Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Nutrition > Vitamin A > Flashcards

Vitamin A Flashcards

1
Q

What is vitamin A?

A

A group of fat-soluble retinoids, including retinol, retinal, retinoic acid, and retinyl esters.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two groups of vitamin A in the diet?

A

Preformed vitamin A (retinoids) and provitamin A carotenoids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the most potent precursor of vitamin A?

A

β-Carotene.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name two other provitamin A carotenoids.

A
  • α-Carotene
  • β-Cryptoxanthin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is required for vitamin A absorption in the body?

A

Bile salts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the absorption percentage of retinol and β-carotene from dietary sources?

A
  • Retinol: 70-90%
  • β-Carotene: 20-50%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is most vitamin A stored in the body?

A

Approximately 90% is stored in the liver, primarily in stellate cells as retinyl esters.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is vitamin A transported in the body?

A

It is released into circulation bound to prealbumin (transthyretin) and retinol-binding protein (RBP).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens when the body’s vitamin A stores are depleted?

A

Vitamin A deficiency occurs, impairing physiological functions even before clinical eye signs appear.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the recommended daily intake of vitamin A for adults?

A
  • Males (>18 years): 900 μg RAE/day
  • Females (>18 years): 700 μg RAE/day
  • Pregnant women: 770 μg RAE/day
  • Lactating women: 1300 μg RAE/day
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is Retinol Activity Equivalent (RAE)?

A

The amount of vitamin A providing activity equivalent to:
* 1 μg all-trans-retinol
* 6 μg β-carotene
* 12 μg other provitamin A carotenoids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are rich food sources of vitamin A?

A
  • Plant: Carrots, dark green leafy vegetables.
  • Animal: Liver, cod liver oil.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the leading cause of preventable childhood blindness?

A

Vitamin A deficiency (VAD).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does VAD affect pregnant women?

A

It increases all-cause mortality and adversely affects pregnancy outcomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What percentage of women of childbearing age in the UAE have vitamin A deficiency?

A

3%, indicating a mild public health problem.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which age group is most vulnerable to VAD?

A

Preschool-age children.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why are preschool children more vulnerable to VAD?

A
  • High requirements for rapid growth
  • Transition from breastfeeding to other diets
  • Increased frequency of infections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which gender is more affected by night blindness and Bitot’s spots?

A

Males (1.2-10 times more than females).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why is VAD common in rice-dependent communities?

A

Rice is low in vitamin A, and such communities have limited dietary diversity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What physiological stages increase the risk of VAD in women?

A
  • Pregnancy (especially last trimester)
  • Lactation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Name some conditions associated with secondary vitamin A deficiency.

A
  • Liver diseases
  • Protein-energy malnutrition (PEM)
  • Malabsorption (e.g., cystic fibrosis, chronic diarrhea, bile duct obstruction)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the early manifestations of VAD?

A

Increased rates of infections due to compromised epithelial barriers and immune system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is xerophthalmia?

A

A term that includes all ocular manifestations of vitamin A deficiency.

24
Q

List the stages of xerophthalmia.

A
  • Night blindness
  • Conjunctival xerosis
  • Bitot’s spots
  • Corneal xerosis
  • Corneal ulcers and keratomalacia
25
Q

How can early stages of xerophthalmia be treated?

A

Vitamin A supplementation can lead to complete recovery.

26
Q

What are the risk factors for VAD?

A
  • Age (preschool children)
  • Gender (more common in males)
  • Pregnancy and lactation
  • Poor diet and breastfeeding practices
  • Infections and intestinal parasites
  • Low socio-economic status
27
Q

How does VAD interact with infectious diseases?

A

VAD increases infection severity, and infections reduce vitamin A intake and accelerate its loss, worsening deficiency.

28
Q

What is the relationship between VAD and protein-energy malnutrition (PEM)?

A

VAD often coexists with PEM and delays recovery from corneal xerophthalmia.

29
Q

How does seasonality affect VAD?

A

Vitamin A and carotene availability fluctuate, with deficiencies emerging during summer diarrhea seasons.

30
Q

How can xerophthalmia be prevented?

A

Through adequate maternal vitamin A storage, prolonged breastfeeding, and improved dietary intake.

31
Q

Which form of vitamin A is predominantly stored in the liver?

A

Retinyl esters.

32
Q

What percentage of vitamin A in the liver is stored in stellate cells?

A

90-95%.

33
Q

Which protein helps vitamin A circulate in the body?

A

Retinol-binding protein (RBP).

34
Q

What is the conversion factor of IU Retinol to RAE?

A

0.3 μg RAE.

35
Q

What is the most common cause of primary vitamin A deficiency?

A

Dietary inadequacy.

36
Q

Which disorder interferes with vitamin A absorption by impairing bile acid production?

A

Bile acid insufficiency.

37
Q

What is the term for white plaques on the conjunctiva due to VAD?

A

Bitot’s spots.

38
Q

In which country is VAD considered a mild public health issue based on serum retinol levels?

A

UAE.

39
Q

Which physiological condition has the highest demand for vitamin A?

A

Lactation.

40
Q

Which organ, apart from the liver, stores small amounts of vitamin A?

A

Kidney.

41
Q

What is the prevalence of VAD-related night blindness in preschool-age children globally?

A

45 countries.

42
Q

Which intestinal parasite increases the risk of vitamin A deficiency?

A

Giardiasis.

43
Q

What stage of xerophthalmia is characterized by granular dryness of the cornea?

A

Corneal xerosis.

44
Q

What is the primary risk factor for xerophthalmia in children?

A

Early cessation of breastfeeding.

45
Q

Which communities are most prone to VAD due to dietary practices?

A

Rice-dependent communities.

46
Q

Which carotenoid has the highest vitamin A activity?

A

β-Carotene.

47
Q

What is the estimated absorption percentage of β-carotene from dietary sources?

A

20-50%.

48
Q

What condition involves fat-soluble vitamin malabsorption, including vitamin A?

A

Pancreatic insufficiency.

49
Q

What term is used to describe all ocular manifestations of vitamin A deficiency?

A

Xerophthalmia.

50
Q

Which vitamin A deficiency stage causes reduced ability to see in dim light?

A

Night blindness.

51
Q

What percentage of vitamin A is stored in fat depots, lungs, and kidneys?

A

10%.

52
Q

What is the primary dietary source of preformed vitamin A?

A

Animal foods.

53
Q

Which socio-economic factor correlates closely with VAD?

A

Economic deprivation.

54
Q

What is the primary factor responsible for vitamin A deficiency in ‘rice-dependent’ communities?

A

Low dietary diversity.

55
Q

What is the primary impact of VAD on epithelial barriers?

A

Compromised integrity leading to increased infection rates.

Nutrition (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions