Unsaturated lipids are found mainly in plant foods, such as vegetable oil, olive oil, and nuts. Unsaturated lipids are also found in fish such as salmon. Unsaturated lipids are needed in small amounts for good health because your body cannot make them. Most lipids and fats in your diet should be unsaturated.
Another type of lipid is called trans fat. Trans fat is manufactured and added to certain foods to keep them fresher for longer. Foods that contain trans fats include cakes, cookies, fried foods, and margarine. Eating foods that contain trans fats increases the risk of heart disease. You should do your best to eat fewer foods that contain it. Beginning in 2010, California will ban trans fats from restaurant products, and, beginning in 2011, from all retail baked goods.
Vitamins and Minerals
Vitamins and minerals are also nutrients. They do not provide energy. However, they are needed for good health.
Vitamins
Vitamins are substances that the body needs in small amounts to function properly. Humans need 13 different vitamins. Some of them are listed in Table (below) . The table also shows how much of each vitamin you need each day. Vitamins have many roles in the body. For example, Vitamin A helps maintain good vision. Vitamin B9 helps form red blood cells. Vitamin K is needed for blood to clot when you have a cut or other wound.
Vitamins Needed For Good Health Vitamin One Reason You Need It Some Foods that Have It How Much of It You Need Each Day (at ages 9–13 years)
Vitamin A Needed for good vision Carrots, spinach, milk, eggs 600 μg (1 μg = 1 x 10-6 g)
Vitamin B1 Needed for healthy nerves Whole wheat, peas, meat, beans, fish, peanuts 0.9 mg (1 mg = 1 x 10-3 g)
Vitamin B3 Needed for healthy skin and nerves Beets, liver, pork, turkey, fish, peanuts 12 mg
Vitamin B9 Needed to make red blood cells Liver, peas, dried beans, green leafy vegetables 300 μg
Vitamin B12 Needed for healthy nerves Meat, liver, milk, shellfish, eggs 1.8 μg
Vitamin C Needed for growth and repair of tissues Oranges, grapefruits, red peppers, broccoli 45 mg
Vitamin D Needed for healthy bones and teeth Milk, salmon, tuna, eggs 5 μg
Vitamin K Needed for blood to clot Spinach, Brussels sprouts, milk, eggs 60 μg
Some vitamins are produced in the body. For example, vitamin D is made in the skin when it is exposed to sunlight. Vitamins B12 and K are produced by bacteria that normally live inside the body. Most other vitamins must come from foods. Foods that are good sources of vitamins are listed in Table 1. They include whole grains, vegetables, fruits, and milk.
Not getting enough vitamins can cause health problems. For example, too little vitamin C causes a disease called scurvy. People with scurvy have bleeding gums, nosebleeds, and other symptoms. Getting too much of some vitamins can also cause health problems. The vitamins to watch out for are vitamins A, D, E, and K. These vitamins are stored by the body, so they can build up to high levels. Very high levels of these vitamins can even cause death, although this is very rare.
Minerals
Minerals are chemical elements that are needed for body processes. Minerals that you need in relatively large amounts are listed in Table (below). Minerals that you need in smaller amounts include iodine, iron, and zinc. Minerals have many important roles in the body. For example, calcium and phosphorus are needed for strong bones and teeth. Potassium and sodium are needed for muscles and nerves to work normally.
Minerals Needed For Good Health. Mineral One Reason You Need It Some Foods that Have It How Much of It You Need Each Day (at ages 9–13 years)
Calcium Needed for strong bones and teeth Milk, soy milk, green leafy vegetables 1,300 mg
Chloride Needed for proper balance of water and salts in body Table salt, most packaged foods 2.3 g
Magnesium Needed for strong bones Whole grains, green leafy vegetables, nuts 240 mg
Phosphorus Needed for strong bones and teeth Meat, poultry, whole grains 1,250 mg
Potassium Needed for muscles and nerves to work normally Meats, grains, bananas, orange juice 4.5 g
Sodium Needed for muscles and nerves to work normally Table salt, most packaged foods 1.5 g
Your body cannot produce any of the minerals that it needs. Instead, you must get minerals from the foods you eat. Good sources of minerals are listed in Table (below). They include milk, green leafy vegetables, and whole grains.
Not getting enough minerals can cause health problems. For example, too little calcium may cause osteoporosis. This is a disease in which bones become soft and break easily. Getting too much of some minerals can also cause health problems. Many people get too much sodium. Sodium is added to most packaged foods. People often add more sodium to their food by using table salt (sodium chloride). Too much sodium causes high blood pressure in some people.
