2. Chapter 2 Nutritional Needs
Note: This chapter covers the functions and sources of key nutrients; the effects of various nutrient deficiencies and excesses; and the processes of digestion, absorption, and metabolism. This presentation displays the text objective related to each of these topics, followed by information to help students achieve the objective.
Part 1
The Importance of Food

3. Objective
Discuss: What nutrients can you name? Why is it important to be aware of what nutrients do in your body and what foods provide them?
Name the key nutrients, describe their functions, and list important sources of each.
© 2002 Wisconsin Milk Marketing Board, Inc.

4. The Nutrients
A nutrient is a chemical substance that helps maintain the body.
You need over 50 nutrients, which can be divided into six groups.
Carbohydrates
Fats
Proteins
Vitamins
Minerals
Water
Discuss: What have you heard about the health effects of any of these nutrient groups?

5. Key Nutrient: Carbohydrates
Functions
Supply energy
Provide bulk
Help the body digest fats
Spare proteins
Discuss: Why do you need bulk in your diet? What is the value of sparing proteins?

6. Sources of Carbohydrates
Sugars—honey, jam
Fiber sources—fruits, vegetables, whole grains
Starch sources—breads, cereals, pasta
Discuss: What do the terms simple carbohydrates and complex carbohydrates mean? Which type of carbohydrates should provide most of the calories in your diet?
What is your favorite source of carbohydrates?
photo courtesy of Fleischmann’s Yeast

7. Key Nutrient: Fats Functions Supply energy Carry fat-soluble vitamins
Insulate the body
Protect organs
Provide essential fatty acids
Discuss: What functions do fats serve in foods?

8. Sources of Fats Saturated—dairy products, meats
Discuss: How do fats that are high in saturated fatty acids differ from those that are high in unsaturated fatty acids? How can you reduce the amount of saturated fats from dairy products and meats in your diet? What are some other food sources of mono- and polyunsaturated fats?
Saturated—dairy products, meats
Mono- and Polyunsaturated—fish, nuts, vegetable oils

9. Key Nutrient: Proteins
Functions
Build and repair tissues
Help body make important substances
Regulate body processes
Supply energy
Discuss: Which of these functions is also performed by other nutrients?

10. Sources of Proteins
Complete proteins—dairy products, eggs, fish, meat, poultry
Incomplete proteins—beans, grains, nuts
Discuss: Why are some sources of proteins considered to be “complete” while others are considered to be “incomplete”? What can you do to improve the nutritional value of incomplete sources of protein?
How can you find out if a food is a good source of protein?
National Chicken Council

11. Key Nutrient: Vitamins
Vitamins can be divided into two main groups.
Fat-soluble vitamins
dissolve in fats
can be stored in fatty tissues of the body
Water-soluble vitamins
dissolve in water
are not stored in the body
Note: Each vitamin performs different specific functions. In general, vitamins support normal growth, maintenance of body tissues, and reproduction. Each vitamin is also found in different food sources. Eating a variety of foods is the best way to get all the vitamins you need.

12. Fat-Soluble Vitamins Nutrient Functions Sources Vitamin A Vitamin D
Keeps skin and mucus membranes healthy
Prevents night blindness
Promotes growth
Butter, dark green and yellow fruits and vegetables, egg yolk, liver, whole and fortified milk
Vitamin D
Builds strong bones and teeth
Egg yolk; fortified butter, margarine, and milk; the sun
Vitamin E
Acts as an antioxidant to protect cell membranes
Eggs, liver, salad oils, whole grain cereals
Vitamin K
Helps blood clot
Cauliflower, egg yolk, organ meats
Note: Due to space limitations, not all functions and sources are listed. See Table 2-9 in the text for more detail.
Discuss: What advantages and disadvantages are created by the body’s ability to store fat-soluble vitamins in the fatty tissues?

13. Water-Soluble Vitamins
Nutrient
Functions
Sources
Vitamin C
Helps wounds heal
Helps fight infection
Broccoli, citrus fruits, tomatoes
Thiamin
Keeps nervous system healthy
Releases energy from food
Pork, whole grain breads and cereals
Riboflavin
Helps cells use oxygen
Breaks down carbohydrates
Cheese, eggs, milk, poultry
Niacin
Helps cells use other nutrients
Dried beans and peas, peanuts
Folate
Helps protect brain and spinal cord of unborn babies
Bananas, fortified breads and cereals
Note: Due to space limitations, not all functions and sources are listed. See Table 2-13 in the text for more detail. Other B-complex vitamins include vitamin B6, vitamin B12, pantothenic acid, and biotin.
Discuss: What other nutrients are provided by the food sources of each of these vitamins?

