Chapter Review

BRING IT HOME

CHAPTER 6 BRING IT HOME

Choosing added or cooking fats

Do you spread butter or margarine on your toast in the morning? At a restaurant, do you dip your bread in olive oil or spread butter on it? Do you add butter or margarine to your baked potato? When you prepare a meal, what type of fat do you use to sauté vegetables? Using the food labels provided here, answer the questions about these commonly used fats.

Consider

  1. To moderate saturated fat intake, which of the fats would you use sparingly?

  2. Which of these fats contain trans fatty acids? What word(s) might you find in the ingredient listing that would indicate the presence of trans fat?

  3. Of these fats, why is butter the only source of dietary cholesterol?

  4. At a restaurant, you have the option of spreading butter on your bread or dipping your bread in a seasoned olive oil. Which would you choose and why?

  5. You observe a friend prepare a pasta dish using a large amount of olive oil. Your friend says, “This stuff is great for you!” How might you respond? (Hint: Note the percent Daily Value for total fat on the label for olive oil.)

  6. Despite its high concentration of saturated fat, coconut oil has been advertised as a healthy fat and promoted on television for multiple benefits. Explore some of the science behind the claims for coconut oil by searching “coconut oil” in www.pubmed.gov. After reading 2 or 3 abstracts about the role of coconut oil in health, do you feel the evidence is sufficient to recommend the use of coconut oil as a cooking fat on a regular basis? What might you tell a friend who asks, “Is coconut oil healthy?”

139

KEY IDEAS

KEY IDEAS

  • Lipids comprise a group of structurally diverse compounds composed of carbon, hydrogen, and a small amount of oxygen that are insoluble in water.

  • Among their varied functions in the body, lipids serve as a component of cell membranes and in nutrient transport, as protection and insulation of internal organs, and as precursors for hormones.

  • Four classes of lipids include fatty acids, triglycerides, sterols, and phospholipids.

  • Fatty acids are the primary components of triglycerides and phospholipids. Dependent upon the number of hydrogen atoms filling their carbon bonds, fatty acids are either saturated or unsaturated with one or more double bonds determining their function in the body, as well as their role in health and disease.

  • Triglycerides, commonly referred to as “fat,” are the primary storage form of lipid in our bodies and the primary source of lipid in our diet, providing a concentrated energy source, essential fatty acids, and carriers of fat-soluble vitamins.

  • The essential fatty acids include linoleic acid (an omega-6 fatty acid) and alpha-linolenic acid (an omega-3 fatty acid), which are required for the synthesis of longer-chain fatty acids and, in turn, the production of eicosanoids.

  • Cholesterol is a sterol synthesized primarily by the liver in amounts sufficient to meet our needs, but is also consumed through foods of animal origin.

  • Most lipid digestion occurs in the small intestine facilitated by bile acids, the process of emulsification, and the action of lipases.

  • Protein-rich lipoproteins transport lipids in the bloodstream and include chylomicrons, low-density lipoproteins (LDLs), high-density lipoproteins (HDLs), and very low-density lipoproteins (VLDLs). Lipoproteins are classified according to their density and by their function; they differ in which lipids they carry to which body parts.

  • Depending on the type and amount in the diet, fat can have positive and negative health effects.

  • The current recommended fat intake is 20% to 35% of total calories.

  • Although some trans fatty acids are naturally occurring, most are produced through partial hydrogenation of polyunsaturated fats, and increase the risk of heart disease more than any type of fat.

140

NEED TO KNOW

NEED TO KNOW

Review Questions

Question 6.10

1. Characteristics of lipids include all of the following, EXCEPT that they are:

  1. structurally similar compounds with specific functions.

  2. composed of carbon, hydrogen, and oxygen.

  3. include triglycerides, phospholipids, and sterols.

  4. are generally insoluble in water.

1. a

Question 6.11

2. Dietary fat contributes to satiety by:

  1. increasing the glycemic response of a meal or snack.

  2. stimulating motility in the small intestine.

  3. prolonging the time food stays in the stomach.

  4. producing bulk to fill the stomach.

2. c

Question 6.12

3. Structurally, fatty acids:

  1. consist of carbon chains of similar lengths.

  2. differ in their degree of saturation.

  3. are composed of carbon rings with a hydrocarbon side chain.

  4. have a hydrogen and an oxygen attached to each carbon.

3. b

Question 6.13

4. A serving of cookies has seven grams of fat. How many calories from fat would these cookies provide?

  1. 7 calories

  2. 28 calories

  3. 49 calories

  4. 63 calories

  5. 70 calories

4. d

Question 6.14

5. Cholesterol is a sterol that:

  1. must be consumed in the diet to meet needs.

