Midterm Flashcards
1
Q
What is Nutrition?
A
The science of food
- nutrients and substances in food
- their action/interaction/balance in relation to health and disease
- processes by which organisms ingest/digest/absorb/transport/utilize and excrete food substances
2
Q
Essential nutrients
A
A chemical that is required for metabolism but cannot be synthesized efficiently, or at all, in order to meet needs of organism
3
Q
Nutrients are essential if…
A
- removing the nutrient causes a deficiency/decline in health
- putting the nutrient back into the diet fixes the problem and returns health to normal
4
Q
Nutritional deficiency
A
Occurs when a person’s nutrient intake falls below recommended requirement
5
Q
Anaemia
A
Deficiency in iron, folate or B12
6
Q
Rickets
A
Deficiency in vitamin D
7
Q
Beriberi
A
Deficiency in thiamine (B1)
8
Q
Scurvy
A
Vitamin C deficiency
9
Q
Deficiency and nutritional requirements
A
They do not equal each other
- deficiency is the prevention of disease
- nutritional requirement ensures optimal health
10
Q
What is the significance of WWI and food rations?
A
Prompted our understanding of nutritional requirements
11
Q
What were early limitations to our understanding of nutritional requirements?
A
age, gender, body size and physical activity were not considered
12
Q
A nutritious diet must be what four things?
A
adequate, moderate, balanced, varied
13
Q
Adequate diet
A
provides enough Calories, essential nutrients and fibre to keep you healthy
14
Q
Moderate diet
A
means not eating excessive Calories or eating more than recommended of one food group
15
Q
Balanced diet
A
making sure you eat nutrient dense foods
16
Q
Varied diet
A
eating a wide assortment of foods to get necessary nutrients
17
Q
What is a good model for understanding human lipid/cholesterol metabolism?
A
PIGS
18
Q
Organic nutrients?
A
Contain carbon:
- carbohydrates
- lipid
- protein
- vitamins
19
Q
Inorganic nutrients
A
- minerals
- water
20
Q
Body water composition
A
60%
21
Q
Body lipid composition
A
20-25%
22
Q
Body protein composition
A
15%
23
Q
Body vitamin/mineral composition
A
2%
24
Q
Body carbohydrate composition
A
0.5%
25
Anabolic
Building blocks
| - for example insulin
26
Catabolic
Breaking down
| - glucagon
27
Water intake by adult humans
2-2.5 kg/day
28
Functions of water
- lubricant
- solvent
- regulates temperature
- catabolsim (hydrolysis)
29
What is water toxicity?
When water intake levels are greater than kidney's ability to filter (~.9L/hour)
30
Hyponatremia
water/electrolyte imbalance
- metabolic condition
- not enough sodium in blood so cells swell
31
Food analysis
The development, application, and study of analytical methods for characterizing foods and their constituents
32
Why is food analysis important?
- because it gives information about food
- allows producers to make foods that are safe and nutritious
- allows consumers to make informed decisions
33
What does government regulation of food analysis do?
- ensures quality of foods
- ensures food industry makes safe foods with high quality
- regulates fair competition between companies
- eliminates economic fraud
34
What does quality control do?
- ensures food composition doesn't change
| - characterize raw materials
35
Nutrient density
refers to the amount of nutrients compared to caloric content
- not all foods are created equal...
36
Feed sample analysis includes:
- moisture
- ether extract
- ASH
- nitrogen
- crude fibre
37
Why is determining moisture content in feed important?
- water is weight and weight is money
- moisture content influences storage conditions
- moisture dilutes energy and nutrients in food
- moisture is required for optimum intake and performance
38
% moisture =
(weight loss/wet weight) x 100%
39
% dry matter =
100 - %moisture
40
Potential limitations when calculating % moisture in feed sample?
- drying can remove other volatile compounds such as short chain fatty acids and minerals which causes a slight underestimate of dry weight
41
Human food labeling is based on?
wet weight
42
Agricultural industry more interested in?
composition of dry matter
43
Ether extract
Method for determining crude fat
44
% crude fat =
(weight of crude fat/wet weight of sample) x 100%
45
Potential limitations when calculating % crude fat in feed sample?
Overestimate from other things being soluble in ether extract
- chlorophyll, resins, waxes in plants
46
Proximate analysis
A partitioning of both nutrients and non-nutirents into categories based on common chemical properties
47
What is the ash fraction?
contains all the mineral elements jumbled together
| - allows for calculation of nitrogen-free extract from dry matter and provides estimate of contamination
48
Why is it important to measure ash content?
- nutritional labeling
- quality and taste of food
- microbiological stability
- nutritional requirements
- processing
49
% ash =
(weight of ash/wet weight of sample) x 100%
50
Potential limitations when calculating % ash in feed sample?
- volatile minerals may be lost when burning residue
| - no information about individual minerals
51
Kjeldahl analysis
Method for determining crude protein in feed sample
52
What assumptions are made for Kjeldahl analysis?
- all nitrogen is in protein
| - all protein contains 16% nitrogen
53
What are the 3 main steps to Kjeldahl analysis?
