Nutrition 120 midterm 1 notes PDF

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Nutrition 120 midterm 1 notes Introduction to food guides and the nutrients How do we describe our diet? 1. In terms of food 2. In terms of nutrients (DRI) Food guides: Canada over time  Evolved over time with growing knowledge  Vegetables and fruit; grain products; milk and alternatives; meat and alternatives  Items at the bottom of food guide are most recommended/healthiest version Recommended number of food guide servings per day (adults) Vegetables and fruit  19-50 - females 7-8 - males 8-10  51+ - females 7 - males 7 grain products  19-50 - females 6-7 - males 8  51+ - females 6 - males 7 milk and alternatives  19-50 - females 2 - males 2  51+ - females 3 - males 3 meat and alternatives  19-50 - females 2 - males 3  51+ - females 2 - males 3 Directive statements

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suggests the healthiest choice of each food group fibre is what tells you you’re full If you’re thirsty, drink water

American food guide  Separates fruit and vegetables  My plate: shows portions on plate of how much of each category Mediterranean diet pyramid  Great way to eat  Bottom is activities (physical activity and slow down eating together etc.), all “plants” are grouped together including grains, fish and seafood are own category (lower risk of heart disease, cancer, etc.), includes drinking water, top level includes sweets Lacto-ovo-vegetarian: eats milk, eggs, vegetables The nutrients: 1. Carbohydrate 2. Fat 3. Protein - Top three (macronutrients, gram qualities per day) are what give us calories (calories from all of them) 4. Vitamins 5. Minerals - 4 and 5 are micronutrients (milligram: mg, microgram: mcg per day) 6. dietary fibre - can’t break fibre down What are “essential” nutrients?  Nutrients we can’t make ourselves/can’t make enough of to meet our needs  Essential Carbohydrates - Glucose (all carbs can be broken down to make glucose)  Essential Fat - Linolenic acid - -linolenic acid  essential protein - 9 essential amino acids (11 non-essential, can make yourself) - 9 essential amino acids: leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, histidine  essential vitamins - all vitamins are essential (except vitamin D, depends on where you live geographically)  essential minerals - all minerals are essential

“fate”, “risk” and “disease mitigation”  point to best suggestion for causation of these diseases  cancer can be genetic (10%)  30-40% contributed to dietary choices over one’s lifetime  mitigation: process or result of making something less severe EWCFG (eating well with Canada’s food guide) and DRI (dietary reference intake) values 1. food based: a) EWCFG (2007)  3 factors always included in the food guide over the years - balance/proportion: follow food guide and follow proportion sizes - variety: ensures we get all of our nutrients, improves appetite, can potentially dilute out any bad aspects of food - moderation: portion distortion (orange juice container), how much we should be eating in one sitting b) EWCFG: resource for educators/communicators  Food record assignment 2. Nutrient-based: DRI’s (dietary reference intakes) background/purpose:  EAR: estimated average requirements - Population statistic - Amount of a nutrient that meets the needs of half of your population  RDA: recommended dietary allowance - Calculated from the EAR value - Average daily nutrient amount that covers the needs of almost all healthy people in that population  AI: adequate intake value - When you don’t know the EAR, and can’t set your RDA, use AI value instead (set generously; extra to meet need of people) - Average daily nutrient amount that appears to cover the needs of all healthy people in that population  UL: tolerable upper intake level (upper limit) - Maximum amount of a nutrient that appears safe for most healthy people in that population - Above UL: increase risk of adverse effects (ex. Toxicity) How do we describe our nutrient intake? 1. Absolute amounts ingested per day - Mg, g, g, NE (niacin equivalents), RAE (retinol activity equivalents, from vitamin A) 2. As a percentage of total energy intake - Energy: Kcal (kilocalories) - Carb, protein, fat, alcohol

