Protein and Amino Acid Requirements Flashcards
1
Q
We determine how much protein we need via what 5 things
A
1) Requirement
2) DRI
3) RDA: meets 97-98% of populayion
4) AI
5) EAR: Meets 50% needs of the population 2 standard deviations from RDI
2
Q
What must provide requirements for maintenance and any special needs of growth, reproduction and lactation.
A
Dietary Protein Requirement
3
Q
The lowest level of dietary protein intake that will balance the losses of nitrogen from the body, and thus maintain the body protein mass in persons at energy balance with modest levels of physical activity.
A
Dietary Protein Requirement
4
Q
What populations should have a higher intake of protein and why?
A
Children and pregnant of lactating women, due to deposition of tissues or the secretion of milk at rates consistent with good health.
5
Q
The IOM, Food and Nutrition Board, and the NAtional Academy of Sciences set which requirement?
What countries to they set them for?
A
DRI’s
United States and Canda
6
Q
What is the Adult EAR for Protein?
A
Adult EAR: 0.66 g/kg body weight
7
Q
What is the Adult EAR for Protein?
A
Adult RDA: 0.80 g/kg body weight
8
Q
WHO/FAO/UNU sets what?
What countries do they set them for?
A
Food and Agricultural Organization
The rest of the World
9
Q
What are the two methods to determine protein requirements?
A
Factorial Method and Nitrogen Balance Method
10
Q
Which method is not currently used to estimate protein requirement?
A
Factorial Method
but it is used for other nutrients, i.e. zinc requirements
11
Q
Which method that was used to estimate the most recent protein requirements (DRI 2005)?
A
Nitrogen Balance Method
12
Q
Why is the factorial method not used?
A
It underestimates protein requirements
13
Q
Which method measures obligatory nitrogen loss in persons on diets devoid of protein, but adequate in energy and other nutrients?
A
Factorial Method
Loss of nitrogen on a nitrogen free diet
14
Q
What is Obligatory Nitrogen Loss?
A
Loss in urine, feces, sweat and minor routes (hair, nails, sloughed skin, body secretions, etc.)
- Men lose more than women
Men 50 mg N.kg-1.d-1.
Women 35 mg N. kg-1.d-1.
Average 47 mg N. kg-1.d-1.
15
Q
Since no protein is fed, there is no way of estimating dietary protein digestibility or utilization by the body
This is a problem in which method?
A
Factorial
16
Q
There are technical difficulties in accurately estimating losses (urine, sweat, dermal, etc)
This is a problem in which method?
A
Factorial
17
Q
With low protein intake (or in protein deficiency) adaptation and accommodation occurs which skew the results
This is a problem in which method?
A
Factorial
18
Q
In a protein free diet, in which everything else stays normal, about how many days does it take before Nitrogen levels hit a steady states (aka nitrogen levels decrease for how many days before becoming stable?)
A
7-8 days
19
Q
Can nitrogen excretion ever reach zero?
A
No
20
Q
Do you lose more nitrogen when you are fasting or when you are on a low protein diet?
A
Fasting
21
Q
Are fasting and starvation different? How so?
A
Yes,
Fasting don’t eat for a while and starvation means you are not eating anything
22
Q
What involves calculating the difference (per day) between nitrogen intake and amount excreted in urine, feces, sweat and dermal losses?
A
Nitrogen Balance
23
Q
Nitrogen balance =
give a formula
A
g of N eaten – g of N lost
24
Q
Who is in nitrogen balance?
A
Stable weight healthy adults
25
Who is in positive nitrogen balance? (3)
Growing infants and children
Pregnant and lactating women
Individuals performing weight bearing exercises
26
Who is in negative nitrogen balance?
Individuals in the catabolic state (stress, trauma, infection, etc.)
Individuals on weight reducing diets
Individuals consuming inadequate protein
27
Growing infants and children are in what type of nitrogen balance?
Positive
28
Pregnant and lactating women are in what type of nitrogen balance?
Positive
29
Individuals performing weight bearing exercises are in what type of nitrogen balance?
