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Midterm

3210 Midterm: NUTR 3210; Course Study Notes for the Midterm
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by OneClass51262 , Winter 2014
14 Pages
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Winter 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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Description
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 o in vitro o Great control of variables o Questionable human applicability - Animal models o Allow invasive approaches in whole animal models (in vivo) o Human applicability - Epidemiological o Prospective (do not change behaviour) versus intervention (follow protocol) o Surveys do not prove causality o Randomized clinical trials (RCT) have ethical burdens o Difficulties with genetics, lifestyle, cultural habits, etc. Nutrient Classes - Macronutrients: building blocks, energy substrates, etc. o Carbohydrates and fibre (organic substance, carbon-containing) o Lipid (organic) o Protein (organic) - Micronutrients: diffuse functions, metabolic regulators, energy cofactors, hormones, etc. o Vitamins (organic) o Minerals (inorganic) o Water (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 o Compared 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 o Water > kidney’s ability to process each hour  ~0.9L/hr o Hyponatremia: a metabolic condition in which there is not enough sodium in the body fluids outside the cell o Need 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: o Tropical environments, lactating animals need food water o High water foods spoil quicker o Dry food lack palatability o Highly variable food component o Dry matter (agriculture: always remove water) vs. wet weight basis (human: too confusion to remove water from nutrient analysis) - Potential Errors o Other volatiles removed o Short chain fatty acids will dry off and leave o Alcohols 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 - Potential Errors o Plant products include chlorophyll, carotenoids, resins, waxes o PL extraction not complete (slightly polar, not easily extracted by ether) o Poor definition of subclasses, need GC analysis to get PUFA (polyunsaturated fatty acids), MUFA (monounsaturated fatty acids), saturates, trans fats Ash = Mineral Content - Potential Errors o Volatile minerals o Some loss of Fe, Cu, Zn o Atomic 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 - Get 6.25 from 100% protein ÷ 16% nitrogen = 6.25 - Potential errors: o Assumes all proteins have 16% nitrogen (actual range is 13-19%) o Other forms of nitrogen includes nitrates, nitrites, urea, nucleic acids, etc. which are interpreted as protein Crude Fibre = Fibre - Potential errors: o Underestimate fibre because of hemicellulose, pectin and hydrocolloids o Crude 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 - Potential errors: o Error from each method o Does not differentiate between starch and sugar General Comments on Proximate Analysis - No information on digestibility - No information on specific amino acids, minerals, lipids, carbohydrates - Still used in food labeling and animal feed analysis - Provided the basis for developing more advanced analyses Dietary fibre: non-digestible complex CHO and structural part of plants - Insoluble: cellulose, lignin, hemicellulose o Remains largely intact through intestinal tract (does not dissolve in water) o About 2/3 of fibre in foods o Helps move food bulk through intestine o Participates in control of intestinal pH which can benefit microbiota o Regular bowel movements o Helps toxic components pass through the intestine more quickly o Reduces risk of diverticulitis, colon cancer o Provides small amount of energy through VFA production - Soluble: pectins, gums, mucilages o Forms gel, ferments in colon to produce VFAs (does dissolve in water) o Binds with fatty acids, bile acids and lipohilic toxins, dioxins o Slows down stomach emptying, which slows the absorption of sugar (i.e. lowers glycemic index), decreases peak blood glucose o Reduces cholesterol absorption by interacting with bile acids o Provides energy and maintains colon and microbiota health through the support of fermentation and release of VFAs  VFAs include acetic (2c), propionic (3c) and butyric (4c) Food/Feeds Composition 1) Van Soest Method (animal feeds) - Detergent Fibre Analysis - Quantifies fermentable and non-fermentable CHO for agricultural applications - Differentiates between insoluble fibre components such as cellulose and hemicellulose (at least partially fermentable especially by ruminants), and lignin (indigestible) - Poorly differentiates between sugars, starches, cell solubles 2) Southgate Method (human food labeling) - Provides quantification of sugars, starch and total fibre - Useful for human nutrition and food labeling, but less so for agricultural applications because not enough information on fermentability - Does not differentiate fibre components (like soluble vs. insoluble) Digestive Systems - Digestion: chemical, enzymatic, mechanical breakdown of the complete food matrix - Absorption: digested molecules pass through the mucosal cells into the blood stream - Different systems: o Simple system (without caecum) o Simple system (with functional caecum) o Ruminant system o Avian system - Gastrointestinal (GI) tract o Many variations across species o Mouth, esophagus, stomach, small intestine, large intestine, caecum, rectum o GI tract = digestive tract ≠digestive system o Digestive system = GI tract + associated organs (liver, pancreas, gallbladder) 1. Simple System (e.g. human, pig, cat, dog) - Monogastric - Non-functional caecum (appendix + cecum, little fermentation or VFA production) - Suited for nutrient dense, low fibre diet Digestion - Oral cavity: chewed, mix with saliva, α-amylase and lingual lipase are released - Stomach: gastric glands secrete gastric juice (water, electrolytes, enzymes, HCl), acidic pH, becomes chyme (proteins are denatured, party degraded) - Small intestine (duodenum, jejunum, ileum): main site of digestion and absorption, intestinal motility (secretions controlled by the enteric nervous system), chyme acidity neutralized by pancreatic juice, digestion of food by pancreatic juice and bile acids o Until fully digested, impeding waves send undigested food backwards to small intestine o Large surface area  Kerckring folds  Villi and crypts  Crypts have cell division  Villi go up, crypts go down  Cells divide in here, go up and replenish