The “Atwater Factors” (do practice questions on BB)  Nutrient: 1g carb - Energy provided/gram (Kcal): 4 Kcal (17KJ)  Nutrient: 1g protein - Energy provided/gram (Kcal): 4 Kcal (17KJ)  Nutrient: 1g fat - Energy provided/gram (Kcal): 9 Kcal (38 KJ)  Nutrient: 1g alcohol - Energy provided/gram (Kcal): 7 Kcal (30 KJ) Example 1: 1000 calories = 1 Kcal = 1 Cal Examples 2: what gives you more Kcal? 10g fat, or 10g protein? - 10g fat x 9 Kcal/g = 90 Kcal - 10g protein x 4 Kcal/g = 40 Kcal Example 3: meal that provides 1620 Kcal. There were 60g of fat in that meal. Fat comprises what percent of the total Kcal in that meal? - Get grams into calories: 60g fat x 9 Kcal/g = 540 Kcal from fat - 540 Kcal  1620 Kcal x 100 = 33% Trends in Macronutrient intake: the past 50 years  current goals (sept 2002), as % of total Kcal (AMDR) - protein: 10-35 - fat: 20-35 - carbohydrate: 45-65  cut fat (heart problems), replaced with sugar Eating habits of Canadians  many Canadians eat more fat than recommended  many of our calories come from “other foods” (don’t fit in to any food group)  over a quarter of sources of fat is coming from “other foods” Canadian eating patterns: trends 1. Canadians have lowered fat intake as % of Kcal - Now eating 200-300 Kcal/day (more than in the 1960s) - 25% of total Kcal intake and 27% of total fat intake come from food category “other” - Daily calorie intake has been increasing 2. a) Daily energy intake over time b) Adult body weight over time 3. A large proportion of population is not eating minimum number of food guide servings (FGS) from any of the four food groups in EWCFG

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Main concerns: missing out on Ca, Fe, Zn, folate (dark green leafy vegetables), and overall dietary fibre (found in plants) a) Chronic disease b) If low intake of some things, what are we eating too much of? (salt, sugar, saturated and trans fat) c) Fertility issues (sperm production, overweight/underweight

BMI (body mass index) chart  BMI = wt(kg)  ht(m)^2 Health risk classification according to body mass index (BMI)  Risk of developing health problems: -  18.5 (underweight) increased - 18.5 – 24.9 (healthy weight) least - 25.0 – 29.9 (overweight) Examples of nutrient functions in the body Function Nutrient Energy Carbohydrate

Lipid

Protein

Structure

Lipid

Protein

Minerals

Regulation

Lipid

Protein

Example Glucose is a carbohydrate that provides energy to body cells Fat is the most plentiful source of stored fuel in the body Protein consumed in excess of protein needs will be used for energy Lipids are the principal component of the membranes that surround each cell Protein in connective tissue holds bones together and holds muscles to bones. Protein in muscles defines their shape Calcium and phosphorus are minerals that harden teeth and bones Estrogen is a lipid hormone that helps regulate the female reproductive cycle Leptin is a protein that helps

Carbohydrate

Water

Vitamins Minerals

regulate the size of body fat stores Sugar chains attached to proteins circulating in the blood signal whether the protein should remain in the blood or be removed by the liver Water in sweat helps cool the body to regulate body temperature B vitamins regulate the use of macronutrients for energy Sodium is a mineral that helps regulate blood volume

Canadian eating patterns: trends  why have overweight/obesity become epidemic? a) Kcal intake has increased (200 to 300 extra calories/day) b) Significant drop in physical activity levels since the 1960’s c) “toxic food environment” (Obesigenic environment, encourages weight gain) - convenient, cheap, like familiar foods, high calorie and fat foods, minimally nutritious foods Portion distortion  increase in portion sizes (40 years ago to today) - soft drinks 62% - French fries 57% - Cheeseburgers 24% How well can you estimate portion sizes? 1. How many FGS (food guide servings) of grain products in a 12-inch sub bun? - 6 2. About how many servings of meat and alternatives are in a meat patty of a quarter pound burger? - 2  Nauru has 71.1% of adults are obese Fat: where do I find it?  Name some high fat foods: - Avocado, coconut, French fries, onion rings - nuts, salmon, mackerel, meat with skin - cheese, cream/sour cream