Positive
If you eat 100g protein, you will excrete 80 because 20 will go to muscle building. Thus, you took more in that you put out so you are in positive nitrogen balance. Make more muscle denovo
30
Individuals in the catabolic state (stress, trauma, infection, etc.) are in what type of nitrogen balance?
Negative
31
Individuals on weight reducing diets are in what type of nitrogen balance?
Negative
32
Individuals consuming inadequate protein are in what type of nitrogen balance?
Negative
33
Stable weight healthy adults are in what type of nitrogen balance?
Balanced
34
More nitrogen taken in than lost
Positive Nitrogen Balance
35
More nitrogen lost than taken in
Negative Nitrogen Balance
36
Hadaad Notes: Nitrogen Balance
Nitrogen balance is the classic approach, which has been used for almost all determinations of protein requirement and a large number of studies of amino acid requirements since the pioneering work of Rose. The basic concept is that protein is by far the major nitrogen-containing substance in the body, so that gain or loss of nitrogen from the body can be regarded as synonymous with gain or loss of protein. Second, it is implicit in the method that in the healthy subject, body nitrogen will be constant (in the adult) or increasing maximally (in the growing child) if the dietary intake of the specific test nutrient, such as an indispensable amino acid, is adequate. It follows from this that if body nitrogen is decreasing or is not increasing adequately, then the diet is deficient.
Estimates of protein requirements have been determined by studying groups of people fed different amounts of protein, in order to determine the minimum intake that will permit them to maintain N equilibrium. At intakes below their requirement, they will show negative N balance.
37
Which methods involves placing subjects on diets adequate in all nutrients except for the one being tested (ie, protein)
The Nitrogen balance method
38
Subjects are placed in random order on diets containing various levels of protein (example 0.2 g/kg, 0.3 g/kg, 0.4 g/kg, 0.6 g/kg), each for a number of days to achieve a steady state, and then urine, feces, and dermal samples are collected to measure nitrogen losses
Nitrogen balance method
39
True or False? Nitrogen balance is then computed for each level of intake
True: Theoretically, the lowest level of N intake needed to achieve nitrogen balance represents the protein “requirement.”
40
Major challenge with nitrogen balance method
To determine exactly where the zero balance point occurs
41
Graph: "Response of N balance to increasing amounts of whole-egg protein added to a protein-free diet"
1) What is the order: conservation, theoretical requirement then N equilbrium
conservation--> theoretical requirement --> actual requirement
42
What is another name for actual requirement ?
N equilibrium
43
Is Nitrogen balance graph linear?
No, it is not linear, the slope changes as intake approaches the balance point
44
What are the reasons Nitrogen balance is not linear?
1) There are technical difficulties associated with the exact measurement of intake and output
2) The length of time needed to achieve steady state is often longer than that used in N balance experiments
3) The influence of other dietary factors such as calories, essential amino acids, and nonessential amino acids may influence balance
4) It is possible to maintain N equilibrium at any level of protein intake above the minimum requirement. Intake in excess of requirements does not lead to positive N balance, but simply leads to excretion of more end-products of amino acid catabolism, so that balance is maintained
45
True or False:
| Excess energy intake improves N Balance and, thus, underestimates requirement needed at maintenance energy intakes.
True
46
What are two specific problems with Nitrogen balance? (2 terms)
Adaptation and Accomodation
47
In the N balance method, what is the process that permits the organism to response to a dietary change without adverse consequences?
Adaptation
- body adapts and the body response fine to a reduced amount of a nutrient
48
In the N balance method, what is the process that permits the organism to response to dietary change that favors survival of the individual but may result in losses in some important functions
Accommodation
- changes happen, but you don't see it ex: losing protein from muscle, "you don't really see it"
49
True or False:
| If you intake less Cals you need more protein
True
50
True or False:
| How much you feed people affects to balance point?
True
51
Is the body more efficient when it has less or more calories?