the surface of the villis  Microvilli  Brush border  Site of absorption of most nutrients  Just a membrane bilayer  Nutrient transport  Driven by solubility, concentration gradient, molecular size  ATP used to pump Na+ because it is against gradient  Diffusion only occurs with lipophilic molecules, most have transporters to increase rate - Large intestine (also called colon): fermentation, production of short chain fatty acids (SCFA or VFA), water absorption and electrolytes (Na+, Cl-) o Ferment undigested fibre, resistant starch, protein, etc. o CO fermentation generates lactate and VFA (acetic, propionic, butyric) o VFA affect colon health (especially butyric), energy and blood glucose (propionic can be regenerated into glucose) 2. Simple system with functional caecum (e.g. horse, rabbit, hamster) - Hind-gut fermentation - Functional caecum, high VFA production - Suited for a diet with large amounts of forage, high fibre, low nutrient density - Bacteria can breakdown fibers to sugars and VFA - Produce various vitamins - Up to 70% of energy from VFA - Coprophagy: eating fecal matter (seen in rabbits and rats) to obtain bacterial protein, vitamins, increase mineral availability, but exposes to parasites 3. Ruminant system (e.g. cattle, sheep, goats) - Multiple system - Fore-gut fermentation - Large stomach divided into four sections (rumen, reticulum, omasum, abomasum) - Highly suited for animals that eat a high amount of roughages Digestion - Reticulum o Regurgitates large food particles for further chewing (ruminating) cud o Honeycomb appearance in order to capture particles o Traps foreign materials o Region of microbial fermentation - Rumen o Largest section of the stomach o Rumen papillae (increases surface area for absorption) o Food is mixed and partially broken down and stored temporarily o Rich in bacteria o 60-80% of energy by VFA - Omasum o Reabsorption of water and some electrolytes o Filters large particles - Abomasum o “True” stomach, similar to that of monogastric animals o Digestive enzymes secreted from gastric glands (HCl, mucin, pepsinogen, lipase, etc.) - Fermentation takes place before entering the intestine, may destroy high quality components of the diet - Nutrients produced are available for subsequent digestion and absorption (without coprophagy) - Vitamin synthesis, mineral availability, synthesis of essential amino acids, non-protein nitrogen utilization, but there is the destruction of available CHO, protein and major heat production 4. Avian system (e.g. chicken, turkey, etc.) - Beaks and claws are important for breaking up foods into smaller pieces the birds can swallow - Rapid digestion (can starve in short period of time) - No teeth because they are heavy and birds need to fly - Very little fermentation Digestion - Crop o Enlarged area of the esophagus o Serves as temporary storage location for food o Food is softened, often regurgitated to feed offspring - Two-chamber stomach o Glandular portion = proventriculus (gastric enzymes and HCl are secreted) o Muscular portion = gizzard (grind and digest tough foods, use small stones as “teeth”) - Small intestine o Similar functionality as other systems - Ceca o Minor site of bacterial fermentation o Absorption of water, trace minerals - Large intestine o Very short, serves predominantly to connect the small intestine and cloaca o Storage of undigested material, water absorption - Cloaca o Where digestive, urinary and reproductive systems meet Digestibility - Measure of the fraction of a specific nutrient or of energy that is extracted by the GI tract - Calculated from amount of nutrient in the diet and the amount appearing in the feces - Represents a combination of nutrient release from the food matrix, microbial fermentation and absorption - Important in calculating inputs in an agricultural setting - Important in humans for bioavailability Total Collection Method - Allow individual to adapt to diet over a 7-21 day period - Isolate individual for quantitative analyses - Measure intake over a 3-10 day period - Collect and weigh all feces - Analyze for nutrient of interest - No units, between 0-1 - Limitations o Metabolic cages = anxious animals o Labour intensive Indicator Method (or Marker Technique) - Requires a marker o Internal (a natural component of the feed) o External (a component added to the feed) o Non-absorbable, must not alter GI function, mixes with food, easy accurate measurement - Adapt animal to test diet (includes marker) - Collect a feed and fecal sample - Analyze each for marker and nutrient of interest - Less labor intensive, just need a small sample of feed and feces - Can be done on free or captive wild animals (less stress) Apparent Digestibility - May underestimate true digestibility - Endogenous secretions from epithelial cells (fatty acids and protein), bacterial growth in gut, digestive enzymes (protein secretion) - Makes digestibility look lower than what it really is True Digestibility - Steps o Perform digestibility study using test diet o Switch to diet containing none of the nutrient of interest o Analyze feces after previous diet has cleared o Subtract level of nutrient in feces of animals fed the zero nutrient diet from the test diet  Usually done with an indicator - Not necessarily true - Mostly corrected for endogenous losses - Physiology may be altered by zero nutrient diet Factors Affecting Digestibility - Feed intake, particle size, chemical composition, climate, age Energy - Energy metabolism: the sum of all chemical reactions involved in obtaining and utilizing food energy - Cellular source of energy ATP o Muscles, ion gradient, anabolic pathway, active transport o Supplied by nutrients in the diet (mostly macronutrients) - Energy value of a food: calorie (cal) a measure of heat - kcal = 1000 calories = 1 Calorie (1 Cal) - Energy Balance o Energy In – food and drink o Energy Out – metabolic and cellular function o Positive Energy Balance: weight gain/obesity, infertility, cardiovascular disease, insulin resistance, growth and development o Negative Energy Balance: weight loss, infection - Energy Intake: consumption of macronutrients (proteins/amino acids, fats and carbohydrates) for essential roles in building cells and tissues, sooner or later we also oxidize these molecules via glycolysis and the TCA cycle to produce metabolizable energy (ME) - Calorimetry = measurement of heat production o Use heat as an indicator of the amount of ene
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