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croissants muffins chips, oils, butter, margarine

Are potatoes a high-fat food?  Baked potato (plain) - Grams of fat: minimal  Baked potato with butter (1 tbsp.) - Grams of fat: 11 grams  Baked potato with butter and sour cream - Grams of fat: 13 grams  Mashed with milk and butter (whole milk, 3.25%) - Grams of fat: 9 grams  French fries - Grams of fat: 8 to 22 grams  Hash browns - Grams of fat: 23 grams What is Fat?  Most important form in food/nutrition: Triglyceride (TG) - Over 98% of all fat we consume is in this form - Glycerol backbone, attached are three fatty acids  Two important aspects of fatty acids: 1. chain length of fatty acid - 2-4 carbons: short chain fatty acids - 6-10/12 carbons: medium chain fatty acids - 14 and above carbons: long chain fatty acids (majority of fats we consume) 2. Degree of saturation - “Full” of hydrogen Formation of triglyceride (TG): condensation reaction (releases water and creates ester bonds) Types of fatty acids: 1. saturated fatty acid: palmitic acid - methyl or omega end, acid group where it’s attached to glycerol backbone (full of hydrogen, 16) - 18 carbons, no double bonds, 16:0 - found in meat, found in coconut oil 2. monounsaturated (most common MUFA) fatty acid: oleic acid (omega 9) - methyl or omega end, acid group where it’s attached to glycerol backbone (full of hydrogen, 18) - 18 carbons, 1 double bond (position of double bond is at carbon number 9), 18:1n-9 - found in avocado, olives and olive oil 3. polyunsaturated (PUFA) fatty acid: linoleic acid (omega-6)

methyl or omega end, acid group where it’s attached to glycerol backbone (full of hydrogen, 18) - 18 carbons, 2 double bonds (position of double bonds are at carbon number 6 and carbon number 9), 18:2n-6 and 18:2w-6 - double bonds always separated by three carbons 4. polyunsaturated (PUFA) fatty acid: alpha-linolenic acid (omega-3) - methyl or omega end, acid group where it’s attached to glycerol backbone (full of hydrogen, 18) - 18 carbons, 3 double bonds (position double bonds are at carbon number 3, 6 and 9), 18:3n-3 - found in flax, nuts (particularly walnuts) -

Summary of fatty acid types Type of fatty acid Location of 1st double bond Example Omega-6 6th carbon Linoleic acid rd Omega-3 3 carbon Alpha-linolenic acid  fish oils: - 20:5n-3 = EPA eicosapentaenoic acid - 22:6n-3 = DHA docosahexaenoic acid  all naturally-occurring fats are a combination of fatty acids oil, butter, margarine: glycerol backbone, 18:0 18:2n-6 16:0 are the three fatty acids review questions  what do you know about? (2 essential acids) - 18:2n-6 – 18 carbons, 2 double bonds, first double bond is at carbon 6 from methyl end, omega-6 (linoleic acid), found in any plant based oils - 18:3n-3 – 18 carbons, 3 double bonds, first double bond is at carbon 3 from methyl end, (alpha linolenic acid), found in flax, walnuts  legumes: pinto beans, peanut, chickpeas, lentils tree nuts: almond, walnut, pecans Essential fatty acid deficiency: symptoms  scaly dermatitis (inflammation of the skin)  impaired growth  excess loss of water through the skin Role of fat in the diet 1. source of energy (Kcal, the most concentrated for with 9Kcal/gram) 2. provides essential fatty acids (linoleic acid and alpha-linolenic acid) 3. carries fat-soluble vitamins (A, D, E, and K) 4. palatability (how things taste or feel in the mouth, “mouthful”), “fat potentiates full flavour and aroma of food” - the more liquid a fat is at room temperature, the healthier it is (butter vs. oil)