Less calories, but eventually it will resort to breaking down protein if your cals are too low
52
Does gender affects ages 0-18 in regards to the recommend intakes of high-quality reference protein for normal humans (EAR and RDA's)
No
53
When does gender come into play in regards to the recommend intakes of high-quality reference protein for normal humans (EAR and RDA's)
ages 14+
54
>18 years old EAR
0.66 g/kg/d
55
>18 years old RDA
0.80 g/kg/d
56
Hadaad Notes: Recommended Intakes of High-Quality Reference Protein for Normal Humans. (IOM 2002)
Recommended Intakes of High-Quality Reference Protein for Normal Humans. (IOM 2002)
EAR (estimated average requirement): the intake that meets the estimated nutrient needs of half of the individuals in a group.
RDA (recommended dietary allowance): the intake that meets the nutrient need of almost all (97.5%) of individuals in a group.
Value for infants in the first half-year of life is the adequate intake estimate determined in that population that appears to sustain a defined nutritional status, including growth rate, normal circulating nutrient values, and other functional indicators of health. This value is not equivalent to an RDA.
Data from FNB/IOM. Proteins and amino acids. In: Dietary Reference Intakes for Energy, Carbohydrate, fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academy Press, 2002, with permission.
57
Criteria for valid nitrogen balance measurement of protein requirements
Caloric intake must match caloric requirement
An appropriate stabilization period must precede each measurement
Periods on the same diets must be long enough to establish a stable response to the dietary change
Degree of depletion of the subject must be taken into account
No infections, even of seemingly mild degree, can be present
Variations in daily physical activity must be minimal
Fluid intake must be controlled
Correction must be made for integumental and miscellaneous losses
Subjects should not be anxious or otherwise disturbed
Protein intake must be precisely monitored
Urine collections must be precisely timed and complete
Fecal collections must be complete and very well homogenized before a sample is taken for analysis
58
What factors that influence protein requirements are accounted for by the RDA?
- Physiological state: growth, pregnancy, lactation, elderly, etc.
- Body weight
59
What factors that influence protein requirements are not accounted for by the RDA?
- Infections, fevers, burns, surgical trauma, accidents, etc.
- Muscular activity, exercise
60
What two methods are used to access AA requirements?
1) Nitrogen balance
| 2) Isotopic tracer methods
61
Isotopic tracer methods include what 3 things?
Direct amino acid oxidation (DAAO)
Indicator amino acid Oxidation (IAAO)
Indicator amino acid oxidation and balance (IAAO/IAAB)
62
What classical method is used to access AA's
Nitrogen balance studies with diets containing adequate total protein and all amino acids except the one being studied (the test amino acid)
Nitrogen Balance Method
- eat everything you want except the AA you want to test
63
In which test is the:
Amino acid is fed at graded levels and nitrogen balance is calculated
- Problems similar to those associated with nitrogen
balance studies
Nitrogen Balance Method
64
True or False:
The body can synthesize protein if you don't have all the AA's
False
65
True or False:
In the Nitrogen Balance diet, you basically have to follow a chemical diet because its hard to isolate one AA because they are present in many foods
True
66
Is Histidine an essential or non-essential AA?
Essential
67
What are sources of histidine in the body which may provide histidine to achieve nitrogen balance on a histidine-free diet
- Carnosine (beta-alanyl histidine)
- Anserine (beta-alanyl-1-methyl histidine)
- Balenine (beta-alanyl-3-methyl histidine)
* All of the above a di-peptides
- Hemoglobin
68
Why did it take a long time to determine that Histidine is an essential AA?
It is hard to become deficient in it because it is found in large amounts of muscle and hemoglobin.
69
What is the name of the following methods that is:
Based on the concept that amino acids in excess of amounts needed for protein synthesis are oxidized by the body
Direct amino acid oxidation (DAAO) method
70
Direct amino acid oxidation (DAAO) method
In this method, the oxidation rate of an amino acid is measured as graded (ie, increasing) dietary intakes of that amino acid are consumed.
71
What are the stable isotopes used for the DAAO methods?
13C-Phenylalanine and 13C-Leucine
-The carbon that is labeled is that of the carboxyl group: -13COOH
72
In the DAAO methods how is the lelvel of oxidation measured?
-By feeding an isotopically labeled amino acids and then calculating the amount of labeled carbon dioxide exhaled by the subjects
The inflection (break point) in the oxidation curve represents the physiological requirement
73
In the DAAO method the level of oxidation with increasing intake is plotted on a _______
graph
74
In the DAAO methods, the inflection in the oxidation curve represents the __________ requirement?
