Case Teaching Notes for
“Another Can of Bull? Do Energy Drinks Really Provide a Source of Energy?”

Introduction / Background

This case study is a “clicker case.” It combines the use of student personal response systems (clickers) with case teaching methods and formats. The case is presented in class using a series of PowerPoint slides in parts, or stages. After each stage, students are asked to respond to questions (called “clicker questions”) posed by the instructor. In this way, students work their way through the material to understand the problem presented in the case. Specifically designed for use in large introductory science classes, the method integrates lecture material, case scenario material, student discussion, (clicker) questions, clarification of the answers to those questions, more lecture, and data.

This case introduces students to basic principles of metabolism and energy through a biochemical analysis of the components of the commonly available “energy drinks” that many students purchase at fairly high prices. It is adapted from a case published in the National Center for Case Study Teaching in Science’s case collection, “A Can of Bull: Do Energy Drinks Really Provide a Source of Energy?” by Merle Heidemann, Division of Science and Mathematics Education, Michigan State University, and Gerald Urquhart, Lyman Briggs School of Science, Michigan State University.

Objectives

Following this case, students will be able to:

• Define energy in a biological / nutritional context.
• Identify valid biochemical sources of energy.
• Discuss how foods are metabolized to generate ATP.
• Critically evaluate marketing claims for various energy drinks.

Misconceptions

• Caffeine is a source of energy.
• Energy drinks are healthy.

Prerequisite Concepts

Students should already be familiar with cellular respiration.

Supporting Material

There are two web-based video clips included in the case:

• http://abcnews.go.com/Video/playerIndex?id=2622366
• http://www.cbsnews.com/video/watch/?id=3465186n%3fsource=search_video

The first is a news report on the growing trend of energy drinks and begins the case. The second is a news report on the dangers of mixing energy drinks with alcohol and ends the case. The reports are available from abcnews.go.com and cbsnews.com and are hyperlinked within the case. It is also possible to copy and paste the hyperlinks into any browser.

Additionally, students will require three handouts in order to evaluate the biochemical components of each energy drink:

• Ingredients and Nutrition Facts—lists the ingredients and nutritional content of each energy drink analyzed in this case as provided by the manufacturer.

• Biochemical Information—describes the function of many common ingredients found in energy drinks; this handout will help guide students in assigning the ingredients of their given energy drink to the proper “energy category.”

• Assignment—to be used by each student group when recording the “energy category” of each ingredient of their assigned energy drink.

These handouts can either be passed out to the students on the day of class or, alternatively, can be uploaded to a course management website and students can be required to download the handouts themselves (our preference).

Classroom Management

This case was written as an interrupted case using the personal story of a fictional character, named Rhonda, who is a writer for Running Magazine. Rhonda has been assigned to write a report on the new trend of drinking “energy drinks”—so-called functional foods. Prior to writing her report, she must do some research evaluating the various energy drinks’ marketing claims and whether they have any scientific validity.

The case proceeds through four main steps:

1. An introduction to energy drinks and the marketing claims associated with four common ones: Red Bull^®, Lo Carb Monster Energy^®, Sobe Adrenaline Rush^®, and Impulse™;
2. A brief review of cellular respiration and biological energy;
3. An analysis of the biochemical components of each of the four energy drinks and a determination of whether or not they are viable sources of energy; and
4. A final look at the effects of mixing energy drinks and alcohol.

We teach this case in an introductory biology course for either science majors or non-majors. Typical class size is 115. The three-credit class consists of three 55-minute weekly meetings in a lecture classroom with no recitation section, although students are required to meet once a week for a laboratory component (22 students/lab section).

Teaching the Case

Slide 1: Title slide.

Slide 2: Students begin the case by viewing an ABC news report on the popularity of energy drinks. In this report, the accuracy of the marketing claims is called into question.

Slide 3, Slide 4, and Slide 5: These slides are a series of three clicker questions that assess the students’ knowledge of and behavior regarding energy drinks.