Role of fat in the body 1. insulation, keeps the body warm 2. protection (essential) - skeleton and vital organs (heart, kidneys, etc.) 3. energy reserve – store of energy or calories in adipose (fat) cells - can reduce levels of fat only by “burning”/oxidizing stored fat 4. precursors for other biomolecules: (starting point for making something else) - eicosanoids (biological messengers/cell signals, prostaglandins), made from F.A. - phospholipids, made from F.A. - bile acids (fat digestion), made from cholesterol - steroid hormones (estrogen, testosterone), made from cholesterol 

cholesterol is NOT an essential nutrient (body can make it from scratch)

Food processing and trans fat  hydrogenation: how trans-fat is made, manufacturing process  purposes: - transform oil (liquid fat) into harder, spreadable fat (bread and baking; hard margarine, hydrogenated vegetable “oil”, shortening) - to enhance shelf life of all processed foods (in general, hard fats (less double bonds) don’t go rancid as fast as an oil etc.)  result/end product? - Hard margarine, hydrogenated vegetable “oil” (shortening) Fat hydrogenation: the process  Veg oil (liquid)  Apply H2 (gas), heat and pressure  Creates fully hydrogenated fat, trans fat (hard like butter) 19:1t, don’t know where the transformation occurred  Creates partially hydrogenated vegetable “oil”, 18:2n-6, 18:0, 18:1t (all spreadable, margarine) Trans fatty acids (TFA’s)  What are they? - Category/group of fatty acids types formed in hydrogenation process  Compare: - Most naturally-occurring fatty acids have “cis” double bonds 18:1n-9, 18:2n-6, introduces a “kink” in its structure naturally - Hydrogenation produces “trans” double bonds 180-degree twist around double bond, “linear” like 18:0 Food sources of TFA’s  Minority: dairy foods, less than 6% of TFA intake

Conjugated linoleic acids (CLA): cluster of trans fats formed naturally in rumen of cow (accenic acid) Majority: processed foods containing: - Margarine - Hydrogenated/partially hydrogenated vegetable “oil” - shortening Some examples: peanut butter, cookies, chips, crackers, mixes, frozen waffles, pastries, batters (deep fried) -

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Healthiest order of fats/oils: liquid oils, non-hydrogenated margarines, butter, shortening/hydrogenated margarines - Now: non-hydrogenated margarines “inter-esterification” Trans fats: concerns/actions  Significant contributor to coronary heart disease (CHD)  Canadians had one of the highest intakes of TFA in the world  Canadian Trans Fat Task force: findings and recommendations (2006-2009)  What are the next steps? - Trans fats are now banned in Canada Review questions: 1. What is 18:1t? - 18 carbons, whole range of double bonds created through hydrogenation process (don’t know where they all are) 2. what does cis and trans mean? - Cis means ions are on the same side (repel each other because like charges, causes a bend), trans means ions are on opposite sides Fats: digestion, absorption and metabolism  Digestion: enzymatic breakdown of food constituents to smallest absorbable unit - Glucose (carbohydrates), amino acids (proteins), fatty acids (fats)  Absorption: transfer of digested food components across absorptive surface of GIT (gastrointestinal tract) into vascular (blood) or lymphatic system  Metabolism: various pathways nutrients take following digestion and absorption to be stored or used to make other biomolecules  Read chapter 3.5 (lymphatic versus hepatic-portal/vascular circulation), figure 3.2 How is fat digested and absorbed?  Small intestine: 1. Triglycerides in food enter small intestine 2. liver produces bile, bile acids are stored in Gall bladder - bile acids enter small intestine, disperse fat into smaller droplets (emulsification) 3. pancreas releases lipase enzymes (enzymes that break down fat, act like scissors that chop off fatty acids off of triglyceride separating the fatty acids and glycerol