Water
Did you know that water is also a nutrient? By weight, your cells are about two-thirds water, so you cannot live without it. In fact, you can survive for only a few days without water. You lose water in each breath you exhale. You also lose water in sweat and urine. If you do not take in enough water to replace the water that you lose, you may develop dehydration. Symptoms of dehydration include dry mouth, headaches, and feeling dizzy. Dehydration can be very serious. Severe dehydration can even cause death.
When you exercise, especially on a hot day, you lose more water in sweat than you usually do. You need to drink extra water before, during, and after exercise. The children in Figure below are drinking water while playing outside on a warm day. They need to drink water to avoid dehydration.
Figure 17.5
When you are active outside on a warm day, its important to drink plenty of water. You need to replace the water you lose in sweat.
Getting too much water can also be dangerous. Excessive water may cause a condition called hyponatremia. In this condition, water collects in the brain and causes it to swell. Hyponatremia can cause death. It requires emergency medical care.
Lesson Summary
The body needs food for energy, building materials, and substances that help control body processes.
Carbohydrates, proteins, and lipids provide energy and have other important roles in the body.
Vitamins and minerals do not provide energy but are needed in small amounts for the body to function properly.
The body must have water to survive.
Review Questions
What are three reasons that your body needs food?
Which nutrients can be used for energy?
Name two types of fiber and state the role of each type of fiber in the body.
What are some foods that are good sources of vitamin C?
What are two minerals that are needed for strong bones and teeth?
List some of the functions of proteins in the body. Based on your list, predict health problems people might have if they do not get enough proteins in foods.
Your body needs 20 different amino acids. Why do you need to get only ten of these amino acids from food? Name foods you can eat to get these ten amino acids.
Compare and contrast saturated and unsaturated lipids.
Identify three vitamins that are produced in the body. How are they produced?
Why do you need to drink extra water when you exercise on a hot day? What might happen if you did not drink extra water?
Further Reading / Supplemental Links
Alexandra Powe Allred. Nutrition. Perfection Learning, 2005.
Ann Douglas and Julie Douglas. Body Talk: The Straight Facts on Fitness, Nutrition, and Feeling Great about Yourself! Maple Tree Press, 2006.
DK Publishing. Food. DK Children, 2005.
Donna Shryer. Body Fuel: A Guide to Good Nutrition. Marshall Cavendish Children’s Books, 2007.
Linda Bickerstaff. Nutrition Sense. Rosen Central, 2008.
CK–12. High School Biology. Chapter 38, Lesson 1.
http://www.iom.edu/Object.File/Master/21/372/0.pdf
http://www.nlm.nih.gov/medlineplus/enc
y/article/002404.htm
http://www.textbookofbacteriology.net/normalflora.html
http://en.wikipedia.org/wiki/Vitamins
http://www.alexandrapoweallred.com/
Vocabulary
calories
Units used to measure the energy in food.
carbohydrates
Nutrients that include sugars, starches, and fiber; give your body energy; organic compound.
essential amino acids
Amino acids that must come from the proteins in foods; you cannot make these amino acids.
insoluble fiber
Large, complex carbohydrate; does not dissolve in water; moves through the large intestine and helps keep food waste moist so it can pass easily out of the body.
lipids
Nutrients such as fats that are rich in energy; organic compound.
minerals
Chemical elements that are needed for body processes.
nutrients
Chemicals in food that your body needs.
proteins
Nutrients made up of smaller molecules called amino acids; give your body energy; help control body processes; organic compound.
saturated fats
Found mainly in animal foods, such as meats, whole milk, and eggs; increase cholesterol levels in the blood.
soluble fiber
Large, complex carbohydrate; dissolves in water; helps keep sugar and fat at normal levels in the blood.
starch
Large, complex carbohydrate; found in foods such as vegetables and grains; broken down by the body into sugars that provide energy.
trans fat
Manufactured and added to certain foods to keep them fresher for longer. Foods that contain trans fats include cakes, cookies, fried foods, and margarine.
unsaturated lipids
Found mainly in plant foods, such as vegetable oil, olive oil, and nuts; also found in fish such as salmon.
vitamins
Substances that the body needs in small amounts to function properly.
Points to Consider
Think about how you can be sure you are getting enough nutrients?
Do you think knowing the nutrients in the foods you eat are important?
Do you have to keep track of all the nutrients you eat, or is there an easier way to choose foods that provide the nutrients you need?
Lesson 17.2: Choosing Healthy Foods
Lesson Objectives
State how to use MyPyramid to get the proper balance of nutrients.
Describe how to read food labels to choose foods wisely.
