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FST2201 : Introduction to human nutrition > W7: vitamins > Flashcards

W7: vitamins Flashcards

1
Q

What are the fat-soluble vitamins?

A

Vitamin A,D,E,K

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2
Q

What are the differences between fat-soluble vitamins and water-soluble vitamins? [4]

A
  1. fat soluble vitamins require bile for digestion and absorption
  2. Fat soluble vitamins travel through lymphatic system while water-soluble vitamins absorbed directly into bloodstream.
  3. Excess fat soluble vitamins are stored in liver and adipose tissue while excess water-solbule vitamins is excreted in urine
  4. Risk of toxicity for fat soluble vitamins is significantly higher than water-soluble vitamins (excess consumption)
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3
Q

Fat soluble vitamins

What is the precursor to vitamin A?

Where is vit A stored?

A

Beta-carotene

  • Stored in liver
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4
Q

Fat soluble vitamins

What are the general functions of Vitamin A? [2]

A
  1. transports proteins (retinol binding protein)
  2. involved in cell signaling(retinoic acid receptor)
    - cell signalling and nerves to see
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5
Q

Fat soluble vitamins

What are the three different forms of Vitamin A?

A
  1. Retinol
  2. Retinal
  3. Reinoic acid

(alcohol, aldehyde, carboxylic acid)

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6
Q

Fat soluble vitamins

What are some excellent (and sometimes unusual) sources of Vitamin A? [3]

A
  1. Beef liver
  2. Sweet potatoes
  3. Mango
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7
Q

Fat soluble vitamins

What are the usual sources of Vitamin A? [4]

A
  1. Brocolli
  2. Carrots
  3. Tomato juice
  4. Fortified corn flakes

carrot and tomato juice : beta carotene

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8
Q

Fat soluble vitamins

In general, what are the sources of Vitamin A? [2]

A
  1. Dark green and deep orange fruits and vegetables
  2. fortified foods
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9
Q

Fat soluble vitamins

The first active form of Vit A is retinol. What are the functions of retinol? [3]

A

REPRODUCTION AND DEVELOPMENT
1. Sperm development
2. Normal fetal development
3. Child growth (bone remodeling)

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10
Q

Fat soluble vitamins

Where is retinal found?

A

Retina cells

  • the cells of retina contain rhodopsin, which is made of opsin (protein) + cis-retinal
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11
Q

Fat soluble vitamins

What is the function of retinal?

What happens when light is abosrbed by a substance in retina cells?

A

It is the basis of phototransduction
- when** rhodopsin absorbs light**, retinal changes from cis to trans configuration, triggering an electrical impulse that carries visual information to the brain through the optic nerve

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12
Q

Fat soluble vitamins

What are the 2 functions of retinoic acid?

A

Protein synthesis and cell differentiation (especially for epithelial cells)

  1. Increases skin cell production
  2. Maintains healthy cells in mucous membranes

It is found in “retinol products” in skincare

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13
Q

Fat soluble vitamins

What can Vitamin A deficiency lead to? [3]

A

1) Change in shape and size of epithelial cells
- Skin becomes dry, rough and scaly
- Normal digestion and absorption of nutrient from GI tract affected
- Weaken defenses in respiratory tract, vagina, inner ear and urinary tract, increasing risk of infectious disease

2) Night blindness due to inadequate supply of retinal to retina

3) Blindness
- develops in stages
- Due to lack of vitamin A in cornea

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14
Q

Fat-soluble vitamins

What are the 2 sources of vit A toxicity?

A

High concentrations of vit A in:
- animal sources (liver of animals)
- Supplements

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15
Q

Fat-soluble vitamins

What are the effects of Vit A toxicity? (excess consumption)[3]

A
  1. Bone defects which may weaken bones
  2. Birth defects → cell death in spinal cord
  3. Acne (vit A/retinol is also used in treatment of acne but side effects include skin dryness, sensitivity of skin)

BBA

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16
Q

Fat-soluble vitamins

Beta carotene is a precursor for Vitamin A synthesis. What is the side effect of excess consumption of beta carotene, and in what 3 ways beta carotene can be in excess?

