chapter
THE NUTRIENTS
SECTION 2.1 The Role of Nutrients SECTION 2.2 Carbohydrates, Fibers, and Proteins SECTION 2.3 Fats SECTION 2.4 Vitamins, Minerals, and Water SECTION 2.5 How Your Body Used Food
YOU NEED
Section 2.2
Carbohydrates, Fiber, and Protein As you read in section 2.1, for good health you need six basic nutrients, plus fiber. Read on to learn more about these, beginning with carbohydrates, fiber, and proteins.
Carbohydrates The body’s main source of energy is carbohydrates. You may know them as starches and sugars. They are found mainly in foods from plant sources, such as fruits, vegetables, grain products, and dry beans and peas. For good health, eat a variety of these foods every day. Generally, they are the least expensive form of energy you can buy If you don’t eat enough carbohydrates, your body will use the other energy producing nutrients for energy. When it does, however, it keeps those nutrients from doing their specialized jobs. Carbohydrates include starches, natural sugars, and refined sugars.
Grain products, dry beans and peas, and fruits and vegetables are important sources of carbohydrates. The starches and sugars they contain provide energy for the body.
Starches
Natural Sugar
Refined Sugar
Starches are also known as complex car- bohydrates. They are found in dry beans, peas, and lentils; vegetables, such as pota- toes and corn; and grain products, such as rice, pasta, and breads. These foods are also good sources of proteins, vitamins, minerals, and dietary fiber.
Sugars, also called simple carbohydrates, are a natural part of many foods. There are several types of natural sugars. Fructose (MALL-tohs) in grain products, and lactose (LACK-tohs) in milk. These foods also pro- (FROOKtohs) is found in fruits, maltose vide other nutrients, such as proteins, vita- mins, and minerals.
Refined sugars are sugars that are removed from plants and used as sweeten- ers. Sucrose (SUE-krohs), or table sugar, comes from plants such as sugar cane or sugar beets. It is used as a sweetener in many foods, such as desserts and candy Other refined sugars include corn syrup, honey, maple syrup, molasses, and brown sugar Studies show that refined sugar does not directly pose any health risk. It can, however, which can contribute to health problems. other than simple carbohydrates. To meet your energy needs, rely on the starches and natural sugars found in vegetables, dry lead to tooth decay. Eating large amounts of sweetened foods can lead to excess weight, Refined sugar does not supply nutrients beans and peas, fruits, and grain products.
SCIENCE CONNECTION Carbohydrates get their name from their chemical structure. They are composed of the elements carbon, oxygen, and hydro- gen. Simple carbohydrates (sugars) are made up of single or short chemical units. Complex carbohydrates (starches) are made up of long chemical units.
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Dietary Fiber As you learned in section 2.1, dietary fiber consists of plant materials that are not digested. Fiber is found only in foods from plant sources, such as fruits, vegetables, grain products, and dry beans and peas. Foods from animal sources do not contain fiber. There are two kinds of fiber. Most plant foods contain different amounts of both. Insoluble fiber will not dissolve in water. It absorbs water and contributes bulk. It helps food move through the large intestine at a normal rate. It promotes regular bowel movements and helps prevent constipation. This type of fiber appears to lower the risk of colon cancer. It is found mainly in fruit and vegetable skins and in whole wheat or wheat bran products.
Soluble fiber dissolves in water. It does not contribute bulk. Studies show it appears to lower blood cholesterol levels. Soluble fiber is found in fruits; vegetables; dry beans, peas, and lentils; and oat products. The National Cancer Institute recommends 20 to 35 grams of dietary fiber a day. To make sure you get enough fiber, eat a wide variety of plant foods such as fruits, vegetables, and whole grain products every day. Increase the fiber gradually and be sure to drink enough liquids. You might develop diges tive problems, such as abdominal cramps.
Protein Proteins are used mainly to help the body grow and to repair worn-out or damaged parts. About one-fifth of your body’s total weight is protein. Your hair, eyes, skin, muscles, and bones are made of protein. The proteins you eat help maintain them in good condition. Proteins also regulate important body processes. For instance, they play a major role in fighting disease because parts of the immune system are proteins. Proteins can do their job only if the body has enough carbohydrates and fats for energy. If not, the body
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uses proteins for energy instead of for building and repairing protein than they need. Excess amounts are Proteins are found in all foods from animal sources, such as meat, poultry, fish, eggs, and dairy products. They are also found in foods from plant sources, especially dry beans and peas, peanuts, vegetables, and grain products. Most Americans eat more stored by the body as fat.
