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nutr mid 2 .docx

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NUTR 1010
Laura E Forbes

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10/22/2012 11:51:00 PM  Fats and Lipids  What are Lipids?  A large group of molecules that are not soluble in water  What makes thing soluble in water? o Water + Glucose (sharing electrons)  A large group are that are not soluble o What makes this soluble in water?  Water + fatty acids (repel sharing electrons)  Diverse class of molecules that are insoluble in water  Fates are one type of lipid  Lipids do not dissolve in water  What lipids do we Eat?  Lipids in the diet consist of o Triglycerides: (solid fats & oils) with glycerol + 3 fatty acids  95% of dietary lipid  usually what were talking about when we say “fat” o Phospholipids: (eg. Lecithin)  Make up cell membrane o Sterols  Cholesterol is the main one  Triglycerides  We eat triglycerides and store our body fat as triglycerides  Made of o 1 glycerol molecular “glycerol backbone” o 3 fatty acid molecules  long hydrophobic chains of carbon and hydrogen  Fatty Acids  Different fatty acids give triglycerides different properties  Fatty acids can be different o Lengths- of their carbon chain  Short: fewer than 6 carbon atoms  Medium: 6-12 carbons  Long-chain: 14 or more carbon  Fatty Acid Length Affect  How it is digested and processed in the body  Its function in the body  Its properties before/when you eat it  Fatty Acids with Different Saturation (the way we classify fatty acids)  Saturated (SFA)= NO double bond (have hydrogen atoms surrounding every carbon in the chain)  Unsaturated= 1 or more double bond o Monounsaturated (MUFA)= 1 double bonds (lack 2 hydrogen atoms at one carbon; one double bond) o Polyunsaturated (PUFA)= 2 or more double bonds (lack hydrogen atoms at multiple carbons; one double bond)  Saturation Affects  Solid at room temperature (eg. Animal fats, butter, lard, tropical oils, coconut oils)  How they are processed in the body  The effect on health  Monounsaturated Fats  Olive oil, canola  Polyunsaturated Fats  Canola, safflower, corn oil, fish, nuts and seeds o Liquid at room temp o More likely to spoil  Shape of Triglyceride  Determined by the saturation of the carbon chains and by the number & types of double bonds  Cis= hydrogen molecules on the same side of the carbon chain (almost ALL are in the Cis shape  Trans= hydrogen moecules on opposite side of the carbon chain  Most fatty acids have Cis bonds  Trans fats are on nutrition labels o Trans fat act in the same way as saturated fats  Where is that double bond?  The bond closest to the end of the fatty acid o Omega (ω) end o This last bond affects how your body uses the fat  Omega -3 fatty acids= doube bond at the third carbon from the end  Omega-6 fatty acids= double bond at the 6 thcarbon from the end  Trans Fats  Naturally in: o Beef, meat, milk, cheese, cows, goats, sheep  Hydrogenated fats: (man made trans fat) o Shortening, hard margarine, chips, peanut butter o Coverts liquid fats (oils) into a more solid form o Often creates trans fatty acids  Naming your Fatty Acids  Fatty acids are given common names and numerical notations  Example: 18:2 ω-3 o 18 = number of carbon o 2 = number of double bonds o ω-3 = where the last bond is on the chain  Phospholipids  Less then 5% of our diet  Are composed of o Glycerol backbone o 2 fatty acids o Phosphate  Are soluble in water  Are manufactured in our bodies so they are not required in our diet  Part of all cell membranes  Used by the food industry as emulsifiers, because they are both fat and water soluble  Lecithin supplements not needed o Broken down in intestines o Excess causes G1 discomfort  Sterols  Sterols: o A large group of hydrophobic compounds  Found in plants and animals  Most common in animals = cholesterol o lipids containing multiple rings of carbon atoms o Are essential components of cell membranes and many hormones o Are manufactured in our bodies and therefor are not essential components of our diet o Cholesterol found only in animal products o Some cholesterol comes from food, but liver makes most o Excess cholesterol in blood get deposited on inside artery walls-plaque- atherosclerosis- risk factor for heart disease & stroke  Fat Digestion  Mouth- chewing and lingual lipase  Stomach- churning into small droplets gastric lipase  Small intestine o Bile emulsifies fats into small droplets  Micelles