Slide 6, Slide 7, Slide 8, Slide 9, and Slide 10: In these slides, students are introduced to the protagonist of the case, Rhonda, and the task assigned to her by her boss, Charley. Rhonda has been asked to evaluate the marketing claims of energy drinks in terms of their scientific accuracy for an upcoming article in Running Magazine.

Slide 11, Slide 12, Slide 13, and Slide 14: The marketing claims of four common energy drinks, Red Bull^®, Lo-Carb Monster Energy^®, Sobe Adrenaline Rush^®, and Impulse™, are listed on each of these slides. The instructor will immediately notice that the marketing claims of these drinks are well tailored to college-aged students.

Slide 15: The caloric content of each drink is given on this slide and compared with a can of Coca Cola^®. The idea behind this information is to begin to get students thinking about nutritional energy versus stimulants. Typically, energy drinks do not contain any more calories than regular soft drinks and quite often contain less, e.g., Lo-Carb Monster Energy^®. What they do contain is a large amount of stimulants in the form of caffeine (addressed later in the case).

Slide 16: This slide provides the overriding questions for the entire case: What is meant when we say something gives us energy, and what is the biological definition of energy? At this point, typically the instructor will spend 5–10 minutes discussing the concept of energy and also determine what misconceptions students have regarding energy.

Slide 17: A clicker question that assesses what students already know with regard to quantification of nutritional energy. Following this question, the instructor may choose to discuss the difference between kilocalorie and calorie, and the fact that what we actually read on nutritional labels is by definition kilocalories. In an advanced class, the relationship between joules and calories can also be taught at this point.

Since students should already be familiar with the concept of cellular respiration and carbohydrate metabolism, the next few slides only provide a brief review of important concepts in metabolism: basics of glycolysis, Krebs Cycle, electron transport, and ATP synthesis.

Slide 18: Stresses the fact that ATP is by definition the primary molecule of cellular energy. Instructors should point out that the potential energy held in the phosphate bonds on ATP (released upon hydrolysis) provides the chemical energy to drive most cellular processes. In more advanced courses, the instructor might choose to also discuss the role of GTP hydrolysis in driving many cellular processes.

Slide 19: Explains how foods (specifically focusing on carbohydrates) are linked to ATP production through the process of metabolism.

Slide 20: Provides the big picture of how photosynthesis and cellular respiration are connected to drive the formation of ATP. It also highlights (as does the previous slide) the fact that ATP can be produced under both aerobic and anaerobic conditions. The picture of runners on this slide can be used as an example of how under conditions of oxygen depletion (strenuous exercise) muscles will switch to lactic acid fermentation in order to continue to provide ATP for muscle contraction.

Slide 21: A clicker question that assesses the students’ knowledge of preferential catabolism of carbohydrates over other biological macromolecules.

Slide 22: Illustrates the overall process of cellular respiration. This slide provides an introduction to the review of glycolysis, Krebs Cycle, and electron transport chain that follow on the next few slides. This slide is a good spot to also reinforce the specific cellular location for each of the processes.

Slide 23 and Slide 24: Review the concept of glycolysis. Slide 24 is provided as a resource and may be deleted in an introductory course at the instructor’s discretion.

Slide 25: A clicker question to review the basic products produced by glycolysis alone.

Slide 26 and Slide 27: These slides review the concept of the Krebs Cycle as a series of oxidation/reduction reactions that are used to generate high energy electron carriers. Slide 27 is provided as a resource and may be deleted in an introductory course at the instructor’s discretion.

Slide 28 and Slide 29: These slides review the electron transport chain and the ATP synthase. Instructors will want to reinforce that it is the energy of electron movement that drives the pumping of protons across the inner mitochondrial membrane that establishes a concentration/pH/electrochemical gradient that then drives the formation of ATP. A frequent misconception among students is that it is the movement of electrons that drives the synthesis of ATP.

Slide 30: Presents a higher order clicker question that assesses the students’ ability to transfer their understanding of metabolism to weight loss.

