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NUTR 3210 Study Guide - Midterm Guide: Glut2, Palatability, Plant CellPremium

14 pages110 viewsWinter 2014

Department
Nutrition
Course Code
NUTR 3210
Professor
James B Kirkland
Study Guide
Midterm

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NUTR 3210 Lecture Notes
Introduction to Nutrition
Nutrition: the processes by which the organism ingests, digests, absorbs, transports, utilizes and excretes food
substances.
Essential nutrient: chemical that is required for metabolism, but that cannot be synthesized or cannot be
synthesized rapidly enough to meet the needs of an organism for one or more physiological functions.
- Nutrients are essential to human diet if:
1. Removing the nutrient from the diet causes a decline in some aspect of health.
2. Replacing the nutrient in the diet will cure the deficiency symptoms observed from removing it (have to
reverse it because some progressive conditions cannot be reversed).
Nutritional deficiencies: a person’s nutrient intake consistently falls below the recommended requirement.
- Deficiency in iron, folate and/or vitamin B12 = anemia.
- Deficiency in vitamin D = do not absorb calcium from diet efficiently.
- Deficiency in thiamine (vitamin B1) = Beriberi.
- Deficiency in vitamin C = scurvy.
Nutritional requirement: provide optimal intake to prevent disease.
- Range of nutrient intakes required by individuals to achieve same end point of growth, storage or health
- Dietary Reference Intakes (DRIs) include EAR, RDA and UL.
- Estimated Average Requirement (EAR): meets the needs of ~50% of the population.
- Recommended Dietary Allowance (RDA): EAR + two standard deviations, meets the needs of ~97.5%
in each life-stage and sex group.
- Tolerable Upper Intake Level (UL): highest, safe intake.
- Some nutrients do not have an RDA< but have an AI.
- Adequate Intake (AI): do not have enough confidence in normal distribution so they just say x amount
of nutrient is safe.
- 2.5% will not be satisfied in requirements (risk toxicity to other individuals if requirement is too high to
satisfy these 2.5% though).
Outcomes from Minnesota Starvation Experiment:
- Lost ~2.5lb/week
- Decrease in enthusiasm, increase of impatience and irritability
- Decrease of cold tolerance
- Dizzy, loss of coordination
- Decrease in sex drive
- Two months to two years for full recovery
Nutritious diet has four characteristics:
1. Adequate – enough calories, essential nutrients and fibre to meet requirements.
2. Moderate - Do not over consume calories or individual foods.
3. Balanced – focus on nutrient dense foods.
4. Varied – wide selection of foods to receive balanced nutrients and avoid food toxicities.
Studying Nutrition
- Cell culture models
oin vitro
oGreat control of variables
oQuestionable human applicability
- Animal models
oAllow invasive approaches in whole animal models (in vivo)
oHuman applicability
- Epidemiological
oProspective (do not change behaviour) versus intervention (follow protocol)
oSurveys do not prove causality
oRandomized clinical trials (RCT) have ethical burdens
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oDifficulties with genetics, lifestyle, cultural habits, etc.
Nutrient Classes
- Macronutrients: building blocks, energy substrates, etc.
oCarbohydrates and fibre (organic substance, carbon-containing)
oLipid (organic)
oProtein (organic)
- Micronutrients: diffuse functions, metabolic regulators, energy cofactors, hormones, etc.
oVitamins (organic)
oMinerals (inorganic)
oWater (inorganic)
Body Composition
- 55.65% water
- 20-25% lipid
- 15% protein
- 2% vitamins and minerals
- 0.5% carbohydrate
Metabolism
- Catabolism is the break down to create energy, degrades tissue structures
- Anabolism is creating tissue structures, use of energy
- Energy balance and the formation/breakdown of macromolecules are key components of metabolism
- Maintain ATP, blood glucose, lean mass, brain tissue fat, etc. over a life span
Water
- First essential nutrient
- Adult human intake: 2-2.5kg/day
oCompared to carbohydrates (250-350g/d), fat (60-80g/d) and protein (50-80g/d)
- Functions: solvent, lubricant, temperature regulation, catabolism (hydrolysis)
- 10% of water is from hydrolysis of energy substrates
- Start to lose physiological function at 2% body weight loss of water
- Water toxicity
oWater > kidney’s ability to process each hour
~0.9L/hr
oHyponatremia: a metabolic condition in which there is not enough sodium in the body fluids
outside the cell
oNeed sodium gradient
Food / Feeds Composition, Proximate Analysis
Food: eaten by humans
Feed: eaten by agricultural animals
Food analysis: development, application and study of analytical methods for characterizing foods and their
constituents
- Allow consumer to make informed decisions
- Eliminate economic fraud by enforcing government regulations
- Ensure consistent food composition for human/companion animal health
- Encourage optimal animal growth/profitability in agriculture industry
Moisture = Water
- Determining water content is important because:
oTropical environments, lactating animals need food water
oHigh water foods spoil quicker
oDry food lack palatability
oHighly variable food component
oDry matter (agriculture: always remove water) vs. wet weight basis (human: too confusion to
remove water from nutrient analysis)
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moisture=weight loss
wet weight of sample ×100
dry matter=100moisture
- Potential Errors
oOther volatiles removed
oShort chain fatty acids will dry off and leave
oAlcohols
Ether Extract = Crude Fat
- Ether is a strong solvent, non-polar
- Extracts fat
- Quantify important dietary lipids such as triglycerides (TG),
phospholipids (PL), cholesterol and fatty acids
crude fat =weight of crude fat
wet weight of sample ×100
- Potential Errors
oPlant products include chlorophyll, carotenoids, resins, waxes
oPL extraction not complete (slightly polar, not easily extracted by ether)
oPoor definition of subclasses, need GC analysis to get PUFA (polyunsaturated fatty acids),
MUFA (monounsaturated fatty acids), saturates, trans fats
Ash = Mineral Content
Ash=weight of ash
wet weight of sample ×100
- Potential Errors
oVolatile minerals
oSome loss of Fe, Cu, Zn
oAtomic Absorption Spectroscopy: sodium
Kjeldahl Analysis to Determine Nitrogen
- Assume all food nitrogen is in the form of amino acids/protein and protein is 16% nitrogen by weight
- Three main steps:
1. Digestion – a homogenous sample mixed with sulfuric acid (nitrogen into ammonia) volatile
2. Distillation – separating the ammonia
3. Titration – quantifying the amount of ammonia with a standard solution
crude protein=Nsample ×6.25
wet weight of sample ×100
- Get 6.25 from 100% protein ÷ 16% nitrogen = 6.25
- Potential errors:
oAssumes all proteins have 16% nitrogen (actual range is 13-19%)
oOther forms of nitrogen includes nitrates, nitrites, urea, nucleic acids, etc. which are interpreted
as protein
Crude Fibre = Fibre
crude fibre=
(
weight of ash+crude fibre
)
weight of ash
wet weight of sample ×100
- Potential errors:
oUnderestimate fibre because of hemicellulose, pectin and hydrocolloids
oCrude fibre does not equal dietary fibre
Crude fibre includes lignin and cellulose
Dietary fibre includes cellulose, hemicellulose, pectin, hydrocolloids and lignin
Nitrogen Free Extract (NFE) = Digestible Carbohydrate (CHO)
- Mainly starches and sugars
NFE=100( moisture+crude fat +ash+crude protein+crude fibre)
- Potential errors:
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