o Pancreatic Lipases breaks fatty acids off of glycerol  Free fatty acids and mono-glycerides  Fat Absorption  Chylomicrons are absorbed by cells of the small intestine, then they o Travel through the lymphatic system o Are transferred to the bloodstream and continue to liver  Short and medium chain fatty acids are absorbed more quickly since they are not arranged into chylomicrons  Fistful lipids make up the membrane  When you eat fat they’re in from of triglycerides  What is a Lipoprotein  Packages your body puts together  It has fat in there  Can be transported around  Hydrophilic ends on outside  Hydrophilic ends on inside  Types of lipoproteins  Chylomicrons o Made in the cells of the small intestine o Carries dietary fat to the liver and the rest of the body for burning or storage o Live= control station  Other types of lipoproteins o Very low density lipoproteins (VLDL) o Low density lipoproteins (LDL) “bad cholesterol” o High density lipoproteins (HDL) “good cholesterol”  Transport fats to and from the liver  Why do I need fat?  Energy/ Energy storage (biggest difference between fat+carbs  1g of fat provides how much energy? o 9kcal/gram  high fat foods have high energy density  your cells burn fat as rest and during exercise  triglycerides stored in adipose tissue (fat cells)  stored fat gives your energy reserves o keeps you from starving  for the heart and for protection o provides insulation o protects bones, joints, and organs o very important for making and protecting the brain and spinal cord (protects neurons)  For cell structure o Phospholipids make up cell membranes o Cholesterol keep membranes fluid (animals only)  Provides essential fatty acids o Essential means your body cant make them  There are fats we need for things like o Blood clotting o Blood pressure regulation o As a building block to make other fats  Did you Know?  In healthy women, fat makes up 25-35% of their body weight  In healthy men, fat makes up 10-22% their body weight  Essential Fatty Acids  Linolenic acid o 18:2 ω-6  (18 carbons, 2 double bonds, omega-6) o Alpha (α) Linoleic acid  18:3 ω-3 (18 carbons, 3 double bonds, omega 3)  How to get Essential fats?  Linolenic Acid (oils, margarine, nuts, and seeds  Alpha-Linpleic Acid (canola, flax, soy, fatty fish, omega eggs)  How much fat do I need?  Als based on how much essential fats you need to keep clotting etc. under control  For a balanced diet use the AMDR for fat o 20-35% of calories from fat  How Do Canadains do? In 2004, statistics Canada found that ¼ of Canadains had more then 35% of their calories coming from fat  Are there recommendations for different types of fats?  The AMDR’s states hat for cholesterol. Saturated fat and trans fat: o As low as possible while consuming a nutritionally adequate diet  Cardiovascular Disease (CVD)  Disease of the heart, arteries + veins  Can result in heart disease, high blood pressure, heart attacks, strokes  29% of all deaths in Canada are from CVD  CVD costs the Canadian economy more then 20.9 billion every year  Main cause = Atherosclerosis o Plaque builds up around the inside of the artery o It can clog an artery by breaking off  Dysfunction of the heart or blood vessels  the type of fat in our diet can contribute to or protect against CD  RISK FACTORS o Age, gender, family history of CVD o Being overweight/obese o Being physically inactive o Smoking o High blood pressure o Diabetes o Diet- fat intake  Fats and Heart Disease  Saturated and trans fats increase risk of heart disease  MUFA and omega 3 polyunsaturated fats decrease risk  They effect the type and amount of lipoproteins, triglycerides and cholesterol in the blood  Lipoproteins  Carriers of lipids in the blood  Chylomicrons carry fat from the intestine to the body and the liver  Liver makes very low density lipoproteins o L packed with fay = the body o Become low density lipoprotein o The liver makes high density lipoproteins  Doctors measures blood lipids to look assess heart disease risk  When they measure o LDL- cholesterol, they measure the # of LDL particles o HDL- cholesterol, they measure the # of HDL particles o Triglycerides, they measure the # of VLDL particles o LDL:HDL ratio measures which “dump trucks” are winning  Cholesterol  We eat cholesterol in animal foods (meat, milk, eggs)  Out body makes cholesterol  For most people, eating more cholesterol is not associated with higher blood levels o Not a main dietary target for reducing heart