Complete and Incomplete Protein Protein is made up of chemical com- pounds called amino acids (uh-MEE-no) There are about 22 different amino acids. They can be combined into millions of different kinds of protein. The body can manufacture most of the amino acids it needs to build protein. However, nine amino acids cannot be made in the body and therefore must come from the food you eat. These nine amino acids are called essential amino acids. Complete proteins supply all of the essential amino acids. Foods from animal sources, such as meat, poultry, fish, eggs, and dairy products, provide complete protein. Incomplete proteins are lacking one or more essential amino acids. Foods from plant sources supply incomplete proteins. However, it’s possible to obtain all of the essential amino acids by eating a variety of foods from plant sources.
For example, dry beans and peas are high in proteins, but they lack certain essential amino acids. Grain products, nuts, and seeds also lack some essential amino acids. How- ever, they provide the ones that dry beans and peas lack. If dry beans or peas and any grain products, nuts, or seeds are eaten dur- ing the same day, they provide all the essential amino acids needed for good health. Each supplies what is missing from the other Most Americans get the largest amount of their protein from animal sources. Health experts recommend that people get more of their protein from plant sources. Why? Plant sources have less fat, and low-fat food choic- es are recommended. You will learn more about fat in the next section.
SECTION 2.2 REVIEW Recall the Facts 1.
2.
3.
WORLD OF VARIETY Many dishes from around the world make use of plant proteins. For instance, meals in India often include dal, lentils cooked and seasoned in a variety of ways. Dal is often served with rice, a combination that provides complete proteins.
List three foods that supply natural sugars and six foods that supply complex carbohydrates. Why is it important to obtain both soluble and insoluble fiber? What is the difference between complete and incomplete proteins?
Discuss Your Ideas 4.
In general, Americans eat more refined sugar than is needed for good health. What are some possible reasons?
Apply Your Learning 5.
Think back to the last meal you ate. Which foods supplied carbohydrates? Fiber? Proteins? What types of carbo- hydrates, fiber, and proteins were they?
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Section 2.3
Fats Fats are in the news a great deal these days. You may have heard or read about cut- ting down on fats. That’s sound advice, as you will see. However, even health experts do not recommend that you avoid fats altogether. This section will help you understand fat’s role as a nutrient.
Function and Sources of Fats Fat is an essential nutrient that has several important functions. You need some fat in your diet for healthy skin and normal growth. Your body needs certain substances called essential fatty acids, which are found mainly in vegetable oils. Fat in the body carries vitamins A, D, E, and K to wherever they are needed. In addition, the body stores fat to provide a reserve supply of energy. This stored fat also acts as a cushion to protect vital organs such as the heart and liver. Fats also add flavor to food. Because they move through the digestive system slowly, they have satiety (suh-TIE-uh-tee) value. In other words, your hunger remains satisfied for a longer time if you eat foods that include some fat. The problem with fat is that most people eat too much. Eating too much fat increases the risk of illnesses such as heart disease and cancer. It can also create a health risk by causing the person to become overweight. (Remember, fats have twice as many calories.
Foods high in fat include butter, mar as carbohydrates or proteins.) garine, oils, cream, sour cream, salad dress fried foods, some baked goods, and chocolate. Large amounts are also found in some cuts of meat, nuts and seeds, peanut butter, egg yolk, whole milk, and some cheeses. Fats cannot be eliminated from the diet completely. However, it is important to mod erate, or limit, their use. To cut down on fat, eat more complex carbohydrates and choose low-fat foods. You will learn more about making food choices in Chapters 3 and 4. Health experts also advise people to pay attention to the types of fats that are eaten. As you will soon discover, some fats create more of a health risk.
Oil, butter, and margarine are obvious sources of fat. However, many other foods also contain hight amounts of fats.
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Cholesterol, Fats, and Health “My dad is watching his cholesterol.” “Brand X oil is high in polyunsaturates.” Statements like these can be heard frequently. What does it all mean?
Cholesterol in The Bloodstream Cholesterol (kuh-LESStehr-all) is a fat- like substance present in all body cells. It is needed for many essential body processes. Your body manufactures cholesterol in the liver. A certain amount of cholesterol circulates in the blood. It does not float through the Alt bloodstream on its own, but in chemical “packages” called lipoproteins (LIH-po-PRO- teens). There are two major kinds of lipoproteins: LDL and HDL. LDL stands for low-density lipoprotein. The LDL “package” takes cholesterol from the liver to wherever it is needed in the body. However, if too much LDL choles- terol is circulating, excess amounts of cholesterol can build up in artery walls. This increases the risk of heart disease or stroke. Thus, LDL cholesterol has come to be called “bad” cholesterol. HDL stands for high-density lipoprotein. Studies suggest that HDL picks up excess cholesterol and takes it back to the liver, keeping it from causing harm. For this reason, cholesterol in the HDL “package” has come to be known as “good” cholesterol.