A

Beta carotene excess leads to yellow / orange skin occur from:
- Overconsumption of foods (yellow, orange, and green leafy fruits and vegetables)
- Overconsumption of supplements
- Inefficient conversion of beta carotene to other forms

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17
Q

Fat-soluble vitamins

What are the sources of Vitamin D? [3] List examples where applicable

A
  1. sunlight exposure
  2. Obtained from diet
    - Vitamin D2: plants
    - Vitamin D3: animal sources –> Oily fish, egg yolks, and fortified milk
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18
Q

Fat-soluble vitamins

What are the functions of Vitamin D in the body? [2]

A
  1. Cause bone growth by increasing absorption of calcium and phosphorus.
  2. May enhance/suppress gene activity.
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19
Q

Fat-soluble vitamins

What factors can lead to Vitamin D deficiency?[3]

A
  1. dark skin – a lot of pigments in skin, sunlight cannot pass through
  2. lack of sunlight exposure
  3. not using fortified milk
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20
Q

Fat-soluble vitamins

Vitamin D defiency can also lead to ____ deficiency

A

Calcium

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21
Q

Fat-soluble vitamins (vit D)

What are the effects of calcium deficiency in
1. children
2. adults
3. elderly

A
  1. Children → development of rickets, where bones don’t calcify properly and bones bend
  2. Adults → Osteomalacia : poor mineralisation of bone, leading to soft/brittle/deformed bones
  3. Elderly → Osteoporosis : loss of calcium from bones, bones susceptible to fractures
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22
Q

Fat-soluble vitamins

Which Vitamin is most likely of all vitamins to have toxic effects, and is most commonly used supplement consumed among fat soluble vitamins?

A

Vit D

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23
Q

Fat-soluble vitamins

There is no risk of toxivity if Vit D is synthesised through sun exposure. What are factors affecting amount of sun exposure a person receives? [4]

A
  1. Skin color
  2. Latitude (which hemisphere you are in, in the world)
  3. Season
  4. Time of day
24
Q

Fat-soluble vitamins

What is the effect of Vit D toxicity?

A

Excess consumption of Vit D raises blood calcium concentrations, causing calcification in soft tissues + hardening blood vessels

25
Q

Fat-soluble vitamins

What is the process of activating Vitamin D in the body? What is the precursor of Vit D?

A

Vitamin D is activated through a two-step hydroxylation process that occurs first in the liver and then in the kidneys.

  • precursor: cholesterol
26
Q

Fat-soluble vitamins

What are the functions of fat-soluble vitamins A, D, E, and K together?

A
  • Fat-soluble vitamins A, D, E, and K function together in bone growth and remodeling
  • vitamins A and E also have antioxidant properties.
27
Q

What is B Vitamins mainly involved in? What kinds of cells does a deficiency in B Vitamins affect?

A

B Vitamins are co-enzymes which assist enzymes mainly involved in energy metabolism

B Vitamin deficiency mainfly affects fast growing cells like skin, intestinal cells and nerves.

28
Q

Water-soluble vitamins

What are the sources of Vitamin B1 (thiamin)?[2,4]

A
  • cornflakes
  • tomato juice

Excellent but sometimes unusual sources: PLSS
- pork chop
- lean meat
- soy milk
- squash (plant – herbaceous fruits in the gourd family)

29
Q

Water-soluble vitamins

What are the functions of Vitamin B1 (thiamin) in the body? [2]

A
  • Vitamin B1 is a component of the coenzyme thiamin pyrophosphate (TPP) , which is involved in energy metabolism, helping the body’s cells change carbohydrates into energy.
  • Vit B1 is important for nerve and muscle function.
30
Q

Water-soluble vitamins

What is the disease caused by Vitamin B1 deficiency? What are the 2 forms of the disease and what do they mean?

A

beriberi
- Dry beriberi : affects nervous system (e.g. weakness in muscle)
- Wet beriberi : affects cardiovascular system → cardiovascular damage and water retention

31
Q

Water-soluble vitamins

Vit B1, thiamin, is not sensitive to degradation. True or false?

A

False, it is destroyed by prolonged cooking.
It leaches into water when boiling / blanching foods

32
Q

Water-soluble vitamins

Vit B3, niacin, exists in 2 coenzyme forms that are involved in metabolic reactions. What are these 2 forms?

A
  1. Nicotinamide adenine dinucleotide (NAD)
  2. NADP (phosphate form of NAD)
33
Q

Water-soluble vitamins : Vit B3

What are some sources of niacin? [3]

A
  1. Liver
  2. mushroom
  3. chicken

LMC

34
Q

Water-soluble vitamins

What is the consequence of Vit B3 deficiency?