disease  Omega 3 Polyunsaturated Fats  Are healthy fats  Eating omega 3s o Help babies brains develop o Help prevent mental decline with aging o Decrease risk of CVD  Improve blood lipid levels  Decreases blood clotting  Alpha-linoleic acids  Long chain omega 3 fats are the most heart healthy  They are found in fish o Fatty fish, salmon, trout, herring, mackerel  2 types oflong chain omega 3s  eicosapentaenoic acid (EPA) - EPD:20:5  docosahexaenoic acid (DHA) – DHA:22:5  Getting enough Omega 3s  Eating well with canadas food guide recommends eatint at least 2 servings of fish per week  Omega 3 food- milk, yogurt, eggs  Supplements – fish oil, fish oil capsules, microencapsulated fish oil  Eating too much omega 3 fats can lead to hernorrhaginy  Low fat products  Thickener- usually carbohydrates  Moistening- fruit puress (adds carbohydrates)  Milk or egg protein for creamy texture  Fat substitutes  Replacements similar in structure to fats, but aren’t absorbed by the body o Olestra- may cause rectal leakage 10/22/2012 11:51:00 PM  Protein and Amino Acids  What are proteins?  Large molecules with many functions  Our body contains thousands of different proteins  Contain carbon, hydrogen, oxygen and nitrogen  Are made of long strings of amino acids  Large molecules made of amino acids  Contain carbon, hydrogen, oxygen, nitrogen  Primary source of nitrogen in our diet  20 different amino acids are used to make proteins  There are 20 amino acids  9 of these are essential o meaning; our body cant make them and you have to eat them o cannot be produced by our bodies o must be obtained from food  11 are non-essential o still important, but our body can make them through transamination o can be make by our bodies o made by transferring amino groups (transamination)  Getting essential AAs is important  If there aren’t enough of all the essential AAs, your body cant make proteins  Complete proteins have all the essential AAs  Incomplete proteins are missing some AAs  Complementary protein = 2 sources of protein that together contain all the AAs  Complete proteins  Animal foods – meat, fish, poultry, eggs, milk  Very few plants – soy and quinoa  9 essential amino acids  considered a “high quality” protein  if one or more AA missing, then protein synthesis stops; nitrogen removed from AA and excreted  protein from animal foods are complete, but proteins from plant foods are incomplete  Incomplete proteins  Proteins found in grains are low in isoleucine and lysine  Beans are low in methionine and tryptophan  Does not contain all essential amino acids in sufficient amounts  Not sufficient for growth and health  Considered a “low quality” protein  Complementary proteins  Eating beans with grains provides all the amino acids  Protein sources (foods) that together supply all 9 essential amino acids (beans and rice)  Mutual Supplementation  Using 2 incomplete proteins together to make a complete protein  How are proteins made?  Your body keeps a pool of amino acids  Your DNA tells your body how to string amino acids together to make proteins o Transcription- RNA message o Translation- creating the protein from the RNA message  Proteins are long chains of amino acids  Amino acids are joined to each other by peptide bonds  The structure of each protein is dictated by the DNA of a gene  During Translation amino acids are attached with peptide bonds  Peptide Terminology  Peptide = amino acids attached using a peptide bond o 2 amino acids = dipeptide o 3 amino acids = tripeptide o a few amino acids = oligopeptide o a lot of amino acids = polypeptide (one protein may contain several polypeptide chains)  Protein Shape  Different amino acids in the chain are attracted to each other o Complex folding of the molecule  Folding determines the shape and shape determines functions  Genetic mutations can cause proteins that don’t work  Example: sickle cell anemia  One AA difference changes shape. Function or hemoglobin  AA in a protein determines shape: o Positive or negative charge- can repel each other, causing protein chain to twist; make the molecule hydrophilic (attracted to water) o Neutral electric change- make the molecule hydrophobic (repelled by water)  Denatured protein = heat, acid, alcohol destabilize o proteins uncoil and lose shape  protein in food  AA units body puts AA together to make protein  Protein Digestion  Mouth- mechanical digestion  Stomach o Hydrochloric acid breaks down protein structure (denatures) Acid denature protein (gets unfolded) o Hydrochloric acid activates pepsin. Pepsin breaks long protein into smaller chunks and single AAs o Pepsin: an enzyme that breaks down proteins into short polypeptides and amino acids  Small intestine o Proteases break down remaining proteins into (smaller polypeptides) oligopeptides, tipeptides, dipeptides and amino acids o Peptidases (complete the digestion of proteins into single amino acids) break oligopeptides, tripeptides, dipeptides into amino acides o Free amino acids, di- and tripeptides can be absorbed into the intestinal cells o The cells beak di- and tripeptides into AAs  What Do Proteins do?  