Physiological
75
In the DAAO method, The inflection in the oxidation curve represents the physiological requirement is also known as the ___________
Break point
76
Where is a tracer (i.e. carbon 13) placed on an AA?
Carboxyl group
77
In the DAAO method:
If the body oxidizes the AA, then the carbon exhaled as _____.
CO2 via the breathe
Thus, we can determine how much of that AA was oxidized
78
The breakpoint indicated the _________
requirement
79
DAAO
f an AA that is tagged is low in the diet, then oxidation levels will remain low. When there is extra of the AA in the diet then there will be a lot of oxidation
80
What is the following method described to determine AA requirements?
Based on the hypothesis that the partition of any indispensable amino acid between oxidation and protein synthesis is sensitive to the level of the most limiting amino acid in the diet.
When an indispensable amino acid is limiting for protein synthesis, then all other amino acids are in excess and, therefore, must be oxidized
IAAO (Indicator AA oxidation_
81
Advantages of IAAO
- Does not require prior adaptation to diet
| - May be applied to a number of different amino acids
82
Indicator is the same, but the AA being tested is not the one that is labeled
IAAO
83
IAAO
Oxidation of the tagged AA is high. As we add the AA we want to test, the oxidation of the tagged AA will decrease.
84
DAAO and IAAO have the same inflection point, but there graphs are different.
_______/ = DAAO
\_______ = IAAO
85
An example of an indicator is
CO2
86
In IAAO, Indicators are located on which axis?
y-axis
87
In IAAO, the test AA is located on which axis?
x-axis
88
Hadaad Notes
In the IAAO technique, the amino acid that is being tested is different than the amino acid that is labeled. The amino acid that is being tested is called the “test amino acid” and the amino acid that is isotopically labeled is called the “indicator amino acid”
The level of oxidation of the “indicator amino acid” is measured by measuring 13C02 that is exhaled
The IAAO technique is based on the concept that when one essential amino acid is deficient for protein synthesis, then all other amino acids (including the indicator amino acid (usually 13Cphenylalanine) are in excess and are therefore oxidized.
Once the requirement is met for the amino acid being tested, there will be no further change in the oxidation of the indicator amino acid
The inflection point where the oxidation of the indicator amino acid stops decreasing and reaches a plateau is referred to as the “breakpoint”
The breakpoint indicates the requirement
89
Define Breakpoint
The inflection point where the oxidation of the indicator amino acid stops decreasing and reaches a plateau
90
Slide 26 Graph in Ppt.
Phenylalanine stays constant above the dietary requirement threonine, but as Threonine decreases the phenylalanine increases (becomes more oxidized)
This happens, because as we limit Threonine it also decreases our ability to synthesize protein and causes the excess amino acids to be oxidized (such as Phe)
91
24-hour indicator amino acid oxidation and balance (24h-IAAO and 24h-IAAB)
This method uses intravenous isotope infusion for 24 hours and involved collection of breath and blood samples for measurement of both (1) oxidation, and (2) plasma enrichment of the isotope
92
What two things does the 24h-IAAO and 24h-IAAB measure?
- oxidation
| - plasma enrichment of the isotope
93
Amino acid balance calculated as the difference between intake and oxidation at different time points.
What method is this?
24h-IAAO and 24h-IAAB
94
24h-IAAO
24 hour Indicator Amino Acid Oxidation
95
24h-IAAB
24 hour Indicator Amino Acid Balance
96
True or False:
Indispensable amino acid requirements determined by isotopic methods are higher than those of the US DRI or the FAO/WHO/UNU
True
97
True or False
The requirements for indispensable amino acids is also higher in infants and young children compared to adults
True
98
What does IDAA stand for?
Indispensable AA's
99
What its the percent IDAA for infants?
43%
100
Infants must have the highest quality of protein containing the essential AA's (IDAA)
True
101
In regards to IDAA's both quality and _______ are important.
Amount (quantity)
102
Indispensable AA's are also known as
Essential AA's
-Unable to be made in the body
