, it may be prudent for individuals predisposed to oxalate kidney stone formation to avoid high-dose vitamin C supplementation”

28
Q

Why would vitamin C have a tolerable Upper Limit? (It does)

A

Trying to prevent GI upset and diarrhea from excess absorbed vit C (excess vit C has an osmotic effect pulling water into the bowels)

29
Q

How many vitamin E isoforms are there?

A

8 total
4 tocopherols
4 tocotrienols

30
Q

What is the designation for natural vitamin E to look for on a label?

A

D- or RRR stereoisomer

31
Q

What is the chemical designation to look for on a label for synthetic vitamin E?

A

Dl- or “all-rac”

32
Q

How do companies protect the antioxidant effect of vitamin E?

A

Esterification - still allows you to use the vitamin E (look for -el at the end of the vitamin E on the label)

33
Q

True or false: we are unable to get vitamin E from supplements that have gone through esterification

A

False - our body is able to do de-esterification of vitamin E by a digestive process before it can be absorbed and utilized

34
Q

Can you absorb D-tocopheryl on your skin?

A

No, your skin doesn’t break down vitamin E the way your digestive system can

35
Q

Rhodopsin

A

Facilitates vision in low light situations

Essential component of vitamin A

36
Q

What do you look for when identifying an esterified vitamin E?

A

tocopherYL followed by “acetate” or “sulfate”

37
Q

What is the vitamin E form that the liver secretes and why?

A

Only alpha-tocopherol

Because hepatic alpha-tocopherol transfer protein selects it for incorporating the alpha isoform into VLDL particles

38
Q

What happens to gamma-tocopherol, tocotrienols and other isoforms in the body?

A

They’re metabolized in the liver and excreted. We aren’t 100% sure what they do in the body before being excreted, maybe have some activity in the gut

39
Q

What are the functions of alpha-tocopherol?

A

It’s a potent anti-oxidant in lipid environments, maybe helping the immune system via membrane activity

40
Q

What is the most abundant tocopherol in our diet?

A

Gamma-tocopherol due to its presence in plant-based oils and nuts

41
Q

What is the most abundant tocopherol in body tissues?

A

Alpha-tocopherol!

42
Q

Is vitamin E deficiency something you’ll likely see in practice?

A

No, it’s really rare and usually associated with impaired fat absorption or genetic defects.

May see suboptimal intake which is common! Causes increase in cardiovascular risk

43
Q

Which vitamin is commonly missing from people’s diet and results in lots of people getting less than their RDA?

A

Vitamin E

44
Q

What are the best food sources of vitamin E?

A

Vegetable oils, nuts, whole grains, green leafy vegetables and fortified foods

45
Q

How should you take for fat-soluble supplements?

A

With food!

46
Q

What are seeing with vitamin E in observational studies?

A

Those who take Vitamin E or have acceptable blood levels are linked to lower cardiovascular disease (but they may also just be HEALTHIER)

47
Q

What have intervention studies shown about vitamin E and its efficacy for protecting against cardiovascular disease?

A

No benefit as an intervention against cardiovascular disease

48
Q

What are the risks of vitamin E supplementation in very sick people?

A

Increased mortality in chronic disease taking large doses of synthetic or alpha-only vitamin E (natural is best)

Nutrition (1 decks)

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