2Chapter 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 1The Importance of Food
4The NutrientsA nutrient is a chemical substance that helps maintain the body.You need over 50 nutrients, which can be divided into six groups.CarbohydratesFatsProteinsVitaminsMineralsWaterDiscuss: What have you heard about the health effects of any of these nutrient groups?
5Key Nutrient: Carbohydrates FunctionsSupply energyProvide bulkHelp the body digest fatsSpare proteinsDiscuss: Why do you need bulk in your diet? What is the value of sparing proteins?
6Sources of Carbohydrates Sugars—honey, jamFiber sources—fruits, vegetables, whole grainsStarch sources—breads, cereals, pastaDiscuss: 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
7Key Nutrient: Fats Functions Supply energy Carry fat-soluble vitamins Insulate the bodyProtect organsProvide essential fatty acidsDiscuss: What functions do fats serve in foods?
8Sources 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, meatsMono- and Polyunsaturated—fish, nuts, vegetable oils
9Key Nutrient: Proteins FunctionsBuild and repair tissuesHelp body make important substancesRegulate body processesSupply energyDiscuss: Which of these functions is also performed by other nutrients?
10Sources of ProteinsComplete proteins—dairy products, eggs, fish, meat, poultryIncomplete proteins—beans, grains, nutsDiscuss: 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
11Key Nutrient: Vitamins Vitamins can be divided into two main groups.Fat-soluble vitaminsdissolve in fatscan be stored in fatty tissues of the bodyWater-soluble vitaminsdissolve in waterare not stored in the bodyNote: 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.
12Fat-Soluble Vitamins Nutrient Functions Sources Vitamin A Vitamin D Keeps skin and mucus membranes healthyPrevents night blindnessPromotes growthButter, dark green and yellow fruits and vegetables, egg yolk, liver, whole and fortified milkVitamin DBuilds strong bones and teethEgg yolk; fortified butter, margarine, and milk; the sunVitamin EActs as an antioxidant to protect cell membranesEggs, liver, salad oils, whole grain cerealsVitamin KHelps blood clotCauliflower, egg yolk, organ meatsNote: 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?
13Water-Soluble Vitamins NutrientFunctionsSourcesVitamin CHelps wounds healHelps fight infectionBroccoli, citrus fruits, tomatoesThiaminKeeps nervous system healthyReleases energy from foodPork, whole grain breads and cerealsRiboflavinHelps cells use oxygenBreaks down carbohydratesCheese, eggs, milk, poultryNiacinHelps cells use other nutrientsDried beans and peas, peanutsFolateHelps protect brain and spinal cord of unborn babiesBananas, fortified breads and cerealsNote: 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?
14Key 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?
15Macrominerals Nutrient Functions Sources Calcium Magnesium Phosphorus Builds bones and teethHelps muscles and nerves workDairy products, leafy green vegetablesMagnesiumHelps cells use energy nutrientsRegulates body temperatureBeans, dark green leafy vegetables, whole grainsPhosphorusRegulates bodily activitiesProtein and calcium food sourcesSodium, chloride, potassiumControl osmosisMaintain acid-base balance in the bodySodium and chloride: Table saltPotassium: PotatoesNote: 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?
16Trace Elements Nutrient Functions Sources Fluorine Iodine Iron Zinc Helps teeth resist decayMaintains bone healthFluoridated drinking water, toothpasteIodinePromotes normal function of thyroid glandIodized table salt, saltwater fish and shellfishIronHelps cells use oxygenDried beans and fruits, egg yolk, lean meats, whole grainsZincHelps wounds healPromotes normal growthLegumes, meat, poultry, seafood, whole grainsNote: 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.
17Key Nutrient: Water Functions Aids digestion and cell growth and maintenanceFacilitates chemical reactionsLubricates joints and cellsRegulates body temperatureDiscuss: What factors would increase a person’s need for water?
18Sources 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
19ObjectiveDiscuss: Why is it important to consume the right balance of the various nutrients?Analyze the effects of various nutrient deficiencies and excesses.
20Nutrient Deficiencies Failure to get a sufficient amount of a nutrient may result in an illness called a deficiency disease.Such diseases includeprotein-energy malnutrition (protein)night blindness (vitamin A)rickets (vitamin D)scurvy (vitamin C)osteoporosis (calcium)Discuss: What other nutrient deficiency diseases can you name?
21Nutrient ExcessesDiscuss: 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.
22Apply 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?
23ObjectiveDiscuss: What can you do to help your body digest foods and use the nutrients they provide?Explain the processes of digestion, absorption, and metabolism.
24The Digestion ProcessDigestion 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?
25The 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?
26MetabolismMetabolism 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?
27What are your nutritional needs? Key QuestionNote: Encourage students to use this question to help them review chapter information and apply it to their lives.What are your nutritional needs?
28Other 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?