Slide 31: Students are brought back to the case story of Rhonda as she is trying to sort through all of the nutritional information for each energy drink. Rhonda is trying to find out three pieces of information for each drink: (1) what is the nature of each ingredient, (2) what is the physiological role of each ingredient, and (3) which ingredients actually provide energy?

Slide 32: This clicker question asks students if caffeine is a source of energy. The correct answer should not be given as students learn in the next few slides about the role of caffeine as a stimulant. This slide provides the chemical structure of caffeine, which is considered a methylated xanthine derivative.

Slide 33 and Slide 34: Students are brought back to the case by reading how Rhonda begins her research by looking at the role of caffeine. Rhonda has learned that caffeine is a stimulant and that many energy drinks have large concentrations of caffeine in addition to other legal stimulants including guarana, which also contains more caffeine! Two other stimulants quite often found in energy drinks are theophylline and theobromine, also chemical xanthines (like caffeine). Theobromide is found in high concentrations in cocoa and chocolate; both are found in tea. Large doses of caffeine, especially when given to non-users, can produce headache, jitteriness, abnormally rapid heartbeat (tachycardia), convulsions, and even delirium.

Slide 35: Provides students with their research task. Students spend approximately 10–15 minutes in small groups (2–3 students each) analyzing and categorizing the individual biochemical ingredients for one of the energy drinks. Results for each drink are then summarized on the board for the entire class to discuss. In a large class, there will be multiple small groups preparing information for the same energy drink. Each group can be given the opportunity to revise/correct the information on the board until a larger group consensus is reached. In our experience, some student groups will make errors in categorizing ingredients, but students in the other groups will quickly recognize these errors and correct them.

Slide 36: After discussing and highlighting viable sources of energy in each drink, this clicker question is given asking students whether or not any of the drinks discussed actually provide more energy than a 12-ounce Coca Cola^®.

Slide 37, Slide 38, Slide 39, and Slide 40: These slides provide the last part of the case study. Here students are given information regarding the dangers of mixing energy drinks with alcohol—an important issue to discuss considering the growing trend toward mixing among college-aged students. A hyperlink to a video interview with Dr. Mary Claire O’Brien from Wake Forest University is shown on Slide 40; the focus of this interview is reviewing the results of a study regarding the prevalence and medical dangers of mixing energy drinks with alcohol (referenced below). From this report, students who reported consuming alcohol mixed with energy drinks had significantly higher prevalence of alcohol-related consequences, including being taken advantage of sexually, taking advantage of another sexually, riding with an intoxicated driver, being physically hurt or injured, and requiring medical treatment (p < 0.05).

Slide 41: A clicker question that asks students to reevaluate their choices regarding energy drink consumption.

Additional Notes to the Instructor

We routinely complete this entire case in a 55-minute class period. The case is used following several lectures in which the concepts of glycolysis, Krebs cycle, and electron transport/oxidative phosphorylation are covered in some detail in conventional lecture format. If this case is used in place of traditional lectures covering cellular respiration, it may be necessary to split the case over two class periods. A convenient place to interrupt the case would be between Slide 32 and Slide 33 (after covering the basics of glycolysis, Krebs cycle, and electron transport in the first class period).

Students may also wonder where re-hydrating drinks such as Gatorade^® fall into the picture of “energy drinks.” Gatorade^® is not considered a so-called energy drink and is very different in content from all of the drinks analyzed in this case. Gatorade^® contains electrolytes (potassium, sodium, and chloride), which are lost through sweating during vigorous exercise, and a 6% carbohydrate mix of glucose, fructose, and sucrose to provide fluid absorption and energy. Unlike most energy drinks, Gatorade^® does not contain any caffeine or stimulants.

It should be noted that many of the figures in the case are free images having no significant legal restrictions on use. Copyrighted textbook figures may better illustrate the components of cellular respiration. Instructors may choose to use such items in accordance with fair use guidelines if they find they are better suited to their class.