Cell growth and maintenance o Many cell structures contain lots of protein  Muscle,skin,bones,organs,blood cells  All need to be replaced- as cells go away, protein does to o We recyle- old cells are broken down and we save the amino acids of the proteins to use again o Without protein the calcium in our bones wouldn’t be able to do anything o All of our cells need proteins o What needs the most protein? – muscle cells, allows it to contract, without it we wouldn’t be able to do anything o Act as Enzymes and Hormones  Enzymes- allow chemical reactions to happen  Hormones- chemical signals in the body (every chemical reaction that happens requires enzymes)  Protein hormones include:  Growth hormone  Insulin  Prolactin (stimulates milk production (breast))  Gastrin (stimulates the stomach)  Leptin(has a role in satiety (if you feel full or not) and weight control) o Transport into and out of cells  Facilitated diffusion  Active transport o Transport in the blood  Albumin- transport nutrients such as calcium, zinc and vitamin B6  Lipoproteins (phospholipids + proteins transports lipids in the blood)  (protein transports let certain nutrients/molecules pass through the lipid layer) – Diagram o Maintains fluid balance- Albumin  Fluids are attracted to protein- diffusion  Balanced concentrations of protein are needed between the insides and outsides of cells and in the blood  If not – edema  Swelling of the feet (hard to pump blood lack up and pools in your feet – water in the blood) o Maintains electrolyte balance  Main electrolytes: sodium + potassium  Electrolyte balance is needed for muscle and nerve function – and fluid balance  Cells have sodium/potassium pumps made of protein to keep the balance o Acid base balance  Some proteins are good buffers  Blood too acidic or basic? Protein can help o Maintains your immune system  Antibodies are proteins that destroy invaders (bacteria, viruses, etc) o Proteins can provide energy  BUT your body prefers to use carbs & fat  If you get rid of the nitrogen you can  Burn the acid group for energy  Turn the acid group into fat – like this better  Turn the acid group into glucose (only some AAs)  The nitrogen comes off as ammonia which is TOXIC  Must get rid of it by peeing it out  How much protein is enough?  For adults the RDA is: 0.8g per kg body weight  Based on the amount of protein you need for maintaining ______________ o You have enough protein for making new cells. Hormones, enzymes etc  Proper protein intake depends on o Activity level o Age o Health status  Example: each day, a sedentary adult requires 0.8 grams protein per kg of body weight.  A 60kg(~130lbs) women needs 48g  Based on 0.8g per kg body weight  An 80kg (~180lbs) man needs 64g  Based on 0.8g per kg body weight  Do Some people need more?  YES o Children (0.95g/kg) and adolescents (0.85g/kg) o Athletes (1.2 to 3g kg) – need to replace cells more often because they are using their muscles o Hospital patients (as high as 2g/kg body weight) – to rebuild tissues o Vegetarians  Protein from gain products is less well digested and absorbed then from animal products  Doo Some people need less?  What if a person is overweight? o Does a 230kg person (~500lb) need 184g protein?  The equivalent of 7 servings of meats and alternatives TOO MUCH  NO o Use a healthy body weight for a person of their height  Canadians eat more than 0.8g/kg  Most people eat between 1g/kg 3g/kg  Most Canadians have protein intakes that meet the AMDR (10-35% of energy)  Is there such a thing as too much?  