4. 5. -

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6. 7.

backbones), can lead to partially digested triglycerides called monoglyceride with one fatty acid still attached lipase enzymes enter small intestine bile acids, fat soluble portions of fatty acids facing in, backbone of monoglyceride’s facing out formation of micelle (fat attracted to interior of bubble, water surrounds exterior of bubble) bile acids (x), are known as emulsifiers, keep fat emulsified (mixed in with water) inside intestine is called lumen, intestinal wall is called mucosa fatty acids and monoglyceride’s absorbed into intestinal wall (mucosa); absorption if fatty acids are less than or equal to 12 carbons in length (considered water soluble), absorbed into portal vein (vascular) with other water-soluble nutrients and components (amino acids, glucose, etc.) and heads to the liver first, then the rest of the body if fatty acid is greater than or equal to 14 carbons in length, reformation of triglycerides in mucosal cells (intestinal wall), then become packaged into Chylomicrons (A, D, E, K, cholesterol) chylomicron absorbed into lymphatic system which eventually reaches bloodstream at the neck (thoracic duct) then to the rest of the body (bypasses liver) bile acids (x) reabsorbed/recycled back to liver then to be released to do it all again (Entero-hepatic-circulation)

Bile acids: summary 1. made from cholesterol (we can make all the bile acids we need, created in liver) 2. required for: - emulsification of fat - formation of micelles 3. amount required each day is much larger than the amount synthesized - reabsorption is very efficient (recycled 3-5x/meal, very small % is lost in feces) Practical application: want to maintain healthy blood cholesterol levels?  C = dietary cholesterol, X = bile acids, O = soluble fibre (high amounts in oatmeal, citrus fruits, fruit pulp, inside of legumes; not skin)  Small intestine: food enters small intestine (C, O, liver and gall bladder supply X) - Cholesterol absorbed as part of chylomicron (lymphatics to blood stream to high blood cholesterol which increases the risk of heart disease) - X undergoes enterohepatic circulation to recycle/reuse bile acids - C-O and X-O exits by fecal elimination - With soluble fibre: (helps maintain healthy blood cholesterol levels) 1. Less dietary cholesterol absorbed 2. Less bile acids recycled. Forces liver to make more bile acids from cholesterol (make cholesterol from scratch or easier, to take up ready source of cholesterol from the blood in order to make more bile acids; result is blood cholesterol levels will drop)

Fat metabolism: the lipoproteins  Transport molecule (job is to transport fat)  Exists only in blood/lymph (not found in fat)  All contain triglycerides, cholesterol, protein (serve as “ID cards”), phospholipids  Small intestine to 1. chylomicron (biggest of lipoprotein) - triglyceride rich - “drop off” fatty acids at adipose tissue/fat tissue (store fatty acids) - becomes smaller and becomes chylomicron remnant - docks at liver (specific protein to specific spot on liver) - liver takes excess amino acids/glucose etc. and changes it to fat 2. liver releases VLDL (packed on fat to chylomicron) - triglyceride rich - “drop off” fatty acids at adipose tissue/fat tissue (store fatty acids) - IDL 3. LDL (low density lipoprotein; “bad cholesterol”) - Cholesterol rich (if LDL levels are elevated it’s bad) - LDL delivers cholesterol to all body cells (they all need cholesterol) - Returns to liver (LDL receptor, specific protein to specific spot on liver) 4. HDL (high density lipoprotein) - Protein rich - “reverse cholesterol transport” - picks up excess cholesterol and takes it to the liver for disposal Review questions: 1. which of the following is a product of fat digestion? - Free fatty acids 2. A micelle contains: - Bile acids and monoglyceride’s 3. The lipoprotein most enriched in protein is: - HDL (high density lipoprotein) 4. Eating a diet rich in ___ may help keep both blood TC (total cholesterol) and LDL within healthy levels and reduce CHD risk - Soluble fibre Figure 5.14, Wiley ...