Medical tests can determine the amounts of total cholesterol, LDL cholesterol, and HDL cholesterol in the bloodstream. The risk of heart disease is believed to increase if LDL and total cholesterol levels are too high and if the HDL level is too low Making wise food choices can help reduce the amount of harmful cholesterol in the bloodstream. As you will see, both choles- terol and fat in foods may affect blood cholesterol levels.
High levels of cholesterol in the bloodstream can increase the risk of heart disease or stroke. Foods from animal sources contain cholesterol. Limiting how often they are eaten can help reduce cholesterol levels in the blood.
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Cholesterol in Foods In addition to being manufactured in the body, cholesterol is found in some foods. Cutting down on high-cholesterol foods may help reduce the level of harmful cholesterol in the bloodstream. Cholesterol is found only in foods from animal sources. Meat, poultry, and fish all have about the same amount of cholesterol. Foods especially high in cholesterol include liver, egg yolks, and a few types of shellfish.
Foods such as fish, poultry, and meat contain saturated fats. Polyunsaturated and monounsaturated fats are found irn vegetable oils and foods such as peanuts, olives and avocados.
Saturated and Unsaturated Fats For most people, the amount and types of fats eaten have an even greater effect on blood cholesterol levels. The different fats found in food, such as butter, chicken fat, or corn oil, are made up of different combinations of fatty acids. There are three basic kinds of fatty acids. The different fats found in food, such as butter, chicken fat, or corn oil, are made up of different combinations of fatty acids. There are three basic kinds of fatty acids. Each has different effect on cholesterol levels. All fats include all three kinds of fatty acids, but in varying amounts. Saturated (SAT-chur-ay-ted) fatty acids appear to raise the level of LDL (“bad”) choes-
terol in the bloodstream. Foods relatively high in saturated fatty acids include meat poultry skin, whole-milk dairy products, and the tropical oils, coconut oil, palm oil, and palm kernel oil. Polyunsaturated (PAH-leeuhn-SAT- chur-ay-ted) fatty acids seem to help lower both HDL and LDL cholesterol levels. Many vegetable oils, such as corn oil, soybean oil, and safflower oil, are high in polyunsaturated fatty acids. Monounsaturated (MAH-no-uhn-SATchur-ay-ted) fatty acids appear to lower only LDL (“bad”) cholesterol levels. Foods rela tively high in monounsaturated fatty acids include olives, olive oil, avocados, peanuts peanut
oil, and canola oil. In general, a fat that is solid at room temperature, such as butter or lard, has mainly saturated fatty acids. Fats that are liquid at room temperature, such as vegetable oil, have mainly unsaturated fatty acids. Vegetable oils can be made solid through a process called hydrogenation (hi-DRAHjuh-NAY-shun). Shortening and margarine are examples of hydrogenated fats. The hydrogenation process makes the fat more saturated. Many people are switching from saturated fats to unsaturated ones in an effort toward better health. They should remember, however, that it’s also important to limit the total amount of all fat eaten.
HEALTHY ETITUDE Besides eating less fat and cholesterol here are some other health habits that can help lower blood cholesterol levels: Eat plenty of soluble fiber (the kind found in dry beans and oats). Exercise regularly . Maintain a healthy weight. Don’t smoke.
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4
chapter
PLANNING DAILY
SECTION 4.1 Daily Meals and Snacks SECTION 4.2 Improving Your Eating Habits SECTION 4.3 Eating Out Nutritiously SECTION 4.4 Vegetarian Food Choices
FOOD CHOICES
Section 4.1
Daily Meals and Snack Barry greeted his friend at the door. “Hi, Manuel. I’m glad you stopped by. We were just sitting down to dinner-would you like to join us?” “I’m sorry, I didn’t know you hadn’t eaten yet,” said Manuel. “I’ve already had supper.” “Well, then, how about a snack?” Barry grinned. “Come on in!” Has something similar ever happened to you? Because of differences in schedules family background, and habits, people followw different patterns when it comes to meals and snacks.
Eating Pattern The term eating patterns refers to when, what, and how much people eat. Today, many different eating patterns are becoming common. Some people eat three traditional small meals. People often eat snacks between meals. Some use different eating smali meais ic others piefer to eat many patterns from day to day, depending on their the midday meal, and the evening meal schedules. No matter what your eating pattern is, the goal is to make nutritious food choices BreakFast throughout the entire day. It’s also important to eat regularly. If you try to go too lon without food, your body won’t have the fuel th it needs.
