Protein Intake And Metabolism Flashcards

1
Q

AMDR for 1-3 years of age

A

45-65% CHO
5-20% protein
30-40% fat

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2
Q

ADMR for 4-18 yrs

A

45-65% CHO
10-30% protein
25-35% fat

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3
Q

ADMR for 19 years and older

A

45-65% Cho
10-35% protein
20-35% fat

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4
Q

Practical issues/concerns with using 10-35% of total calories for protein

A
  • how would you know what to eat
  • how much protein to have at one time
  • would need to calculate energy needs (kcal/day)
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5
Q

What do most sport dieticians do to calculate AMDR for protein

A

Use values based on an athletes body weight

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6
Q

Example: energy needs 2,500 kcal/day, 21 yrs, protein range 250kcal to 875kcal

A

10%= 250kcal/4kcal per gram = 62.5g/day
35%= 875kcal/4kcal per gram = 218g/day

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7
Q

9 Protein functions

A
  1. Structural
  2. Transport
  3. Enzyme
  4. Hormone/neurotransmitter
  5. Immune
  6. Acid-base balance
  7. Fluid balance
  8. Energy (4kcal/g)
  9. Movement (skeletal muscle)
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8
Q

Structural

A

Vital constituents of all cells

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9
Q

Transport proteins

A

Of various substances in the blood

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10
Q

Protein for enzymes

A

Form almost all enzymes in the body

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11
Q

protein for hormone/neurotransmitters

A

Formation of insulin, etc

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12
Q

Protein for immune

A

Formation of antibodies, etc

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13
Q

Protein for acid-base balance

A

Buffering within the blood to maintain optimal pH

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14
Q

Protein for fluid balance

A

Exerting osmotic pressure to maintain optimal fluid balance within the body

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15
Q

What does protein contain

A

C,H,O and nitrogen

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16
Q

What does protein digestion enable

A

Amino acids to enter the “amino acid pool”
- blood, liver, peripheral tissues (i.e. muscle)
- broken down to AAs

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17
Q

Amino acids in one area are in constant

A

Equilibrium with another (tightly regulated)

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18
Q

Upon food digestion, how are proteins degraded

A

To amino acids by proteases (enzyme) in stomach and small intestine

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19
Q

What is protein broken down to in stomach

A

Polypeptides

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20
Q

What are polypeptides broken down into

A

Tripeptides, dipeptides, amino acids

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21
Q

Where does final breakdown to amino acids happen

A

In small intestine

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22
Q

Where are the amino acids absorbed

A

In portal vein and transported to liver
(Liver is critical centre in AA metabolism)

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23
Q

What is constantly clearing and moving AAs around body

A

Liver

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24
Q

How fast amino acids cleared once enter blood

A

5-10 mins
- certain digested quicker than others

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25
Q

Rate of digestion of protein is dependent on

A

Protein type and composition of the meal/snack

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26
Q

Fast absorption protein

A

Induce a large increase in whole body protein synthesis and oxidation with minimal affect on whole body protein breakdown

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27
Q

Example of fast absorption proteins

A

Whey or soy protein

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28
Q

Slow absorption protein

A

Induces a change in whole body protein turnover, small increase in synthesis and oxidation and a large reduction in protein breakdown

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29
Q

Example of slow absorption protein

A

Casein (e.g., chunks in cottage cheese)

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30
Q

How many amino acids

A

20

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31
Q

What is necessary for protein synthesis

A

All 20 amino acids

32
Q

How many indispensable amino acids/essential amino acids (EAA)

A

9

33
Q

What kind of AAs cannot be made in body

A

Indispensable amino acids/essential amino acids (EAA)

34
Q

3 branches chain amino acids (BCAA) (are also EAAs)

A

Leucine
Isoleucine
Valine

35
Q

What is ‘complete dietary proteins’

A

Food that contains all 9 EAAs
- e.g., meat

36
Q

Examples of 10-20g protein

A

2 eggs
3/4 cup Greek yogurt
48 almonds
1 1/2 cup tofu

37
Q

Plant sources of protein may result

A

In lower muscle protein synthetic response vs. Animal based protein

38
Q

Why may animal protein result in lower muscle protein synthetic response

A

EAA profile (lower leucine content)
Lower digestibility

39
Q

To get the quality of animal based protein what may you have to do with plant sources of protein

