Chapter 3 Fats Fats are an essential nutrient to the body. Excessive intake of fats can contribute to chronic diseases. Ask the class to provide examples. What foods are examples of fats?

Chapter 3 Lesson 3.1 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Key Concepts Dietary fat supplies essential body tissue needs, both as an energy fuel and a structural material. Foods from animal and plant sources supply distinct forms of fat that affect health in different ways. Excess dietary fat, especially from animal food sources, is a negative risk factor in overall health. Remind the students that fat is essential. Diets containing very little to no fat are not healthy. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

The Nature of Fats Dietary importance Classes of fats Concentrated fuel for energy Classes of fats Lipids Glycerides Triglycerides Fatty acids Lipoproteins Why is fat considered a back-up fuel source for the body? Carbohydrates are the primary fuel, followed by fat when needed. Explain that each class of fat serves a different purpose in the body and all are considered lipids. What is meant by “concentrated” fuel source? Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Fatty Acids Saturated fatty acids Unsaturated fatty acids Filled or “saturated” with hydrogen Unsaturated fatty acids Not completely filled with hydrogen Less heavy, less dense Monounsaturated: one unfilled spot Polyunsaturated: two or more unfilled spots Saturated fats are heavier, denser, and more solid than unsaturated fats. Unsaturated fats are usually in oil form. What foods supply monounsaturated fats? Olive and olive oil, peanuts and peanut oil, canola oil, almonds, pecans, and avocados Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Essential Fatty Acids Polyunsaturated fatty acids Linoleic (omega-6) Alpha-linolenic (omega-3) Explain that essential means these fats MUST come from the foods we eat. We cannot produce these as we can the other types of fatty acids. How much of a daily dietary intake needs to be from fat to supply adequate amounts of essential fatty acids? 10% Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Types of Fatty Acids Point out the different bonds and the essential fatty acids. What foods are high in essential fatty acids? Figure information: Modified from Grodner M and others: Foundations and Clinical Applications of Nutrition, ed 4, St Louis, 2007, Mosby. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Phospholipids Triglyceride derivative: third fatty acid replaced by phosphate group Partially hydrophobic, partially hydrophilic Major constituents in cell membranes Allow transport of fats through bloodstream Explain why phospholipids are needed for transport in the bloodstream by using the concept of water and oil separation. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Phospholipid Bilayer Explain the concept of “like attracts like” as related to the hydrophobic and hydrophilic parts of a phospholipid. Figure information: From NASA Astrobiology Institute, Washington, DC, http://nai.nasa.gov, accessed July 6, 2007.) Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Cholesterol Not a fat A fat-related compound From animal foods Egg yolks Liver, kidney Meats Synthesized in the liver Diet should be low in cholesterol Linked with heart disease There is no cholesterol in plant foods; it is synthesized only in animal tissues. There is no biologic requirement for cholesterol in the diet. What does this mean? What are some health risks associated with increased cholesterol levels? There is a link between cholesterol intake and increased risk for coronary heart disease. Explain that saturated fat is often found in foods high in cholesterol, which may also add to an increase in blood cholesterol levels. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Functions of Fat in Foods Fat in foods provide: Energy Essential nutrients Flavor and satisfaction Fat substitutes are not absorbed and therefore do not provide energy or essential nutrients but may provide flavor and satisfaction Fat provides 9 kcal/g versus 4 kcal/g for carbohydrates. Explain that this is an effective way to store energy. Food fats supply the body with essential fatty acids and carry fat-soluble vitamins. Do fat substitutes carry fat-soluble vitamins? What are examples of fat substitutes? Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Functions of Fat in the Body Adipose tissue Protects organs Helps regulate temperature Cell membrane structure Forms part of cell membrane Helps transport nutrients across cell membranes Fat is stored in adipose tissue. What are some common sites of adipose tissue deposits? Explain that a special fat covering protects nerve fibers and helps relay nerve impulses. What type of fat that has been previously discussed forms cell membranes? Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Food Sources of Fat Animal fats Plant fats Hydrogenated fats Commercial fat products raise health concerns Cis form Trans form Food industry now offers trans-free products The majority of saturated fats comes from animal sources. What plant sources contain saturated fats? Coconut and palm oils are saturated fats used mainly in commercially processed food items. Plant foods supply mostly monounsaturated and polyunsaturated fats. What is a good source of polyunsaturated fats? Fish Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Trans Fatty Acid Why were trans fats first produced? More economical and shelf stable What types of foods are high in trans fats? Restaurant foods, fast foods, packaged foods When was the amount of trans fat a required item on the Nutrition Facts food label? 2006 Why are trans fats “worse” than saturated fats? Studies show they lower HDL cholesterol and raise LDL cholesterol, whereas saturated fats only raise LDL cholesterol, leaving HDL the same or better. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Food Label Information Calories from fat Calories from saturated fat* Total fat Saturated fat Polyunsaturated fat* Monounsaturated fat* Cholesterol *Voluntary information The FDA regulates food labeling. Explain how and why it does so. Why are some nutrients only voluntarily reported? Do the students think that food manufacturers would add the voluntary information if it showed an amount of a nutrient the consumer would see as “bad”? Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Characteristics of Food Fat Sources Visible fat Invisible Fat What are sources of visible fat? What are sources of invisible fat? Figures information: Copyright JupiterImages Corporation. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

