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

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A. Begin the Investigation by reviewing the information students learned in the previous Investigation of this CELL.  Initiate a discussion by asking the following questions:

1. Ask students: What are the six nutrients needed for the human body to function? Students should indicate that the six nutrients are water, carbohydrates, lipids (fats), proteins, vitamins, and minerals.

2.  Ask students: What are fats?  Are there different types of fats? Students should indicate that fats are a type of lipid.  Lipids, one of the six nutrients needed by the body, include fats, oils, and waxes.  Oils are fats that are in a liquid state of matter at room temperature, while fats at room temperature are in a solid state of matter.  One of the functions of fats is to provide energy to the body.  Once the body has used its available supply of glucose from carbohydrates, the fats stored in the body can be used for energy. Fat in the body also helps protect and cushion the organs of the body.

3. Ask students: Which food groups or categories have foods that contain fats? Students should indicate that all the food groups and categories include foods that contain some fats, but the fruits and vegetables groups generally do not contain as many fats as the other food groups.

4. Ask students: Can excess fats in the body cause problems? Can eating too little fat cause problems? Yes.  As with all other nutrients, eating too much or too little of fats can cause health problems.

5. Ask students: Do you have to give up your favorite foods to maintain a healthy balance of nutrients? Students should realize that if a favorite food is high in a nutrient such as fat, they don’t have to give it up.  They just need to balance that food with other foods that are low in fat for the rest of the day so that they do not greatly exceed their total Daily Value of fat.

6. Ask students: What information does the Daily Value for a nutrient provide?  What information does %DV for a nutrient provide? Students should indicate that the Daily Value for a nutrient is the total amount of the nutrient that is needed each day for the body to function properly.  The Daily Value for a nutrient is generally expressed in quantities of grams or milligrams.  Percent Daily Value is information found on nutrition labels that indicate the portion of a nutrient’s Daily Value that is found in one serving of a food or beverage.

7. Ask students:  Can you tell what nutrients such as carbohydrates, proteins, and sugars look like by looking at them?  No.  Nutrients are too small to see with the eye. The only way to know the nutrients found in a food is to look at its nutrition label.

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

1. Refer to the term protein at the top of this slide.  Ask students:  What do you know about proteins? Have you heard the term before? Student answers may vary.  Students should have noticed the term on the nutrition label during the previous investigations.  They most likely have heard the term mentioned in relationship to the nutrition practiced in their homes or in the news.  Most students know meat is a good source of protein.  Many students may have heard that protein is important for their health.

“Proteins:  One of the six nutrients the body needs to function properly. Proteins serve many functions in the body including the building and repairing the body’s tissues.”

2. Direct students to look at the definition for the term protein.  Explain that proteins are one of the six nutrients the body needs to function properly.

a. Tell students that when foods containing proteins are consumed, they are mechanically and chemically digested into smaller structures called amino acids.

b. Ask students: Does this process of breaking down protein into smaller units sound familiar?  Does this happen with any other nutrient that we have studied during the Core Experience? Students should indicate that this process sounds similar to the breakdown of carbohydrates into the sugar glucose.

• Explain that when proteins are broken down into amino acids, the amino acids are used by the body to help build structures in muscles and in other organs. Sometimes the body uses amino acids to make different proteins.  In this way, the breakdown of proteins is also similar to the breakdown of fats that students studied in Investigation Four.  The proteins are broken down into amino acids, absorbed into the blood, and then rebuilt into different proteins in the different organs of the body.

• Help students to understand that one of the reasons that the body goes through the process of breaking down a nutrient only to rebuild it is because many nutrients cannot be absorbed into the blood until they are broken down into smaller substances.  The smaller substances can be absorbed into the blood.  Once in the blood, the smaller substances can then be used to rebuild the nutrient.

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c. Explain to students that proteins perform many important functions in the body.

• Ask students:  Do you recall the name of the chemicals that help to digest food in the stomach and small intestines? Student answers may vary.  Students may recall that enzymes help to digest their food.

• Tell students that enzymes are a type of protein that helps chemical reactions in the body to occur, such as the digestion of food in the digestive system.

• In addition to helping in the digestion of food, proteins serve many other functions in the body.

• Discuss the functions of proteins in our bodies. This slide contains just a few of protein’s many functions.

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C. Instruct students to think about the story of Jason and Dr. Greene.  Ask students:  What questions do you think Jason could ask Dr. Greene about proteins?

