Chapter 5 Outline Lipids Essential Energy Supplying Nutrients 1 Lipids are insoluble in water a 3 types found in foods body cells and tissues triglycerides phospholipids and sterols b Fats are the lipid content of diets and foods 2 Triglycerides 3 fatty acids 1 glycerol molecule a Chain length short medium or long i Carboxyl end COOH alpha carbon alpha first ii Methyl end CH3 omega carbon omega last b Saturation i Saturated fatty acids hydrogen atoms surrounding every carbon in the chain ii Monounsaturated 1 double bond lack one hydrogen atom iii Polyunsaturated more than 1 double bond c Shape determined by the saturation of the carbon chains i Saturated shape packed tightly together solid at room temp animal fats butter and lard ii Unsaturated shape don t stake well together liquid at room temp hydrogen d Hydrogenation hydrogen atoms are added to unsaturated fatty acids atoms can be arranged in different positions 1 Cis same side of the carbon chain 2 Trans opposite sides of the chain i Make oils more solid and more saturated ii Create trans fatty acids iii Reduce oxidation resist rancidity iv Increased risk of cardiovascular disease e Essential fatty acids cannot be made by the body and must be obtained from food i Linoleic acid omega 6 fatty acid found in vegetable and nut oils 1 Fish and fish oil EPA DHA 2 Reduce risk of heart disease regulate prostaglandins PGs and thromboxanes TXs 3 Reduce inflammatory responses blood clotting and plasma triglycerides ii Alpha linoleic acid omega 3 fatty acid found in vegetables soy flaxseeds walnuts 3 Phospholipids glycerol backbone two fatty acids and phosphate soluble in water transport fat in bloodstream manufactured in our bodies 4 Sterols contain multiple rings of carbon atoms made in our body not necessary in diet a Plant sterols block the absorption of dietary cholesterol b Cholesterol c Sex hormones vitamin D bile 5 Fatty acids are classified by a Carbon chain length b Saturation level c Shape 6 Digestion of Fats begins in small intestine a CCK and secretin gallbladder contractions release bile i Bile emulsifies fat into small droplets produced by liver and stored in the gallbladder ii 7 Absorption of Fats meal b Pancreatic enzymes break fat into 2 fatty acids and a monoglyceride Lipoprotein transport lipids for absorption a b Chylomicron lipoprotein produced in cells of small intestine to transport lipids from a i Composed of fatty acids surrounded by phospholipids and proteins ii Soluble in water travel through lymphatic system transferred to the bloodstream c Triglycerides are disassembled by lipoprotein lipase before they enter cell body i They can be used immediately for energy ii Used to make lipid containing compounds iii Stored in muscle and adipose tissues d Short and medium chain fatty acids are NOT arranged into chylomicrons and are absorbed more quickly 8 The Roles of Fat a 9 kcal per gram major fuel at rest endurance exercise stored energy essential fatty acids fat soluble vitamins regulates cell function maintains membrane protects the body provides flavors and textures of foods helps us feel satiated c Active people may need more energy from carbs and can reduce their fat intake to 20 9 How Much Fat a AMDR for fat is 20 35 of calories b Lower saturates and trans fatty acid intake i Lower risk of heart disease 25 of total calories d DRI set for essential fatty acids i Linoleic acid AMDR of 5 10 of energy ii Alpha linolenic acid 0 6 1 2 of energy iii 5 1 to 10 1 ratio of linolenic alpha linolenic acid e Saturated fat 10 of energy i Trans fats should be reduced to the absolute minimum 10 Food sources of Fats a Visible fats fats we add to food butter cream mayo dressings b Invisible fats hidden within foods naturally or added during processing baked goods dairy meat and fast foods c Beneficial fats omega 3 fatty acids may be low in diets fish walnuts soy canola flax d Switch to more healthful fats without increasing total fat intake i Use canola or olive oil in place of butter or margarine e Fat replacers chips cakes cookies may cause GI side effects in large amounts 11 Cardiovascular disease a Dysfunction of the heart or blood vessels that can result in heart attack or stroke b Risks overweight physical inactivity smoking high blood pressure diabetes mellitus inflammation c Dietary fats increase blood lipids d Highly saturated and trans fat intakes increases blood cholesterol e Omega 3 fatty acids decrease inflammation and blood triglycerides f Blood lipids i Chylomicrons exogenous fats transports dietary fats into blood and tissues mostly triglycerides ii VLDL endogenous fats sources of fats that the body produces on its own transports lipids to various tissues of the body iii LDL bad cholesterol transports cholesterol to the cells of the body 50 cholesterol protein iv HDL good cholesterol transport cholesterol from tissues back to the liver 50 g Diets high in saturated fats decrease the removal of LDLs from the body h Diets high in trans fats can raise blood levels of LDL cholesterol as much as saturated fat i Abundant in hydrogenated vegetable oils margarine baked goods and fried foods i Dietary intake i Less than 300 mg of cholesterol per day ii Trans fats reduce to absolute minimum iii Increase omega 3 fatty acids iv Dietary fiber 20 30g per day v Folate 400 ug per day j
View Full Document
Unlocking...