1. Digestion - A homogenous sample mixed with sulfuric acid (converts nitrogen to ammonia)
2. Distillation – separating the ammonia (remove)
3. Titration – quantifying the amount of ammonia with a standard solution (measure how much ammonia in initial sample)
54
% crude protein =
[(N in sample x 6.25)/wet weight of sample] x 100%
55
Potential limitations with Kjeldahl analysis?
- assumes all protein contains 16% nitrogen (actual range is ~13-19%)
- other sources of nitrogen may be considered crude protein (overestimates)
56
Step 5. Crude Fibre
Two boiling processes simulate the pH conditions of the digestive tract, acidic in the stomach and alkaline in the small intestine
- left with fibre we don't absorb
- estimate of insoluble carbohydrates
57
% crude fibre =
{[(weight of ASH+crude fibre) - (weight of ASH)]/wet weight of sample} x 100%
58
Potential limitations with crude fibre analysis?
- some fibre content underestimated because certain types may be partly soluble in acids and bases so they are lost during process
- we are unable to distinguish which dietary fibres are in there
59
Nitrogen free extract = ??
Digestible carbohydrate
| - estimates starch and sugar content
60
% NFE =
100 - (% moisture + % crude fat + % ASH + % crude protein + % crude fibre)
61
Potential limitations with % NFE?
Accumulates all the errors that exist for other components
62
Proximate analysis gives no information on what?
- digestibility of food/feed
| - specific amino acids, minerals, lipids or carbohydrates
63
Proximate analysis going after
estimates
| - used as basis for food labelling and animal feed analyses
64
Dietary fibre
Non-digestible complex CHO
| - structural part of plants
65
Insoluble fibre
- remains intact
- ensures things move through in good manner
- does not dissolve in water
66
Soluble fibre
- solubilizes in intestinal tract forming gel like matrix
- holds on to things
- limits carbohydrate absorption
- dissolves in water
67
Methods for determining dietary fibre in food composition
- Van Soest Method
| - Southgate Method
68
Van Soest Method for Fibre Analysis in Feeds
- determines fermentable and non-fermentable CHO
- differentiates between insoluble fibres
- poorly differentiates sugars, starches, & cell solubles
69
Southgate Method
- provides information about sugars, starch and soluble fibre
- useful for human nutrition and food labeling
- does not differentiate between fibre components adequately, so this method is not used for agricultural applications
70
GI tract = _______ but not _______
Digestive tract; digestive system
71
Digestive system
Digestive tract plus all the other associated organs
72
GI tract
cylindrical tube all the way from mouth down to rectum
73
Digestibility
Does the organism have the molecular machinery to digest all carbohydrates?
- if yes it is digestible
- if no it is not
74
Solubility
What consumed carbohydrates go into solution in small intestine?
75
Fermentability
Do gut bacteria have molecular machinery to break down dietary carbohydrates? And create by-products available for our use?
76
Simple system without caecum found in?
- human
- pig
- cat
- dog
77
Key features of a simple system without caecum
- mono gastric
- non-functional caecum (may be present but serves no purpose)
- suited for nutrient dense, low fibre diet
78
How long is human digestive tract?
~16 feet
79
How does digestion work?
- oral cavity
- stomach
- small intestine
- large intestine
80
Simple system with functional caecum found in?
- horse
- rabbit
- hamster
81
Key features of a simple system with caecum
- pseudo-ruminant
- caecum plays important role serving as bacterial fermentation vat
- suited for a diet with large amounts of fodder
82
How long is horses digestive tract?
~100 feet
83
What is the purpose of a functional caecum?
- enormous hindgut (20-30L capacity) with bacteria
- obtains 70% energy from SCFA
- produces B vitamins
- animals are very dependent on this production of energy to survive
84
Multiple System: Ruminant found in what animals?
- cattle
- sheep
- goats
85
Key features of a ruminant system?
- large stomach divided into 4 sections
| - system highly suited for animals that eat a high quantity of fodder
86
Why the difference in digestive systems between cows and horses?
Based on evolutionary adaptation over time
Horse – relies on speed (doesn’t want stomach full of food)
Cows – exist as herds
87
How does ruminant system digestion work?
- reticulum
- rumen
- omasum
- abomasum
88
Pros of a ruminant system
- vitamin synthesis (e.g., B Vitamins, Vitamin K)
| - non-protein nitrogen utilization for making protein
89
Cons of a ruminant system
- carbohydrates degraded into gases and lost
| - heat production
90
Avian system?
Found in chicken, turkey
91
Key features of avian system?
- beaks and claws are important for breaking up foods into smaller pieces
- rapid digestion
92
Crop
Important in avian digestion
| - serves as short term food storage
93
How does avian digestion work?
- crop
- two chamber stomach
- small intestine
- ceca
- large intestine
- cloaca
94
Measure of digestibility
The fraction of specific nutrient extracted by GI tract
| - calculated from amount of nutrient in diet and amount appearing in feces
95
Why is measuring digestibility important?
It prevents deficiency and ensures essential nutrients are available to the organism
96
How is digestibility measured?
