Chapter 5 Lipids

What Are Lipids? Hydrophobic/hydrophilic Lipophilic/lipophobic Classes of lipids Triglycerides Phospholipids Sterols © PhotoDisc

Fatty Acids Are Key Building Blocks Chain Length 4–24 carbons

Fatty Acids Are Key Building Blocks Saturation Saturated All single bonds between carbons Monounsaturated One carbon-carbon double bond Polyunsaturated More than one carbon-carbon double bond

Fatty Acids Are Key Building Blocks Geometric and Positional Isomers Cis fatty acid Trans fatty acids Hydrogenation Conjugated linoleic acid

Fatty Acids Are Key Building Blocks Types of fatty acids Omega-3 Omega-6 Omega-9

#6 Triglycerides Structure Functions Glycerol + 3 fatty acids Energy source Energy reserve Insulation and protection Carrier of fat-soluble compounds Sensory qualities in food

Function of Triglycerides Fat performs a number of essential functions in the body. Fat is also a major energy source. When at rest, muscles prefer to use fat for fuel.

Triglycerides in Food Sources of omega-3 fatty acids Soybean, canola, walnut, flaxseed oils Salmon, tuna, mackerel Sources of omega-6 fatty acids Vegetable oils Nuts and seeds © Photodisc

#2 Fat vs Oil Fat – solid at room temp Oil – liquid at room temp Butter, Lard, Crisco, Coconut oil Olive oil, canola oil

#3 Fatty acids Saturated fatty acid – full saturated with hydrogen, solid fats Monounsaturated – one double bond, liquid oil Polyunsaturated – two or more double bonds, liquid oil Trans fatty acid – lab made fat, solid fat like crisco

# 4 Essential Fatty Acids Characteristics of Omega 3 and 6 Essential (EFA)- Have to consume in diet Unsaturated fats Deficiency is rare – leads to scaly skin rash, dermatitis, poor growth, lower immune system Characteristics of Omega 9 Nonessential – body can synthesize

#5 Functions of Fatty Acids Omega 6 Fats Too much (eicosanoids) may promote inflammation, constrict blood vessels and cause clotting. 18:6 Fat sources Nuts, seeds and corn oil

#5 Functions of Fatty Acids Omega 3 Fats Improves inflammatory conditions: arthritis, psoriasis, asthma and skin conditions Improves ulcerativie colitis and Chron’s disease Lowers Triglycerides and Raises HDL, reduces clotting, lowers blood pressure Reduces insulin resistance, lowers Diabetes risk Preserves renal function and reduces vascular access thromobosis in dialysis patients. Reduces severity of Alzheimers, deperssion, and bipolar Improves growth and development of brain

Omega 3 sources Omega 3 sources Fatty fish Canola, soybean, walnut and flaxseed oil

#8 Fats in our foods Saturated Fat pg 190 Butter Coconut oil Lard Beef Tallow

#8 Fats in our Foods Monounsaturated Fats Olive oil Peanut oil Safflower

#8 Fats in Our Foods Polyunsaturated fats pg 190 Sunflower oil Corn oil Soybean oil Cotton seed oil

Top Foods with Trans Fats 1. Spreads. Margarine Stick margarine has 2.8 grams of trans fat per tablespoon, and 2.1 grams of saturated fat. Tub margarine has 0.6 grams of trans fat per tablespoon, and 1.2 grams of saturated fat. Shortening has 4.2 grams of trans fat per tablespoon, and 3.4 grams of saturated fat. 2. Processed foods: shelf stable cookies, donuts, cornbread mixes, pancake mixes, crackers and chips 3. Non dairy creamers, whipped topping, gravy mixes, salad dressings

Video Facts about Fats http://science.howstuffworks.com/life/1998-how-trans-fats-work-video.htm

#12, 13 Phospholipids Structure Functions Food sources Glycerol + 2 fatty acids + phosphate group Functions Component of cell membranes Lipid transport as part of lipoproteins Emulsifiers Food sources Egg yolks, liver, soybeans, peanuts

#14, 21 Transport Lipids in the Body Lipoproteins carry lipids around the body Chylomicrons Delivers dietary lipids from intestines to cells and liver

#14, 21 Transport Lipids in the Body Very low density lipoproteins (VLDLs) Deliver triglycerides to cells Intermediate-density lipoproteins Remove some phospholipids Low-density lipoproteins (LDLs) Deliver cholesterol to cells High-density lipoproteins (HDLs) Pick up cholesterol for removal or recycling