A

Portions may need to be larger

40
Q

What do you have to do with plant based dairy products

A

Check label
Make sure there is protein, calcium, vit d

41
Q

What do most nut based dairy products have

A

Low protein content

42
Q

Nitrogen balance

A

Ability of body to retain nitrogen (protein balance)
If in balance must be getting enough protein

43
Q

How to measure nitrogen balance

A

Dietary input (grams N2/day) = amount excreted
- amount consumed matches amount in urine

44
Q

Negative nitrogen balance

A

Amount excreted > dietary input

45
Q

Examples for negative nitrogen balance

A

Disease state, trauma, over-training
Individual is losing muscle protein

46
Q

Positive nitrogen balance

A

Retaining protein to support growth and development
Dietary input > amount excreted
E.g. adults on caloric sufficient diet

47
Q

How can nitrogen balance usually be maintained

A

When consuming 0.8 g/kg BW/day of protein in sedentary individuals (RDA)

48
Q

Nitrogen balance depends on

A

Adequate protein intake and total energy intake (kcal/day)
Need adequate nitrogen and amino acids

49
Q

A diet deficient in energy (kcal), despite adequate protein will result in

A

A negative nitrogen balance

50
Q

How long is protein digestion

A

Can take several hours
Fat, fibre, and protein can slow digestion down

51
Q

What is the most important metabolic fate of amino acids

A

Formation of body tissues, hormones, enzymes, antibodies, nucleotides, etc

52
Q

Why can humans not store amino acids

A

Due to inability to store excess nitrogen

53
Q

Since humans do not store AAs what occurs

A

Process of deamination in liver

54
Q

Deamination

A

Nitrogen (amino group) on the amino acid is removed leaving a carbon molecule (alpha-ketoacid) for oxidation

55
Q

What happens to excess nitrogen

A

Must be excreted
So the liver forms ammonia (NH3) from excess nitrogen

56
Q

What is pool of AAs in blood broken down into

A

Nitrogen and carbon residue(alpha keto acid) because of deamination

57
Q

What does nitrogen become

A

Urea (excretion)

58
Q

What happens to carbon residue (alpha ketoacids)

A

Become CHO
Or oxidized for energy

59
Q

What happens to the nitrogen group that travels to the liver in protein digestion

A

Gets converted to ammonia (NH3) and then converted to urea then enters kidneys to be excreted in urine

60
Q

What have increased levels of ammonia been associated with

A

Fatigue

61
Q

Glucogenic amino acids

A

Amino acids that can be used to form glucose via gluconeogenesis

62
Q

Ketogenic amino acids

A

Amino acids that are metabolized to acetyl-CoA and can enter the Krebs cycle or be converted to fat and used for energy

63
Q

What Alamo forms other nitrogen containing compounds

A

Amino acids

64
Q

What can liver use nitrogen-containing amino groups from excess AAs for

A

Combine them with alpha-ketoacids (from fat or CHO metabolism)

65
Q

When would an athlete need to use protein as a fuel source

A

Starvation

66
Q

During low CHO diets and starvation/fasting, crash diets what can happen

A

Fat and lean tissue can be used to fuel body
- when total amounts of CHO/fat/total calories limited

67
Q

Loss of lean tissue

A

Loss of strength/endurance, compromised immune/endocrine/musculoskeletal function

68
Q

When CHO availability is low=

A

Increased reliance on muscle/body protein stores for energy

69
Q

If an exercising individual wishes to maintain muscle mass what is essential

A

To not only have adequate protein for muscle growth but all sufficient CHO, fat and total calories

70
Q

What do calories from CHO and fat create

A

A protein sparing effect

71
Q

Low CHO diet may cause

A

Muscle protein to be oxidized for energy
- muscle
- liver (glucose or acetyl-CoA formation)

72
Q

Exercise may increase

A

Protein losses
- urinary, sweat, gastrointestinal

73
Q

What happens to protein at rest and exercise

A

Generally not oxidized to great extent and only contributes to ~5% of energy during exercise

74
Q

As intensity/duration increases what happens to protein

A

Increased protein catabolism when muscle glycogen depleted

75
Q

Although protein ca be incorporated to produced vast amounts of ATP what is problem

A

Rate of energy production is very slow vs CHO/fat

76
Q

In later stages of prolonged endurance exercise how much energy does protein supply

A

Up to 15%

77
Q

What does an increase in exogenous CHO intake during prolonged endurance exercise create

A

A muscle protein sparing effect
- inhibition of enzymes for protein breakdown