Consequences of Malnutrition Flashcards Preview

MD1 Metabolism > Consequences of Malnutrition > Flashcards

Flashcards in Consequences of Malnutrition Deck (61):
1

In which type of vitamin is overdose more likely: lipid-soluble, or water-soluble?

Lipid-soluble

2

Which type of vitamin needs to be replenished constantly: lipid-soluble, or water-soluble?

Water-soluble

3

Are vitamin and mineral deficiencies a big problem in Australia?

Low level problem but could be contributing to chronic disease

4

Why do vitamin and mineral deficiencies occur?

Modern Western diet can be poorly balanced/not variable enough
Individual diet may miss specific sources
Crops can lack nutrients because of availability in soil
Other disorders/lifestyles can interfere with absorption

5

In whom are vitamin and mineral deficiencies of concern?

Pregnant women
Young children
Elderly people

6

What does production of vitamin D need?

Exposure of skin to UV or dietary intake

7

In what foods is vitamin D found?

Fatty fish
Oysters
Eggs
Fortified margarine

8

Where does vitamin D act as a hormone?

Intestines
Kidneys
Bones

9

What are the roles of vitamin D?

Bone-making and maintenance by maintaining blood concentrations of Ca and P
- Enhances absorption from GIT
- Enhances re-absorption from kidneys
- Mobilises from bone into blood

10

How is vitamin D produced?

7-dehydrocholesterol > 2 steps in skin (using UV) > cholecalciferol (vitamin D3) > 1 step in liver/kidney > calcitriol

11

Is vitamin D3 active?

No

12

Is calcitriol active?

Yes

13

What happens in severe vitamin D deficiency in children?

Rickets
- Failure of normal calcification of bones
- Growth retardation
- Skeletal abnormalities
- Bent long bones of leg

14

Who are at higher risk of vitamin D deficiency?

Dark skinned people living very north/south
Fair skinned people who avoid sun exposure
Night shift workers, office workers, taxi drivers
Older people - skin, liver, and kidneys lose capacity to activate vitamin D
Older/disabled people who're housebound/in care
People covered for religious reasons

15

Wat happens in vitamin D deficiency in adults?

Loss of Ca from bones > fractures

16

What is the role of calcium in the bones?

99% of body's Ca in bones and teeth
Essential component of bone structure for rigid frame
Ca bank for blood levels Ca

17

What is the role of calcium in the blood?

1% in blood and cells
Part of many enzymes
Mediates hormonal responses
Essential for blood coagulation
Used in muscle contraction
Needed for neuromuscular function

18

Who are at risk of rising blood calcium?

Breastfeeding babies whose intake of milk high

19

How are falling blood calcium levels elevated?

1. Parathyroid hormone stimulates activation of vitamin D
2. Vitamin D and parathyroid hormone stimulate Ca reabsorption in kidneys
3. Vitamin D enhances Ca absorption in intestines
4. Vitamin D and parathyroid hormone stimulate osteoclasts > break down bone > release Ca into blood

20

What do blood levels of calcium indicate?

Nothing - they're always stable

21

How do you measure levels of calcium in bone?

No measures
Can measure bone mass and density

22

What foods in Australia are fortified?

Thiamine in bread
Folate and iodine in flour
Breakfast cereals voluntarily commonly fortified

23

What proportion of Australian women over 19 don't have an adequate intake of folate?

9%

24

Who are recommended to take extra folate?

All women of childbearing age

25

What does a folate deficiency in pregnancy cause?

Neural tube development defects; eg: spina bifida

26

What cellular processes need folate?

DNA
- Replication
- Repair
- Methylation
Especially relevant during rapid cell division and development

27

Why is it important to have adequate amounts of folate before you find out you're pregnant?

Neural tube development complete by 4 weeks
Very rare for woman to know she's pregnant at this time > don't often know until 6-8 weeks

28

What does folate deficiency in adults cause?