  2. provides nine calories per gram.

  3. is found in plant foods that are high in saturated fats.

  4. functions as a precursor for synthesis of steroid hormones.

5. d

Question 6.15

6. Emulsification of fats in the small intestine requires the presence of:

  1. bile acids.

  2. hydrochloric acid.

  3. lipases.

  4. cholesterol.

  5. insulin.

6. a

Question 6.16

7. Low-density lipoproteins (LDLs):

  1. transport cholesterol from the body’s tissues back to the liver.

  2. transport cholesterol to essentially all cells in the body.

  3. lower the risk of heart disease as their levels increase.

  4. aid in the digestion of lipids in the small intestine.

  5. are derived from chylomicrons as triglycerides are removed.

7. b

Question 6.17

8. Linoleic acid and linolenic acid:

  1. can be synthesized from phospholipids in the body.

  2. are both classified as omega-3 fatty acids.

  3. must be consumed through the diet to meet the body’s needs.

  4. are both saturated fatty acids.

  5. are both trans fatty acids.

8. c

Question 6.18

9. All of the following are true statements regarding trans fatty acids, EXCEPT:

  1. trans fatty acids are produced by complete hydrogenation of unsaturated fatty acids.

  2. trans fatty acids are present in small amounts in meats and full-fat dairy foods.

  3. trans fatty acids can increase LDL cholesterol levels.

  4. trans fatty acids can make packaged foods more resistant to spoilage, increasing shelf-life.

  5. trans fatty acids are listed on the Nutrition Facts Panel.

9. a

Question 6.19

10. What is the AMDR for total calories from dietary fat for adults?

  1. 5% to 20%

  2. 10% to 25%

  3. 15% to 30%

  4. 20% to 35%

  5. 25% to 40%

10. d

141

Take It Further

Trans fatty acids can be found in partially hydrogenated foods like stick margarine, commercially baked pastries and cakes, and many packaged cookies and crackers. Recently, the FDA proposed a possible ban on trans fat in the American food supply. Currently, foods that contain less than 0.5 grams of trans fat can list content on the Nutrition Facts Panel as 0. Discuss the rationale for the proposal to ban trans fat and include your perspective on whether a ban should be imposed by the FDA or whether concerned consumers should refer to the Nutrition Facts Panel.

Dietary Analysis Using SuperTracker

Dietary Analysis Using SuperTracker

Getting to know the lipids in your lunch

Lipids, or fats, are a key component of any healthy diet, but it’s important to know if we’re getting too little or too much. In this exercise, you will evaluate your lipid intake, break down the various types of fats you consume on an average day, and compare them with the current dietary recommendations.

Question 6.20

1. Log onto the United States Department of Agriculture (USDA) website at www.supertracker.usda.gov. If you have not done so already, you will need to create a profile to get a personalized diet plan. This profile will allow you to save your information and diet intake for future reference. Do not use the general plan.

Question 6.21

2. Click the Track Food and Activity option.

Question 6.22

3. Record your food and beverage intake for one day that most reflects your typical eating patterns. Enter each food and beverage you consumed into the food tracker. Note that there may not always be an exact match to the food or beverage that you consumed, so select the best match available.

Question 6.23

4. Once you have entered all of your food and beverage choices into the food tracker, on the right side of the page under the bar graph, you will see Related Links: View by Meal and Nutrient Intake Report. Print these reports and use them to answer the following questions:

  1. What percent of your total calories came from dietary fat? Is this within the recommended 20% to 35%? What foods contributed most to your overall intake of dietary fat?

  2. What percent of your total calories came from saturated fat? Is it more than 10%?

  3. What percent of total calories came from monounsaturated fat? Is this greater than your intake of saturated fat?

  4. What percent of total calories came from polyunsaturated fat? Is this greater than your intake of saturated fat?

  5. How many grams of linoleic acid did you consume? Is this within the dietary recommendations?

  6. How many grams of linolenic acid did you consume? Is this within the dietary recommendations?

  7. How many milligrams of cholesterol did you consume? Is this above the recommended 300 mg daily limit? What foods contributed the most cholesterol to your diet on this day?

  8. Considering what you’ve learned about trans fatty acids, what foods did you consume that might be sources of this type of fatty acid?

  9. What specific dietary changes could you make to improve upon the results of this day’s analysis? List at least three food substitutions that would not only help keep total fat intake within recommended range, but boost unsaturated fat intake over saturated. For example, choosing fish or poultry rather than ground beef.