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An Internet WebQuest

PHYTOCHEMICALS AND A HEALTHY DIET

Introduction

In this WebQuest, students do some Internet research on phytochemicals and a healthy diet. They learn what phytochemicals are, the types of foods that contain important phytochemicals, and what the health benefits are for each type of phytochemical. Students discover the importance of including several servings of fruits and vegetables in their daily diet. Finally, they compile the information gathered in a table, then answer several questions about phytochemicals and a healthy diet.

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Task

Students will complete a table that lists the phytochemicals found in foods or groups of foods as they explore the Internet sites given. Each web site has some of the information they will need to complete the table, but several of the foods listed are discussed on more than one web site. Students should be able to fill in the information requested for the ten foods listed in the table. From their Internet research, students should also be able to answer the questions given.

Objectives

  • Define the word phytochemical and explain the importance of phytochemicals in a healthy diet.

  • Identify the phytochemicals that are found in a variety of fruits and vegetables.

  • Discuss the health benefits of eating natural foods that contain phytochemicals.

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Resources

Students will use the Internet links given to find out about phytochemicals and their health benefits. They will learn which foods contain which phytochemicals, and what phytochemicals have been proven to provide health benefits. They will find out if cooking destroys these health benefits, and if taking phytochemicals in pill form provides the same health benefits as eating the food directly. Finally, students with complete a table and answer a set of questions to demonstrate what they have learned regarding phytochemicals and a healthy diet.

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Time

1 class period for research, filling in the table, and answering a few questions

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Process

As students progress through the list of web sites, you may help them to focus on what they need to know to fill in the table and answer the questions. Several of the web sites have links to other web sites with relevant information. If time allows, you may want to allow students to explore this subject further. Student tables may look different from the table given here; check on student work to make sure they have listed the correct phytochemicals and health benefits or diseases treated for each food or food group.

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Evaluation

Evaluation of student work will depend upon the extent of the material listed in their tables. Students must have at least five active volcanoes listed in their tables and identified on their maps. However, students may have more than five listings; additional listings may add points to their total score as long as other criteria have been met. Make sure that the volcanoes listed can be found along the ring of fire where the Pacific Plate converges with other tectonic plates. Once students have completed the table, you may wish to use the rubric below for scoring their work. The rubric is based on five volcanoes in the table.

Food Phytochemical(s) Health Benefit/Disease Treated
Broccoli, cauliflower indoles, isothiocyanates, sulfaforaphane, thiols triggers enzyme systems to block or suppress cellular DNA damage; reduces size of cancer tumors; fights breast cancer

Garlic

ajoene, diallyl sulfide enhances immune system; increases production of enzymes that help excrete carcinogens; decreases tumor size; reduces serum cholesterol levels
Onions allylic sulfides enhances immune system; increases production of enzymes that help excrete carcinogens; decreases tumor size; reduces serum cholesterol levels
Citrus fruits monoterpenes, carotenoids, flavonoids anti-inflammatory and antitumor activity; anticoagulants; protects eyes from macular degeneration
Tomatoes, peppers lycopene protects against heart disease, protects against some forms of cancer
Grapes, berries, cherries, apples, cantaloupes ellagic acid, phenols, flavonoids enhances immune system; protects against some forms of cancer
Soybeans, beans, oats, seeds, whole grains, brown rice flavonoids, phytic acid, saponins reduces cholesterol; protects against breast and ovarian cancer; antioxidants; starves tumors by restricting growth of new blood vessels to supply tumor; protects against heart disease
Licorice root, green tea glycyrrhizm catechins protects against cancer; protects against heart disease

Spinach

lutein, zeaxanthin protects eyes against macular degeneration
Ginkgo biloba terpene lactones improves cognitive functioning; improves functioning of Alzheimer's disease patients

 

Questions about Phytochemicals and a Healthy Diet

  1. cancer, diabetes, cardiovascular disease, hypertension
  2. According to scientific studies, cooking does not destroy the phytochemicals in foods. In fact, in some cases cooking enhances the effects of the phytochemicals.
  3. According to scientific studies, taking phytochemicals in pill form does NOT provide the same health benefits as eating the food itself. Perhaps this is because each food contains many phytochemicals and some of these may work together to provide the health benefit in ways not yet understood.

Once students have completed the table and answered the questions, you may wish to use the rubric below for scoring. The rubric is based on ten foods or food groups listed in the table.

Table and Map
Rubric
Possible
Points*

Self-
Assessment

Teacher
Assessment
Each food or group has at least one phytochemical listed 10    

Each food or group has at least one health benefit or disease treated listed

10    

Information correct for each phytochemical listed

10    

Information correct for each health benefit/disease treated listed

10    
Answers to three questions correct 10    
Total Possible Points 50    

*Rate each category according to the following scale: Excellent 9-10 points; Very Good 7-8 points; Good 5-6 points; Satisfactory 3-4 points; Poor 1-2 points; and Unsatisfactory 0 points.

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Conclusion

Students should be able to fill in the table and answer the questions given. Students should also be able to answer the question about what changes they should make in their diets to protect themselves from cardiovascular disease and cancer. Students should be able to support the data in their tables and their answers to questions with information gathered in their Internet research.

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