Eating breakfast makes a different in how you feel all morning. Any of these nutritious choices can give your body fuel for a morning of activity.
HEALTHY ETITUDE
Traditional Meals The traditional meals include breakfast, the midday meal, and the evening meals.
Breakfast Studies show that people who skip haven’t eaten since the even inue to prove that breakfast is e most important meal of the day. You meals make up for it by overeating later. which means your body hasn’t had a supply Usually, meal skippers eat more in a day of energy foods for many hours. Breakfast than they would if they chose to eat at regu gives you energy and helps you feel alert lar intervals. during the morning hours If you skip breakfast, it’s harder to concen- trate on your schoolwork. Recent studies show that students who eat breakfast get to school on time and score better grades thar those who don’t eat breakfast. Not all breakfasts are equal. A breakfast of starch, protein, and fruit, such as whole
grain cereal or muffin, milk, and banana, gives you more lasting energy than a dough- nut and a soft drink. You may feei fine after eating the doughnut and soft drink, but you will probably experience a mid-morning let- down Some people skip breakfast because they are bored with standard breakfast fare. How- ever, any food can be breakfast food, so long as it is nutritious. Try having pizza, tacos, soup with crackers, or refried beans on toast for breakfast. Round out the menu with a serving of fruit and low-fat milk.
Are you a breakfast skipper? If time is your probiem, begin by getting up a few minutes earlier. Make a meal out of “quick” foods, such as: Low-fat flavored or plain yogurt, whole grain muffin or bagel, and a banana. Peanut butter and jelly sandwich and low-fat milk. A breakfast drink made by blending lowfat milk or yogurt, juice, and fruit.
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Midday and evening Meals The midday meal gives you energy and nutrients to carry out the rest of the day’s activities. The evening meal is a good time to think about the food you’ve eaten for the day. It’s your chance to fill in any food group servings that are lacking. “Dinner” traditionally means the largest meal of the day. It may be eaten at midday or in the evening , depending on your personal preference and your schedule. Some people prefer to eat dinner at mid- day and a lighter meal, sometimes called supper, in the evening. The larger midday meal provides fuel for the day’s activities. Some people find they sleep better if the evening meal is light.
On the other hand, sometimes people pre- fer to have a light meal, or lunch, at midday. This pattern is often chosen by those who work or go to schooi. They may prefer to have the largest meal in the evening when all or most family members can eat together. On weekends or special occasions, they may follow a different pattern. No matter when it is eaten, a dinner usually includes a main dish along with a grain prod uct, vegetables, and a beverage. Sometimes people add dessert. A typical dinner might be stir-fried chicken, broccoli, and water chest-
nuts over rice; a tossed salad; low-fat milk; a whole wheat roll; and fruit for dessert. For a lighter lunch or supper, popular choices include sandwiches, soups, main- dish salads, and similar foods. Accompani- ments could include fresh fruits and vege- tables, whole grain bread, and low-fat milk or yogurt.
Snacks Snacks are small amounts of food eaten between meals. Snacking is not necessarily a bad habit. Well-chosen snacks can help you meet your energy and nutrient needs throughout the day. However, many socalled “snack foods” are high in fat, sugar, and calories. These include candy, chips, granola, cookies, and other sweets. For a nutritious snack, you can choose almost any nutrient-dense food from the five food groups. Try leftovers from the fresh fruits or vegetables, low-fat dairy products, or whole grain breads and cereals.
WORLD OF VARIETY In Mexico, the main meal is eaten at midday. A light meal or snack, called merienda, may be eaten in the early evening, followed by supper in the late evening.
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Also consider the timing of your snacks. If you snack too close to mealtime, you may not be able to eat the nutritious foods included in the meal. Remember that snacks are as much a part of your eating pattern as breakfast, lunch, or dinner. Choose them wisely.
When you choose snacks, consider nutrient density. Snacks like thoose shownn at the left can satisfy your hunger and profide important nutrients. The snack shown the right are high in fat, sugar, sodium, and calories. Which snacks do you choose most often?
"Grazzing" Some people prefer to eat five or more small meals throughout the day instead of three larger ones. This eating pattern is sometimes called “grazing.” If grazing is your eating pattern, think about your food choices toward the end of the day. Are you lacking any servings from the food groups? If so, eat those foods so you’ll be sure to meet the daily On the other hand, check to be sure you are not eating too much The day’s total servings and calories should be the right amount for you, just as if you were eating three traditional meals.