Answer Key

Answers to the questions posed in the case study are provided in a separate answer key to the case. Those answers are password-protected. To access the answers for this case, go to the key. You will be prompted for a username and password. If you have not yet registered with us, you can see whether you are eligible for an account by reviewing our password policy and then apply online or write to answerkey@sciencecases.org.

References

Ball State University. (2001) Combining Energy Drinks with Alcohol Potentially Dangerous. ScienceDaily.

http://www.sciencedaily.com/releases/2001/11/011116065754.htm

Article that describes research linking energy drink consumption to risk behavior in college-aged people.

Doheny, K. (2008) Energy Drinks: Hazardous to Your Health? Products Need Warning Labels, Scientist Says; Industry Contends They’re Safe to Drink. WebMD Health News.

http://www.webmd.com/balance/news/20080924/energy-drinks-hazardous-to-your-health?src=RSS_PUBLIC

Article regarding labeling and safety of energy drinks. The role of the FDA is discussed.

Ferreira S.E., de Mello M.T., Pompéia S., and de Souza-Formigoni M.L. (2006) Effects of energy drink ingestion on alcohol intoxication. Alcoholism: Clinical and Experimental Research 30(4):598–605.

This study evaluates the effects of the simultaneous ingestion of an alcohol and an energy drink, compared with either alcohol or an energy drink alone. Overall the authors find that the ingestion of alcohol plus energy drink significantly reduces subjects’ perception of the symptoms of alcohol consumption, i.e., headache, weakness, and impairment of motor coordination. However, the deficits caused by alcohol on objective motor coordination and visual reaction time were not changed.

Heidemann, M. and Urquhart, G. A Can of Bull. National Center for Case Study Teaching in Science.

Case: http://www.sciencecases.org/energy_drinks/energy_drinks.asp

Teaching Notes: http://www.sciencecases.org/energy_drinks/energy_drinks_notes.asp

Original case study published for use without clickers.

Malinauskas, B.M., Aeby, V.G., Overton, R.F., Carpenter-Aeby, T. and Barber-Heidal, K. (2007) A survey of energy drink consumption patterns among college students. Nutrition Journal 6:35

http://www.nutritionj.com/content/6/1/35

Survey based study of energy drink usage by college students which showed that the majority of users consumed energy drinks for insufficient sleep (67%), to increase energy (65%), and to drink with alcohol while partying (54%).

McCusker, R.R., Goldberger, B. A., and Cone, E. J. (2006) Caffeine content of energy drinks, carbonated sodas, and other beverages. Journal of Analytical Toxicology 30(2):112–114.

The caffeine content of 10 energy drinks, 19 carbonated sodas, and 7 other beverages was determined. In addition, the variability of the caffeine content of Coca-Cola^® fountain soda was also evaluated.

O’Brien M.C., McCoy, T.P., Rhodes, S.D., Wagoner, A., and Wolfson, M. (2008) Caffeinated cocktails: Energy drink consumption, high-risk drinking, and alcohol-related consequences among college students. Academic Emergency Medicine 15(5):453–60.

This is the original report that the video interview (Slide 40) references.

Smit, H.J., Cotton, J.R., Hughes, S.C., and P.J. Rogers. (2004) Mood and cognitive performance effects of “energy” drink constituents: Caffeine, glucose and carbonation. Nutritional Neuroscience 7(3):127–139.

In this study, the role of caffeine, carbohydrates, and carbonation was investigated with regard to mood and cognitive performance of individuals. Overall energy drinks were found to improve and/or maintain mood and performance during fatiguing and cognitively demanding tasks relative to placebo.

Slide Credits

Acknowledgements: This material is based upon work supported by the NSF under Grant No. DUE-0618570. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF. Additionally, the authors would like to thank Drs. Clyde F. Herreid (University of Buffalo) and Eric Ribbens (Western Illinois University) for their guidance and critical evaluation of the case.

Date Posted: January 29, 2010.

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