1. Explain to students that they will have a brainstorming session during which they will think of questions Jason should ask Dr. Greene.  Students should be able to suggest questions based on what Jason asked during previous visits and on what they have learned so far about the other nutrients, carbohydrates, and fats.

2. Record some of the questions suggested by students on the board.  Sample questions students could suggest are as follows:

a. Is there more than one type of protein?

b. What is the function of proteins in the body?

c. How is protein listed on a nutrition label?

d. How many servings of protein do you need each day?

e. Can you eat too much or too little protein?

3. Continue to read the story of Jason and Dr. Greene.  Students should take turns as the characters of Jason and Dr. Greene.

a. Ask students to locate problem 1 of their Scientist Data Record.

b. Students will read:

Jason:  Where would I find information about protein on a nutrition label?

Dr. Greene:  Protein is listed as protein on the nutrition label.

Jason:  How do I know how much protein I’m getting from my foods?

Dr. Greene:  You can check the nutrition labels of the foods you eat.  The label lists how many grams the food item contains, but the Recommended Daily Value, or RDV, for protein is not usually listed on the label.  The Percent Daily Value (%DV) is also not usually listed on the nutrition label.

Jason:  Why doesn’t the nutrition label have the RDV or the Percent DV listed for protein?

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Dr. Greene:  One reason that information about Recommended Daily Values for nutrients appears on food labels is that scientists found that there are some nutrients that people either have too little of or too much of.  Scientists and the Food and Drug Administration wanted to help people obtain the amounts of these nutrients that they needed.  These nutrients have the Percent Daily Value on the nutrition label. When scientists did their research, protein was not one of the nutrients that people either consumed too little of or too much of.  That’s why the Percent Daily Value for protein is not required on nutrition labels.  Protein is only required to be listed if the manufacturer states that the food item is high in protein. 

Jason:  Does that mean that there is not a Recommended Daily Value for protein? 

Dr. Greene:  No.  As with the other nutrients, scientists have made recommendations for a Daily Value for protein.  It is between 50 and 75 grams of protein a day.  This is what an adult would need for a healthy body.  Children often need a little more protein and older adults need a little less.   

Jason:  Could I find out how much protein a 2-year-old child would need? 

Dr. Greene:  Yes.  The Food and Drug Administration is the organization that sets the Daily Values.  This organization would have information about the different amounts of protein needed by young children and older adults 

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

Dr. Greene:  Yes.  Like any of the other nutrients, eating too much or too little protein can cause health problems.  However, following MyPlate is a good way to make sure that you are getting just the amount of protein your body needs to function properly.   

Jason:  Is there anything else that I should do to stay healthy? 

Dr. Greene:  Yes.  Remember to drink lots of water and eat the daily recommended amounts from the food groups shown in the MyPlate graphic.  Although you haven’t asked about them, you also need vitamins and minerals to stay healthy.  Vitamins and minerals are found in all of the food groups and categories shown in MyPlate. 

Jason:  So if I follow the MyPlate graphic, I will get the Daily Value of the vitamins and minerals that I need? 

Dr. Greene:  Yes. 

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4. Encourage students to reflect on what they have learned thus far from the characters in the play.  The following questions may be useful in assessing whether students understood the information presented during the play:

a. Ask students: What nutrient did Jason and Dr. Greene talk about? Students should indicate that they talked about protein.

b. Ask students: How is protein listed on a nutrition label? Students should indicate that protein is listed as Protein on a nutrition label.

c. Ask students: Why are the Recommended Daily Values and %DV listed on a nutrition label? Scientists and the FDA wanted to help people consume the nutrients they need each day.  Scientists discovered that people often consume too much or too little of certain nutrients, so information about nutrients that tend to be consumed too little of or in excess amounts are on nutrition labels.

d. Ask students: Is there a %DV listed for protein?  Why? Not usually.  Scientists found that people generally do not consume too little or too much protein.  Manufacturers are not required to list a %DV for protein unless it claims that the food item is high in protein.

e. Ask students: Does this mean that there isn’t a Daily Value for protein? Students should indicate that an RDV for protein exists.  It is about 50 – 75 grams of protein a day.  However, children may require a little more and older adults a little less.

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D. Tell students they will conduct an experiment in this Investigation that will help them use nutrition labels to determine the amount of protein they consume in different foods.  As they conduct their experiment, they should think about the following questions:

• How much protein is in different foods?

• Are proteins found in all the food groups and categories?