As you have learned, eating patterns vary from person to person and day to day. In the end, when you eat is less important than what you eat. The eating pattern that helps you get the nutrients you need and the right number of calories is the one that’s best for you. Identifying your eating pattern can help you plan for good nutrition.
SECTION 4.1 REVIEW Recall the Facts 1. 2. 3.
Give three examples of different eating Why is breakfast considered the most How can you choose snacks that help patterns. important meal of the day? meet your nutrient needs?
Why might people prefer smaller meals more often instead of three larger meals?
Discuss Your Ideas 4.
5.
What eating pattern do you usually fol- low? How does it reflect your lifestyle? What are some advantages of grazing? What are the disadvantages?
Apply Your Learning 6.
Make a list of 15 nutritious snack foods that require little preparation. Put a check mark by those you have tried before. Put a star by those you plan to try
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Section 4.2
Improving Your Eating Habits If you are like most people, some of your eating habits are healthful ones. Others, however, could be improved. The first step in improving your eating habits is to recognize the kinds of food choices you make now . Then you can keep your good habits and work on improving the poor ones.
What Are You Current Habits? People sometimes aren’t aware of how often and what they eat. They may make sound food choices at certain times or in some situations, but not others. You can become more aware of your habits by keeping a food record. This is simply a list of all the food you eat for a spe- cific period of time. Start by carrying a small notebook or scratch pad with you. Each time you eat, no matter how small the amount, me make a note in your record.
Write down: The time you ate. The food eaten and the amount. You don’t have to measure the exact amountjust a make a reasonable estimate. A brief description of the eating situation. This might include where you were, what you were doing, your mood, and any ther information that could help you understand your food habits.
Keep your food record for three consecutive days, including at least one weekend day. During this time, make your usual food choices. This is not a test you have to pass. It’s just a way of letting you know the kind of food choices you are making now.
Reviewing Your Food Record At the end of the three-day period, take a look at your food choices. For each day count the number of servings you had from each group in the Food Guide Pyramid (page 97). Compare your totals with the recommended number of servings. Did you eat at least the minimum amount of servings? If not, which foods were you lacking? Were your food choices high or low in fats and added sugars? Remember, fats, oils, and sweets should be eaten sparingly
In Shopping malls, tempting foods seem to be everywhere. Look for nutritious choices.
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How Can You Improve Your Habits? Perhaps your food record shows that you are already following the Food Guide Pyramid and the Dietary Guidelines. If so, keep up your good habits. Most people, however, find that their food choices leave room for improvement. For instance, Roberto discovered that he was noteting enough vegetables. He also saw that high-fat and sugary foods were often among his food choices. Once you have identified poor eating habits, think about why they occur. Look at your food record again. Did you tend to make poor food choices in certain situations, such as while watching TV or when you were unhappy? Roberto’s food record showed that he often snacked on cookies or french fries when he was at the mall with friends.
Next, think about how to solve the problem. Some people just tell themselves, “I’ll eat better from now on.” That promise is hard to keep because it isn’t specific. Instead decide on specific changes you can make (You may want to review the decision making steps explained in Section 1.5.) The next time he went to the supermarket Roberto noticed how many different kinds of fresh vegetables there were. He decided to try at least one new vegetabie a week. After he had done this for several weeks, he began to work on choosing healthier snacks at the mall.
Remember, eating is an enjoyable part of life. Don’t take the pleasure out of it. You can make changes in your food habits and have fun doing it. Every once in a while, keep another food record for several days. Use the same method to analyze your food choices. Compare it to your previous food record. You can see if you are making the necessary changes that will help you feel and look better. Keeping a food record and analyzing your food choices can help you stay on the track toward good health.
SECTION 4.2 REVIEW Recall the Facts 1.
TIPS FOR SUCCESS Developing New Eating Habits Begin to make changes in your food habits gradually. Work on them one by one Allow plenty of time for each new way of eating to become a habit. If you find yourself slipping back into old ways of eating, don’t give up. Review your plan and make sure it’s realistic, then try again. If you continue to make the effort, eventually you will succeed.
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2.
3.
What is a food record? What is its purpose? When keeping a food record, what information do you need to write down? Give two tips for successfully changing one’s eating habits.
Discuss Your Ideas 4.
How could you give encouragement to a friend who is working on new eating habits?
Apply Your Learning 5.
The text describes two specific steps Roberto decided to take to improve his eating habits. List at least five other steps that could help him reach his goals.