YES  High protein intakes (above 35% of kcals) is associated with high saturated fat intake o High blood LDL cholesterol levels  May contribute to bone loss with agin o Increase calcium excretion  Can increase risk of kidney disease o Kidneys work hard to get rid of nitrogen from extra amino acids  What happens to extra protein  The amino acid “pool” doesn’t store much protein  Extra amino acids are stripped of Nitrogen o Excreted in urine  Turned into sugars or fats to be burned for energy or to be stored (as fat)  How healthy is my protein  It depends on: o Complete/incomplete o Digestility of the protein  Meat,milk,eggs and beans have great digestibility  Grains, fruit and vegetable have poor digestibility (not as much protein) o Other nutrients found in the protein foods  Low in saturated fat,salt  High in fibre, iron, calcium, B vitamins  Omega 3 fats  If you don’t eat enough protein  You cant replace important proteins so some sacrifices are made o Your body breaks down muscle for amino acids o Immune system (wont be as strong) o Blood proteins, impaired nutrient transport, fluid balance  If not corrected, other functions are lost o Electrolyte balance, acid base balance – death o Never dysfunction o Organ dysfunction o Brain shut down  Marasmus  Severe protein, energy malnutrition  Low in protein, in calories, carbohydrates, fat, vitamins, minerals – EVERYTHING  Severe wasting- slowly starving to death  Skin and bones  Most common in young, impoverished children (6-16 months old)  Results in o Infections o Dehydration o Electrolyte imbalances o Heart failure  Marasmus in Canada is usually called Cachexia  Cachexia = wasting (skin and bones)  Most often happens in diseases o Cancer o Anorexia o AIDS o Elderly  Kwashiorkor  “the disease the first child gets when the second is born” o poor countries belief  common in children 1-3 years old in impoverished countries  severe protein deficiency  children are weaned from breast milk and are given a grain based pap (oatmeal watered down – starchy paste – little protein)  skinny legs and big stomach o big stomach caused by edema and fatty liver o low blood protein causes fluid imbalance o blood proteins cant transport fat  prone to infections and disease o immune system compromised o frequently die of infections, dehydration due to diarrhea  Marasmus and Kwashiorkor can be cured but  It has to be done carefully (could take months)  Relapse will happen if returned to the impoverished environment ($, long term solution or no solution at all)  Could suffer from long term effects of low nutrient intakes o Stunting o Slower brain development  Both marasmus and kwashiorkor = both wasting and edema  Closer look at vegetarianism  Many kinds o Lacto-ovo-pesco: vegetarian eats milk, eggs, and fish o Lacto-ovo: vegetarian eats milk and eggs o Lacto: vegetarian eats milk not eggs o Ovo: vegetarian eat eggs not milk o Vegan eats no food from animals  Why become vegetarian?  Religious, ethical and food safety reasons o Many religions don’t eat meat  Hinduism, buddism, some Christians (7 thday Adventists) o Ethical reasons  Belief that animal treatment is inhumane o Food safety  Eg. Mad cow disease  Ecological Reasons  Meat calories cost more than plant calories o In terms of water and energy o Especially grain fed cattle (time consuming)  Antibiotic use may contribute to “superbugs”  Greenhouse gases from cattle  Destroying forests for pastures  Transport of meat products  Health Reasons  Vegetarian diets are high in fiber, vitamins, minerals, low in saturated fat  Decreased risk for: o Cardiovascular disease o Obesity o Many cancers o Diabetes o Kidney disease  Challenges of a vegetarian Diet  Can be a challenge to get enough protein and iron o Careful dietary planning required o Incorporation of eggs and cheese o Complementary sources of protein o Enhance iron absorption  Avoid eating calcium and iron together  Eat iron foods with vitamins C  Extra challenge of Vegan diet  Vitamin B12- found exclusively in animal foods o Vegans must supplement with pills, injections or yeast extracts  Calcium and vitamin D- get them from milk alternatives, supplements  Iron- meat alternatives, whole grains and leafy greens 10/22/2012 11:51:00 PM  Antioxidants  What are antioxidants?  Chemicals that prevent oxidation o Also happens in your body  Chemicals that protect cells from damage from oxidation, including: o Vitamin E, Vitamin C, Beta-carotene, Vitamin A, Selenium o Structure of Atoms  Atoms= the smallest unit of mater  They are composed of  Nucleus- positively center portion of the atom  Electrons- negatively charged particles surrounding the nucleus  Oxidation  Molecules are composed of atoms  Du
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