This is the fourth Investigation in the LabLearner CELL Examining Nutrition. In this Investigation, students will focus on the importance of dietary lipids. 

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A. Begin the Investigation by reviewing the information students have learned thus far in this CELL.  Initiate a discussion by asking students the questions that follow.

1. Ask students: What are carbohydrates?  Are there different types of carbohydrates? Students should indicate that carbohydrates are one of six nutrients needed by the body to function properly.  One of the functions of carbohydrates is to provide energy to the body.  Carbohydrates include sugars, starches, and dietary fiber.

2. Ask students: What food groups and categories have foods that contain carbohydrates? Students should indicate that all the food groups and categories include foods that contain carbohydrates.

3. Ask students: What happens if your body gets more glucose than it can use? Student answers may vary.  The body uses glucose to meet any immediate energy needs. If there is more glucose than it needs, the excess glucose is stored in the body as another type of carbohydrate, glycogen, or as fat.

4. Ask students: Can eating excess sugar cause problems over time? Yes.  Excess sugar can lead to tooth decay, heart disease, diabetes, and obesity.

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Ask students to use the Mind Movies Cognitive Tool. Tell students that using this Cognitive Tool may help them to recall the answer to the question that follows: 

Ask students: What happens to the carbohydrates in foods after you put them in your mouth? Students should indicate that carbohydrates such as sugars and starch are mechanically and chemically digested into the sugar glucose, which is absorbed mainly through the walls of the small intestine and into the blood.  There, glucose is carried by the blood to the organs and cells of the body.  Most dietary fiber, however, is not digested to glucose.  Rather, it passes through the digestive tract, helping to push other undigested food along the tract. This function also helps the body maintain its health.   

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B. Explain to students that they will continue to learn about the nutrients listed on nutrition labels. In this Investigation, they will study another nutrient, lipids.  Ask students to locate their Scientist’s Glossary.

“Lipid: One of the six nutrients needed for the body to function properly. Lipids are found in plant and animal tissues. There are several types of lipids, including fats, oils, and waxes.”

1. Draw attention to the terms lipid and fat on the slide.  

Ask students:  What do you know about lipids?  About fat?  Have you heard of lipids or fats before? Student answers may vary.  Students should have noticed the term fats on the nutrition labels in the previous Investigation.  They most likely have heard the term mentioned in relationship to the nutrition practiced in their homes or in the news.  Many students may have heard that excess fat in their foods is not desirable.  It is likely that students have not heard the term lipid previously.

2. Ask students to look at the definition for the term fat in their Student Data Record.  

“Fat: A type of lipid that can be used by the body for energy. Most fat ingested is stored by the body for later energy use. The body generally uses carbohydrates as its first source of energy, relying on fats for energy once energy from carbohydrates is no longer as readily available. Two of the functions of fat in the body are to maintain body temperature and cushion the body’s organs.”

Explain that a lipid is one of the six nutrients the body needs in order to function properly.  Tell students that just as with the nutrient, carbohydrates, there are several different types of lipids.  Four different types of lipids are: fats, oils, cholesterol, and waxes. 

a. Explain to students that the term lipid is not listed on a nutrition label.  Explain that the term Fat is listed on the nutrition label because fat is one type of lipid that is essential for the body.

b. Ask students: What purpose does do you think fats have in your body? Student answers may vary.

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c. Explain to students that fats have several functions.

• They are stored and used later when the amount of carbohydrates in the body is not enough to meet energy needs.  Tell students that when foods that contain fats are consumed, the fats are mechanically and chemically digested, then stored in the body as fat.  Essentially, the body breaks down fat and then rebuilds it in order to store it.

• Fats also protect the body’s vital organs by forming a layer around them, much like a cushion. Look at the fat that helps protect a healthy heart on the left of the slide.

• Fats also insulate the body, helping it to maintain a constant temperature.

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C. Explain to students that they will continue to read the play about Jason and Dr. Greene.  This will assist in providing students with information about the nutrient, fat.  

Divide students into pairs and direct them to choose one of the characters in the play, Jason or Dr. Greene.

1. Ask students to locate Problem 1 of their Student Data Record.

2. Students will read:

Jason:  Where on the nutrition label can I find the amount of fat in the foods I eat or the beverages I drink?

Dr. Greene:  For the fat content, look in the part that lists Total Fat.  This part of the nutrition label is separated into several parts and shows the different types of fats in foods. Examples of the different types of fats are saturated fat, trans fat, polyunsaturated fat, and monounsaturated fat.

Jason:  You said that fats are a type of lipid?  Are fats solids or liquids?  Are there other types of lipids?

Dr. Greene:  Fats are solids.  Oils are lipids that are liquid.  Examples of oils include vegetable oil, coconut oil, and olive oil.  Waxes are a type of lipid that are not included on a nutrition label.  Examples of a wax are bees wax or ear wax.

Jason:  Why aren’t the other types of lipids listed on the nutrition label?

Dr. Greene:  The research done by scientists shows that fats are more important for the body’s health than waxes.  Therefore, only the different types of fats are listed on nutrition labels.

Jason:  What is the function of fat in the body?

Dr. Greene: Fats are stored in the body and used later to provide energy. Fats protect the body’s organs. Fats also insulate the body so it does not get too hot or too cold.

Jason: Can I eat too much fat?  Can I eat too little fat? 

Dr. Greene:  Yes, you can eat too much fat.  Too much fat may cause problems like heart disease and stroke.  Too little fat can also cause health problems such as skin problems, problems with cuts and bruises healing, and heart problems.  Remember Jason, it is unhealthy to eat too little of ANY of the six nutrients, and it is unhealthy to eat too much of ANY nutrients. 

Jason:  How do I know if I’m getting too much or too little fat from my foods? 

Dr. Greene:  You can check the nutrition labels of the foods you eat and look at the Percent Daily Value.  Remember, the goal is for all of your meals to provide no more than 100% of the Daily Value of fat a day. 

Jason:  Is there anything else that I should do? 

Dr. Greene:  Yes.  Remember to drink lots of water.  Water is a nutrient that many people often forget that they need. 

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3. Discuss what happened in the play with your class.  Encourage students to return to their seats and reflect on what they have learned thus far from the characters in the play.  The following directions may be useful in guiding the class discussion:

a. Organize the students into five cooperative groups.

b. Explain to the groups that they will be responsible for creating two questions that they will ask their classmates.  The goal of this activity is to assess students’ current comprehension of the concepts included in the play.

c. When the student groups have completed this task, they should read their questions aloud to the class.

d. Add several questions of your own to the students’ questions.

e. The questions that follow are sample questions that may be included in the discussion.

Ask students: What nutrient did Jason and Dr. Greene talk about? Students should indicate that they talked about lipids, specifically fats.

Ask students: Are there different types of lipids? Students should indicate that there are several different types of lipids such as fats, oils, and waxes.

Ask students: How are oils different from fats? Oils are another type of lipid.  Fats are solids and oils are liquids.

Ask students: Which fats might you see listed on a nutrition label? Students should indicate that they might see the total fat found in foods.  Other types of fats listed on the nutrition label may include saturated, trans, polyunsaturated, or monounsaturated fats.

Ask students: What functions do fats perform in the body? Students should indicate that fats are stored in the body and used later to provide energy; fats protect the body’s organs and insulate the body so it can maintain a constant temperature.