Chapter Three: Lipids Identify the major roles of body fat Identify the 3 classes of body lipids Identify the chemical structure of triglycerides and three ways fatty acids differ from one another Identify food sources of fats, how they differ in saturation, and the dietary recommendations of each type of fat

Lipids contd. Identify the roles of phospholipids and sterols Identify the current daily dietary recommendations for fat intake Identify artificial sources of fat Explain what a trans-fatty acid is and where it is found

What do you already know? Lipids (fats) in review Energy provided: 9 kcals. per gram No more than 30% of kcals. per day Sources in the Food Guide Pyramid Milk, yogurt and cheese group Meat and meat alternates group Fats, oils and sweets group

Nutritional Role of Lipids Main function is for fuel or energy Supplies about 60% of energy needs Unlimited storage Other roles of fats Nourishment for hair and skin Insulates and cushions organs & breasts Major material of cell membranes Most concentrated form of energy

Forms of Lipids Triglycerides: Fat storage in the body Make up of three fatty acids attached to a backbone of glycerol Makes up 95% of fat in the body and in the diet Phospholipids: portion of other 5% of lipids found in the body Found in the cell membrane Not essential—supplement not necessary

Forms of Lipids contd. Sterols: portion of other 5% of lipids found in the body Forms are cholesterol, Vitamin D, and sex hormones Cholesterol is found in cells and used in metabolism—rec. level is below 200 mg/dl in the blood

Triglycerides

Fatty Acids and Their Saturation Levels Saturated fats: No more than 10% Contain all the hydrogen they can hold Examples are animals fats, palm and coconut oil Hard at room temperature Known to increase cholesterol levels

Dietary Fats

Fatty Acids cntd. Monounsaturated Fats: 10% One point of saturation is missing Examples are plant foods such as nuts, avocados, and olive oil Softer at room temperature Have a neutral effect on cholesterol levels

Fatty Acids cntd. Polyunsaturated fats: No more than 10% (PUFAs) Missing multiple points of saturation Examples are vegetables oils Liquid at room temperature Known to lower cholesterol levels Sources spoil more easily at room temperature

Fat Substitutes Carbohydrate based: Oatrim & Z-Trim Stable when heated Provides fiber and reduces kcals by ½ Protein based: Simplesse Found in dairy products and dressings Not stable when heated Reduced kcals. By 80%

Fat Substitutes contd. Fat-based: Olestra Indigestible Stable when heated and tastes like fat Can cause digestive problems and nutrient losses

Cutting Fat Intake & Choosing Unsaturated Fat Sources Choose low fat sources Choose low fat cooking methods Avoid hydrogenated fats Avoid fast foods—chips, baked goods and commercially-prepared foods Trans-fatty acids: formed from the hydrogenation of PUFAs

Test Questions 1. Which of the following fats is the stored fat in the body and available for energy. A. Cholesterol B. Phospholipids C. Triglycerides D. Lecithin

Test Questions 2. The term “unsaturated fat” means that: A. The fat lacks glycerol B. Hydrogen ions are missing in the fatty acid chains C. The carbon chains in the fat are less than ten D. The fat is hard or solid at room termperature