A

Pellagra (rough or painful skin)

35
Q

Water-soluble vitamins

Naturally occuring forms of Vit B3/ niacin does no harm. However, what is the side effect of oveconsuming niacin with supplements/drugs, and is it harmful?

A

“niacin flush” → skin flushes red but generally harmless

36
Q

Water-soluble vitamins

What is the primary coenzyme form of folate (Vit B9)?

A

Tetrahydrofolate (THF)

37
Q

Water-soluble vitamins

What are the functions of folate? [2]

Hint:Nothing to do with skin/intestinal cells/nerve cells

A
  1. Converts vit B12 to coenzyme form
  2. Transfers single-carbon compounds during metabolism
38
Q

Water-soluble vitamins

What are the 3 general food sources of folate (Vit B9)? List 2 examples.

A

Come from:
1. naturally occurring food sources
2. fortified foods
3. supplements
- Broccoli, asparagus

39
Q

Water-soluble vitamins

Folate is not prone to processing methods. True or False?

A

False, folate is sensitive to heat and oxidation.

40
Q

Water-soluble vitamins

What are some side effects of folate deficiency? [3]

A
  1. Impaired** cell division **and protein synthesis
  2. Anemia – not enough red blood cells
  3. GI tract detioriation
41
Q

Water-soluble vitamins

What are the side effects of folate toxicity?

A

Nil, folate toxicity is rare

42
Q

Water-soluble vitamins

Folate is used as a prevention of what kind of defects in fetus?

A

Neural tube defects, where spinal cord does not close properly

  • Supplements are consumed 1 month before conception / through first trimester
  • Fortified grain products help too
43
Q

Water-soluble vitamins

What is a major safety concern with eating high doses of supplementation of folate?

A

Can hide symptoms of vitamin B12 deficiency, such as anemia and neurological damage.
-This means that the person may not know that he has vit B12 deficiency and may not treat the root cause of vit B12 deficiency

44
Q

Water-soluble vitamins

Vitamin B9 (folate) and vitamin ____ depend on each other for activation

A

B12

45
Q

Water-soluble vitamins

What are the functions of Vit B12?[2]

A
  1. Regeneration of methionine
  2. synthesis of DNA and RNA
46
Q

Water-soluble vitamins

Vit B12is almost exclusively found from what kind of products? List 2 examples

A

Found almost exclusively from animal products
- Fish and milk have good bioavailability of vit B12

47
Q

Water-soluble vitamins

Vitamin B12 are easily destoryed in food processing methods. True or False?

A

False, it is relatively stable in food processing methods

48
Q

Water-soluble vitamins

Presence of Vit ____ accelerates vit B12 degradation but has little relevance in food.

A

C

49
Q

Water-soluble vitamins

Though Vitamin B12 deficiency is rare, but if there is a deficiency, what is it due to?

A

Inadequate absorption of Vit B12, where there is lack of hydrochloric acid / intrinsic factor protein (glycoprotein secreted by stomach which binds with B12 to be absorbed into small intestine)

50
Q

Water-soluble vitamins

Vitamin B12 deficiency is most likely to be found in ____ diets.

What is the main consequence of Vit B12 deficiency?

A

Vegan diets

Vit B12 deficiency leads to anemia and neurological damage

51
Q

Water-soluble vitamins

Is there Vit B12 toxicity (excessive consumption)?

A

No, there is also no upper limit

52
Q

Water-soluble vitamins

What are the 6 functions of Vit C?

A
  1. Antioxidant which defends against free radicals which lose electrons easily → Vit C donates electrons to electron deficient free radicals
  2. Protects tissues from oxidative stress, preventing disease

3. Enhances iron absorption

  1. Cofactor in collagen formation
  2. Cofactor in other reactions like hormone synthesis
  3. Prevention and treatment of common cold
    - Note : conflicting and controversial research
    - Vit C may deactivate histamine
53
Q

Water-soluble vitamins

What are the 5 signs of vitamin C deficiency?

A
  1. Gums bleed easily around teeth
  2. Capillaries under skin break spontaneously
  3. Scurvy (delayed wound healing)
  4. Psychological signs – adverse mood (depression), cognitive impairment
  5. Sudden death
54
Q

Water-soluble vitamins

What is the maximum amount of vit C that can be absorbed?

A

200 mg per day

55
Q

Water-soluble vitamins

What is the upper limit of vit c for adults?

A

2000 mg

FST2201 : Introduction to human nutrition (10 decks)

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