Lipids Triglycerides Fats and oils Phospholipids Sterols Lecithin Cholesterol

Objectives After reading Chapter 4, class discussion and learning activities, you will be able to Identify types (classification) of lipids Describe the role of lipids in the body Discuss lipid digestion, absorption and transport Calculate calories from fat

Objectives Identify food sources of fats Discuss the health related effects of lipids Blood lipid profile Omega fatty acids Trans fatty acids Hydrogenation

Triglycerides p. 128 Fig 4-1 4

Triglycerides glycerol

Triglycerides glycerol + 3 fatty acids  triglyceride

Fatty Acids Length of fatty acid Degree of Saturation 18-24 carbons in length Degree of Saturation Saturated fatty-acid Monounsaturated fatty-acid Polyunsaturated fatty-acid p. 129

Fatty Acids Point of unsaturation Location of double bonds Omega number Omega-3 fatty acid Omega-6 fatty acid

Triglycerides Degree of saturation determines: Firmness Stability Oxidation Antioxidants

Rancidity Definition: Deterioration of fat; resulting in undesirable flavor/odor Flavor Reversion-soy oil; Cu, Fe Hydrolytic: Separation of glycerol from fatty acids Short chain fatty acids Butyric fatty acid; butter Oxidative: Loss of hydrogen in presence of air/heat Oxidation of double bonds Polyunsaturated fatty acids

Trans Fats Degree of unsaturation revisited Hydrogenation Cis vs. trans-fatty acids Trans fat occurs naturally in meat and dairy foods Conjugated linoleic in milk Possibly positive for heart health

p. 108 NRAEF p. 135-137 Fig 4-9

Phospholipids

Phospholipids Phospholipids in foods-Lecithin Roles of phospholipids Plasma membrane Emulsifiers

Phospholipids

Sterols Found in plants and animals Cholesterol is most abundant Found in animals only Found in every cell in man’s body Body makes ~700mg/day Dietary intake 200-400mg/day

Dietary Cholesterol

Sterols Roles of sterols Manufacture bile acids Make hormones Estrogen and testosterone Make adrenal hormones Make Vitamin D Maintain cell membranes

Fat Digestion Hydrolysis Triglycerides  monoglycerides, fatty acids, glycerol

Fat Digestion Mouth Stomach Melting Lingual Lipase Churning and mixing Gastric Lipase

Fat Digestion Small intestine Fat triggers the release of hormone Cholecystokinin (CCK) Gallbladder releases bile Bile emulsifies fat so it can be more fully digested Pancreatic lipase Intestinal lipase

Fat Digestion

Fat Digestion Enterohepatic circulation How bile travels through the body

Fat DigestionOverview

p.152 5-17

Lipid Transport Lipoproteins Chylomicrons VLDL = very-low-density lipoproteins LDL = low-density lipoproteins HDL = high-density lipoproteins

Lipid Transport

Lipid Transport Lipoproteins and health LDL: carries cholesterol from liver to the cells of the body High=Less healthy HDL: carries cholesterol from the cells back to the liver High=More healthy

Roles of Triglycerides Fat stores Energy Protection Insulation Provide essential fatty acids Insure efficient use of protein and carbohydrate

Essential Fatty Acids Linoleic acid and the omega-6 family Arachidonic acid Linolenic acid and the omega-3 family Alpha omega 3 fatty acids Marine omega 3 fatty acid EPA =eicosapentaenoic acid DHA = docosahexaenoic acid

Sources Essential Fatty Acids

Health Effects of Lipids Blood lipid profile Cholesterol=<200mg/dL LDL=<100 HDL=>60 TG=<150 Risks from saturated fats, trans fats, cholesterol Benefits from polyunsaturated fats monosaturated, omega-3

Health Effects of Lipids Risks from trans fats Alter blood cholesterol like saturated fats Raise LDL cholesterol Lower HDL cholesterol at high intakes Increase inflammation & insulin resistance AI = 5 gm/day Risks from cholesterol Not as implicated as saturated or trans fats Beware cholesterol sensitivity Limit intake <300 mg/day

Health Effects of Lipids Benefits from monounsaturated fats and polyunsaturated fats Olive oil (monounsaturated) Lowers LDL and total cholesterol Lowers blood clotting factors Lowers blood pressure Provides phytochemicals which act as antioxidants

Health Effects of Lipids Benefits from omega-3 fats Prevent arrhythmias Lower blood pressure Improve blood vessel function May ease inflammation Prevent repeat heart attack 1 gm supplement daily for 3 years Balance omega-6 and omega-3 intakes

How Dietary Fat Affects Blood Lipids Type of Fatty Acid Effects on Blood Lipids Saturated Polyunsaturated Monounsaturated Omega-3 Trans - G Total Cholesterol G LDL Cholesterol - H Total, LDL, HDL Cholesterol - H Total, LDL G HDL Cholesterol - H Triglycerides, Total Cholesterol - G Total, LDL H HDL Cholesterol

Health Benefits of Lipids

Recommended Intakes of Fat DRI: 20-35% of energy intake Cholesterol: 200-300 mg/day Linoleic acid AI 5% - 10% of energy intake Linolenic acid AI 0.6 - 1.2% of energy intake

Guidelines to Groceries Avoid ADDED and Invisible Fat Avoid Tropical oils Coconut oil Palm oil

Fat Distribution in Diet

Guidelines to Groceries Use whole, unprocessed vegetables, fruits, and grains without added fats

Guidelines to Groceries Use fat free milk and milk products

Guidelines to Groceries Use meat sparingly Use lean meats Use meat alternatives

Beware the Label “0 Trans Fat” – can still contain up to 0.5 grams Look for “partially hydrogenated vegetable oil” or “vegetable shortening” IOM recommends trans fat intake be “as low as possible”

Fat Substitutes “New” vegetable oils from “new” seed Fat substitues Soybean & other seeds with very low levels of linolenic acid More stable but less omega-3 fatty acid Fat substitues Z-Trim made from corn, soy, oat fiber Oatrim made from whole oats Fat replacers Artificial fats Olestra

Changing Guidelines for Fat Intake

Changing Guidelines Cook with olive oil or canola oil Nibble on nuts Monounsaturated fatty acids Nibble on nuts Omega-3 polyunsaturated fatty acids Feast on fish Marine omega-3 PUFA But beware of mercury Limit fatty meats, whole milk products, and tropical oils

Changing Guidelines Limit hydrogenated fat foods Fried foods (fried in solid fats) Fast foods (prepared in partially hydrogenated oils/fats Commercial baked goods Snack foods

Replacing Saturated Fat with Unsaturated Fat

Objectives After reading Chapter 4, class discussion and learning activities, you will be able to Identify types (classification) of lipids Describe the role of lipids in the body Discuss lipid digestion, absorption and transport Calculate calories from fat

Objectives Identify food sources of fats Discuss the health related effects of lipids Blood lipid profile Omega fatty acids Trans fatty acids Hydrogenation

The End!