14. Key Nutrient: Minerals
Minerals can be divided into two main groups.
Macrominerals are needed in amounts of 100 mg or more per day.
Trace elements are needed in amounts less than 100 mg per day.
Note: Each mineral performs different specific functions. In general, minerals become part of the bones, soft tissues, and body fluids and help regulate body processes. Each mineral is also found in different food sources. Eating a variety of foods is the best way to get all the minerals you need.
Discuss: What is another name for trace elements?

15. Macrominerals Nutrient Functions Sources Calcium Magnesium Phosphorus
Builds bones and teeth
Helps muscles and nerves work
Dairy products, leafy green vegetables
Magnesium
Helps cells use energy nutrients
Regulates body temperature
Beans, dark green leafy vegetables, whole grains
Phosphorus
Regulates bodily activities
Protein and calcium food sources
Sodium, chloride, potassium
Control osmosis
Maintain acid-base balance in the body
Sodium and chloride: Table salt
Potassium: Potatoes
Note: Due to space limitations, not all functions and sources are listed. See Table 2-16 in the text for more detail.
Discuss: Why is it especially important for teens to get adequate sources of calcium in their daily diets? What is the largest source of sodium and chloride in the U.S. diet?

16. Trace Elements Nutrient Functions Sources Fluorine Iodine Iron Zinc
Helps teeth resist decay
Maintains bone health
Fluoridated drinking water, toothpaste
Iodine
Promotes normal function of thyroid gland
Iodized table salt, saltwater fish and shellfish
Iron
Helps cells use oxygen
Dried beans and fruits, egg yolk, lean meats, whole grains
Zinc
Helps wounds heal
Promotes normal growth
Legumes, meat, poultry, seafood, whole grains
Note: Due to space limitations, not all functions and sources are listed. See Table 2-18 in the text for more detail. Other trace elements include copper, selenium, and manganese.
Discuss: Because they are needed in smaller amounts, do you think trace elements are less important for good health than macrominerals? Explain why or why not.

17. Key Nutrient: Water Functions
Aids digestion and cell growth and maintenance
Facilitates chemical reactions
Lubricates joints and cells
Regulates body temperature
Discuss: What factors would increase a person’s need for water?

18. Sources of Water Liquids Food Breakdown of energy nutrients
Discuss: What types of foods would have high water content?
Which source do you think provides most of your water needs?
Agricultural Research Service, USDA

19. Objective
Discuss: Why is it important to consume the right balance of the various nutrients?
Analyze the effects of various nutrient deficiencies and excesses.

20. Nutrient Deficiencies
Failure to get a sufficient amount of a nutrient may result in an illness called a deficiency disease.
Such diseases include
protein-energy malnutrition (protein)
night blindness (vitamin A)
rickets (vitamin D)
scurvy (vitamin C)
osteoporosis (calcium)
Discuss: What other nutrient deficiency diseases can you name?

21. Nutrient Excesses
Discuss: If nutrients are good for you, why wouldn’t consuming more of them always be better for you?
Excess energy nutrients—carbohydrates, fats, and proteins—can lead to unhealthful weight gain.
Excesses of some vitamins and minerals can lead to toxicity (poisoning) and other complications.

22. Apply It! Your grandmother has been diagnosed with osteoporosis.
Discuss: What steps can you take now to avoid developing osteoporosis as you age?
What is the likely cause of this affliction? What health effects may your grandmother suffer as a result of this disease?

23. Objective
Discuss: What can you do to help your body digest foods and use the nutrients they provide?
Explain the processes of digestion, absorption, and metabolism.

24. The Digestion Process
Digestion is the bodily process of breaking food down into simpler compounds the body can use.
The mechanical phase involves the physical breakdown of food caused by chewing and muscle activity in the digestive tract.
The chemical phase involves the chemical breakdown of food caused by enzymes in saliva and digestive juices.
Discuss: What parts of your body are involved in the digestion process?

25. The Absorption Process
Absorption is the process of taking in nutrients and making them part of the body. A large surface area in the small intestine allows tiny nutrient particles to pass into the blood and lymph systems and travel where needed.
Discuss: How must carbohydrates, fats, and proteins be broken down before the body can absorb them?
What would happen if your body were unable to absorb the nutrients you consumed through foods?

26. Metabolism
Metabolism is the chemical processes that take place in the cells after the body absorbs nutrients.
Carbohydrates are converted into glucose for use as an energy source.
Fatty acid chains from fats are shortened and fats are used for fuel.
Amino acids from proteins are used for maintenance, growth, production of enzymes and antibodies, and energy.
Discuss: What roles do vitamins, minerals, and water play in metabolism?

27. What are your nutritional needs?
Key Question
Note: Encourage students to use this question to help them review chapter information and apply it to their lives.
What are your nutritional needs?

28. Other Questions to Consider
Discuss: What other questions did this chapter raise that you would like to explore?
What role should dietary supplements play in meeting nutrient needs?
What is cholesterol and why is it a nutritional concern?