Total collection method
- allow the animal to adapt to the diet over a 7-21 day period
- isolate animal for quantitative analyses
- measure intake over a 3-10 day period
- collect and weigh all feces
- analyze for nutrient of interest
97
Apparent Digestibility Coefficient =
Total collection method:
(Total intake - total feces)/total intake
Indicator method:
(A-B)/A
where A = ratio of nutrient/marker in feed
and B = ratio of nutrient/marker in feces
98
Limitations of total collection method
- accuracy in measuring food intake.
- metabolic cages creates anxiety in animals
- labour intensive
- animals confined in costly equipment
- not feasible for captive wild animals
99
Indicator method to measure digestibility
- adapt animal to test diet (marker included)
- collect a feed and fecal sample
- analyze samples for marker and nutrient of interest relative to indicator
100
Indicator method requires marker. Explain
```
Requires an internal and external marker
- non-absorbable
- must not affect or be affected by GIT
- mix easily with food
- accurately and easily measured
EX: ferric oxide, chromic oxide, silica, lignin
```
101
Advantages of indicator method?
- less labour intensive
| - better for wild animals
102
Apparent digestibility _____ true digestibility
underestimate
103
What aren't considered when estimating apparent digestibility?
- endogenous secretions
- bacterial growth in gut
- digestive enzymes
104
How is true digestibility measured?
- perform study using a TEST diet
- switch to diet containing none of the nutrient of interest
- analyze feces after test diet is cleared
- subtract level of nutrient in feces of animals fed the ZERO NUTRIENT DIET from the TEST diet
105
True digestibility coefficient =
[A - (B - C)]/A
where A = ratio of nutrient/marker in TEST DIET
B = ratio of nutrient/marker in feces
and C = ratio of nutrient/marker in feces after zero nutrient diet
106
What are some factors that influence digestibility?
- feed intake
- particle size
- chemical composition
- climate
- age
107
Food Calorie
Energy required to raise the temperature of 1 kg (1L) of water by 1 deg. C
108
Antoine Lavoisier
Compared heat produced by a guinea pig with production of CO2
- ice calorimeter
109
Justin Liebig
Recognized that protein, carbohydrates and fats are oxidized
110
Max Rubner
Measured energy values of certain foods to determine caloric values
111
Calorimetry
Measure of heat production
| - amount of heat in food being broken down by metabolic fuels in body
112
Bomb calorimetry
Works on principles of direct calorimetry
- dry and weigh sample (~1g), and place in enclosed chamber (the ‘bomb’) with oxygen
- ignite sample
- heat released is absorbed by water and measured
113
Potential errors with bomb calorimetry
- overestimates energy because we don't digest food the same way
- doesn't account for energy needed to digest and absorb
114
Physiological fuel values
Essentially useful energy (take into account incomplete digestion)
- 4, 9, 4 (CHO, fat, protein)
115
Why does fat provide more kcal per gram vs. CHO or protein?
The chemical basis of CHO, fat, and protein has an important impact
- more oxygen in structure = less energy produced
116
Factors that affect the heat of combustion of fatty acids?
- chain length
| - degree of unsaturation
117
Longer chain length releases ____ energy
more
118
The more double bonds the ____ energy is released
less
119
Heat increment of feeding (HIF) - thermic effect of food
Energy used for the digestion, absorption, distribution & storage of dietary nutrients
- 5-30% of energy expenditure
- used to determine Net Energy
- taken into account to determine basal metabolic rate
120
Net Energy
Supports basal metabolism, physical activity, growth, pregnancy, etc
= Available Energy – HIF
121
Primary components to energy expenditure
- BMR
- HIF
- Physical activity expenditure
- Thermoregulation
122
Specific requirements for measuring BMR
- shortly after walking
- post absorptive state
- lying down
- completely relaxed
- comfortable room temperature
123
BMR =
kcal/24 hours
124
What tissues are most reflective of the BMR?
Muscle and bone
125
Factors that affect BMR
- genetics
- age
- gender
- exercise and body tissue proportions
- temperatures
126
Can you use body fat % to calculate BMR?
The Katch-Mcardle BMR equation
| - if you precisely measure body fat %, you can have a more accurate measure of BMR
127
BMR vs. RER
Both are a measure of metabolic rate but different testing conditions:
- conditions are more tightly controlled when measuring BMR
- RER experimental conditions aren't controlled as tightly sometimes introducing error
128
Direct calorimetry
Measures the heat a person generates; total heat loss
- very impractical
- expensive
129
Indirect Calorimetry
Energy-releasing reactions in the body depend on the use of oxygen
- estimate using oxygen consumption, carbon dioxide production, urinary nitrogen loss
130
Limitations to human calorimetry?
Methods cannot account for anaerobic processes
| - don’t push someone too far that they are into anaerobic zone
131
Respiratory quotient
Ratio of metabolic gas exchange
| - provides information about energy expenditure and biological substrate being oxidized
132
RQ =
CO2 / O2
133
Assumptions when using RQ to determine energy expenditure
- only CHO and fat are metabolized.
- no synthesis is taking place at the same time as breakdown
- amount of CO2 exhaled = amount of CO2 produced by tissues