#15-17 Sterols: Cholesterol Structure - multi ring Functions Component of cell membranes Precursor to other substances Sterol hormones Vitamin D Bile acids Synthesis Made in the liver-1000mg/day Food sources Found only in animal foods Cholesterol and Vitamin D occur in foods

Cholesterol in the diet 186-212 mg per large egg yolk 324 mg in 3 oz beef liver 24 mg in whole milk, 5mg in skim milk 31 mg in 1 TBSP butter 73 mg per 3 oz lean pork 76 mg per 3 oz ground beef Breastmilk is high in cholesterol for brain development Daily recommendation is <300mg/day

#18-20 Lipid Digestion and Absorption Mouth and stomach Minimal digestion of triglycerides Small intestine Emulsified by phospholipids Digested by pancreatic lipase Absorbed into intestinal cells Formed into chylomicrons and moved into lymphatic system

#19 Lipid Digestion/Absorption CCK – hormone cholecystokinin Is released from small intestine Bile – CCK signals gallbladder to contract to release BILE into duodenum and emulsifies fats Lipase – Pancreatic lipase digests TG Know how many grams of fat you need a day to make the gallbladder contract? 10 grams a day

#21 Lipid Digestion and Absorption Digestibility Steatorrhea – fatty, frothy stools indicate fat malabsorption, pancreatic issues <7grams of fat should be in stools in a 24 hour time frame Most fat absorption takes place in Duodenum or jejunum in Small intestine Cholesterol carried out with soluble fiber

#22 Negative Health Effects of Lipids Obesity High-fat diets promote weight gain Heart disease High saturated and trans fat intake raises LDL cholesterol Cancer

#22 Positive Health Effects of Lipids Omega 3 Fats: Reduce inflammation Reduce heart disease risk To increase Omega 3 : 1.5-2 tsp canola or soybean oil each day 4 meals containing fatty fish each week. Mackerel, tuna, salmon, trout, herring or cod liver oil

#23 Fat Recommendations in the Diet Recommended intake Consume at least two weekly servings of oily fish Balance of calories from fat and carbohydrate Reduce sat and trans fat intake Total fat: 20–35 percent of calories Need ~2 percent of calories as essential fatty acids Improve balance of omega-3: omega-6 fatty acids

AHA Position on Omega-3 Fatty Acids The American Heart Association recommends eating fish (particularly fatty fish) at least two times a week. Fish is a good source of protein and doesn’t have high saturated fat that fatty meat products do. Fatty fish such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon are high in two kinds of omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Lipids in the Diet Fat substitutes The Olestra Controversy: Are Fat Replacers Safe? composition Sucrose + fatty acids Indigestible – provides zero kcals and causes diarrhea Reduces absorption of fat-soluble vitamins

A Healthy Balance An appropriate balance of calories from fat and carbohydrates can have multiple health benefits aside from controlling weight. These include cholesterol levels, vitamin intake, etc.

Recommended Fat Intake The Dietary Guidelines for Americans recommends a fat intake of 20 to 35 percent of total calories. Saturated fat should supply no more than 10 percent of our total calories, or about one-third of our fat calories.

NCEP Tips for Healthful Eating Out Choose restaurants that have low-fat, low-cholesterol menu items. Don’t be afraid to ask for foods that follow your eating pattern. Select poultry, fish, or meat that is broiled, grilled, baked, steamed, or poached rather than fried.

Adult Cholesterol Level Recommendations Total Cholesterol : <200 mg/dL >240 mg/dL is High blood cholesterol. A person with this level has more than twice the risk of coronary heart disease as someone whose cholesterol is below 200 mg/dL. Soluble fiber, exercise, and heart healthy diet improve total cholesterol

Adult Cholesterol Level: HDL – High Density Lipoprotein The GOOD cholesterol >60 mg/dL Improve levels by exercise, heart healthy diet, fatty fish, and Lethicin supplement (1200mg 3 x day) Lethicin converts LDL to HDL

Adult Cholesterol Level: LDL : BAD <100mg/dL Improve levels by exercise, low saturated/trans fat diet, lethicin supplement

Adult Cholesterol Levels Triglycerides <150 mg/dL Avoiding high sugar foods, pastries, sodas, alcohol, Control weight