FDA Health Claims Link one or more dietary components to the reduced risk of a specific disease Fat and cancer Saturated fat and cholesterol and heart disease Explain that research supports these claims. Explain that claims between a food and disease are regulated by the FDA, but many claims are not. For example, the FDA does not regulate claims that sound similar to food-disease claims such as “heart friendly.” Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Chapter 3 Lesson 3.2 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Key Concepts Dietary fat supplies essential body tissue needs, both as an energy fuel and a structural material. Excess dietary fat, especially from animal food sources, is a negative risk factor in overall health. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Dietary Fat and Health The American diet is high in fat. Excess calories are stored as fat. Animal food sources contribute to excess cholesterol and saturated fat in the diet. A decrease in saturated fat reduces serum total cholesterol. Monounsaturated fats reduce LDL cholesterol when substituted for saturated fat. Why are excess calories stored as fat and not carbohydrate or protein? Explain that storing excess energy as fat is the way the body is supposed to work. It is a machine meant to store the most energy in the least amount of space. Heart disease continues to be one of the leading causes of death in developed countries. Much attention is focused on reducing risk factors leading to this disease. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Digestion of Fats Mouth Stomach Small intestine Bile from the gallbladder Enzymes from the pancreas Enzymes from the small intestine Absorption The primary digestion action occurring in the mouth is mechanical. Foods are broken up into smaller particles through chewing and moistened for passage into the stomach. Little, if any, chemical fat digestion takes place in the stomach. Why do you think this is? Prompt the students to remember the principle of “like attracts like”; stomach acid is more attracted to hydrophilic compounds than hydrophobic compounds. What is the function of the gallbladder in fat digestion? Explain what an emulsifier is. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Dietary Fat Requirements Healthy diet guidelines: Stress the health benefits of a diet low in fat, saturated fat, and cholesterol Recommend that the fat content should not exceed 20% to 35% of total kilocalories Less than 10% of kilocalories should be from saturated fat Dietary cholesterol should be limited to 300 mg/day Calculate the amount of fat grams in a 2000-calorie diet at 20% and 35%. Tell the class how much cholesterol is in one egg. According to these guidelines, can one egg be eaten every day? Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Dietary Reference Intakes Linoleic acid: 17 g/day for men 12 g/day for women Linolenic acid: 1.6 g/day for men 1.1 g/day for women Current U.S. diet at ratio of 8:1 to 12:1 Recommended ratio of 2:1 to 3:1 Ask the students which essential acid is omega-6 and which is omega-3. What can the students eat more of to make their ratio closer to the recommended? Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Dietary Guidelines for Americans Control saturated fat and cholesterol Use only lean cuts of all meats; use more poultry and seafood Limit eggs to two or three per week Use low-fat or fat-free milk and milk products Avoid adding too much fat in food preparation By using these tips, people can significantly reduce their fat intake. What are some other tips that can help reduce fat in your diet? Mosby items and derived items © 2006 by Mosby, Inc. Slide 24 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Summary Fat is an essential body nutrient Fat serves as a back-up storage fuel for carbohydrate Fat supplies structural material for cell walls, protective padding for vital organs, insulation to maintain body temperature, and covering for nerve cells Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Summary, cont’d Classes of fat include lipids, triglycerides, fatty acids, and lipoproteins Fatty acids can be saturated or unsaturated Essential fatty acids are necessary to aid in tissue strength, cholesterol metabolism, muscle tone, blood clotting, and heart action Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.

Summary, cont’d Cholesterol is a sterol that is vital in human metabolism Cholesterol is only found in animal foods Digestion of fat includes digestive agents such as bile and pancreatic lipase Fatty acids and glycerides are incorporated into chylomicrons and absorbed via the lymphatic system into the bloodstream Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.