Macrocytic/megablastic anaemia
Characterised by large RBCs

29

Why does macrocytic anaemia occur in folate deficiency?

Slow repair of DNA damage

30

Is macrocytic anaemia because of folate deficiency common?

No, but some anticancer drugs can interfere with folate levels > deficiency

31

How is macrocytic anaemia treated?

Extra folate

32

What is the relationship between folate and vitamin B12?

Need each other for activation

33

What is vitamin B12 needed for?

Regenerated levels of methionine
DNA and RNA synthesis

34

Why do vitamin B12 levels decrease slowly?

Recycled for re-use

35

Where is vitamin B12 found?

Only in animal products
Almost all of vitamin B12 in plants inactive > vegans at risk of deficiency

36

How is folate activated?

Folate in food as polyglutamate = inactive
In intestine - breaks off glutamates > adds methyl groups > absorbed and delivered to cells = inactive
In cells trapped in inactive form
Vitamin B12 removes and keeps methyl group
- Removal of methyl activates folate
- Addition of methyl activates vitamin B12

37

How does a vitamin B12 deficiency lead to damage to myelin sheaths of peripheral nerves?

Levels of metabolic intermediates like methylmalonine CoA build up
Cause damage to myelin sheath

38

What are the symptoms of vitamin B12 deficiency?

Reduced performance on tests of intelligence and short-term memory
Creeping paralysis starting in extremities

39

What are the symptoms of an inability to activate folate?

Megablastic anaemia
- Often 1st symptom of vitamin B12 deficiency

40

What would be the effect of treating megablastic anaemia of a patient with vitamin B12 deficiency with folate?

Rapidly fix anaemia
Still have vitamin B12 deficiency
Peripheral nerve damage continues

41

What is the number one cause of preventable intellectual disability in children?

Iodine deficiency

42

What does a major iodine deficiency cause?

Goitre

43

Why may have mild iodine deficiency recently re-emerged in Australia?

Lower salt diet

44

Are difficulties in school caused by a mild iodine deficiency reversible with iodine supplementation?

Yes

45

What does severe iodine deficiency during pregnancy cause?

Severe and irreversible physical and mental retardation = cretinism

46

What is the most common deficiency in the world?

Fe

47

What is iron a part of?

Haemoglobin and myoglobin
P450 enzymes
Lysosomal enzymes
Ribonucleotide reductase

48

Why is iron never found free in the body?

Extremely toxic

49

How is iron kept in the body?

Bound to transport/storage proteins

50

From where is iron recycled in the body?

RBCs

51

How are iron stores depleted?

Shedding of intestinal and skin cells
Blood loss through menstruation in women

52

Why do children need more iron?

To increase blood volume

53

What is thiamine used for in the body?

Essential part of coenzyme thiamine pyrophosphate

54

What does severe thiamine deficiency cause?

Beriberi
- Oedema
- Muscle wasting

55

Is thiamine deficiency common in Australia?

No, rare
Except when caused by alcoholism

56

What are the dietary risks associated with alcoholism?

Low intake
Impaired absorption
Alterations in storage
Possibly increased excretion

57

How can absorption be impaired in alcoholism?

Damage to cells lining intestine
Alterations in function of pancreas > reduced digestive enzyme production
Alterations in fat absorption limits intake of lipid soluble vitamins
- A
- E
- D

58

How can storage be altered in alcoholism?

Decreased liver function > decreased vitamin A store

59

What vitamins and minerals are vegans at risk of being deficient in?

Vitamin B12
Vitamin D
Fe
Ca
Zn

60

Why are calcium and vitamin D important in the elderly?

Vital for preventing loss of Ca from bones > reducing risk of fractures

61

Why may the elderly develop deficiencies?

Harder to shop for fresh foods
Harder to cook
Could be cooking for just 1
Tastes and appetites change
Dental problems/dentures can make chewing harder
Changes in digestion and absorption through
- Age
- Disease
- Medication