Explain how to balance food with exercise.
Check Your Understanding
What is a nutrient?
Why do you need extra energy when you exercise?
Introduction
Foods such as whole grain breads, fresh fruits, and fish provide nutrients you need for good health. However, various foods provide different nutrients. You also need different amounts of each nutrient. How can you choose the right mix of foods to get the proper balance of nutrients? Two tools can help you choose foods wisely: MyPyramid and food labels.
MyPyramid
MyPyramid is a diagram that shows how much you should eat each day of foods from six different food groups. It recommends the amount of nutrients you need based on your age, your sex, and your levels of activity. MyPyramid is shown in Figure below. The six food groups in MyPyramid are:
Grains—such as bread, rice, pasta, and cereal.
Vegetables—such as spinach, broccoli, carrots, and sweet potatoes.
Fruits—such as oranges, apples, bananas, and strawberries.
Oils—such as vegetable oil, canola oil, olive oil, and peanut oil.
Milk—such as milk, yogurt, cottage cheese, and other cheeses.
Meat and beans—such as chicken, fish, soybeans, and kidney beans.
Figure 17.6
MyPyramid can help you choose foods wisely for good health. Each colored band represents a different food group. The key shows which food group each color represents. Which colored band of MyPyramid is widest? Which food group does it represent?
Using MyPyramid
In MyPyramid, each food group is represented by a band of a different color. For example, grains are represented by an orange band, and vegetables are represented by a green band. The wider the band, the more foods you should choose from that food group each day. The orange band in MyPyramid is the widest band. This means that you should choose more foods from the grain group than from any other single food group. The green, blue, and red bands are also relatively wide. Therefore, you should choose plenty of foods from the vegetable, milk, and fruit groups, as well. You should choose the fewest foods from the food group with the narrowest band. Which band is narrowest? Which food group does it represent?
Healthy Eating Guidelines
Did you ever hear the saying, “variety is the spice of life”? Variety is also the basis of a healthy eating plan. When you choose foods based on MyPyramid, you should choose a variety of different foods. Follow these guidelines to make the wisest food choices for good health. Keep in mind that nutritional guidelines may change throughout life. As food provides energy and nutrients for growth and development, nutritional requirements may vary with body weight, age, sex, activity, and body functioning.
Make at least half your daily grain choices whole grains. Examples of whole grains are whole wheat bread, whole wheat pasta, and brown rice.
Choose a variety of different vegetables each day. Be sure to include both dark green vegetables, such as spinach and broccoli, and orange vegetables, such as carrots and sweet potatoes.
Choose a variety of different fruits each day. Select mainly fresh fruits rather than canned fruits and whole fruits instead of fruit juices.
When choosing oils, go for unsaturated oils, such as olive oil, canola oil, or vegetable oil.
Choose low-fat or fat-free milk and other dairy products. For example, select fat-free yogurt and low-fat cheese.
For meats, choose fish, chicken, and lean cuts of beef. Also, be sure to include beans, nuts, and seeds.
What about Ice Cream, Cookies, and Potato Chips?
Are you wondering where foods like ice cream, cookies, and potato chips fit into MyPyramid? The white tip of MyPyramid represents foods such as these. These are foods that should be eaten only in very small amounts and not very often. Such foods contain very few nutrients, and are called nutrient-poor. Instead, they are high in fats, sugars, and sodium, but low in other nutrients. Fats, sugars, and sodium are nutrients that you should limit in a healthy eating plan. Ice cream, cookies, and potato chips are also high in Calories. Eating too much of them may lead to unhealthy weight gain.
Food Labels
In the United States, packaged foods are required by law to have nutrition facts labels. A nutrition facts label shows the nutrients in a food. Packaged foods are also required to list their ingredients. An ingredient is a specific item that a food contains.
Using Nutrition Facts Labels
An example of a nutrition facts label is shown in Figure below. The information listed at the right of the label tells you what to look for. At the top of the label, look for the serving size. The serving size tells you how much of the food you should eat to get the nutrients listed on the label. A cup of food from the label in Figure below is a serving. The Calories in one serving are listed next. In this food, there are 250 Calories per serving.
Figure 17.7
Reading nutrition facts labels can help you choose healthy foods. Look at the nutrition facts label shown here. Do you think this food is a good choice for a healthy eating plan? Why or why not?
Next on the nutrition facts label, look for the percent daily values (% DV) of nutrients. A food is low in a nutrient if the percent daily value of the nutrient is 5% or less. The healthiest foods are low in nutrients such as fats and sodium. A food is high in a nutrient if the percent daily value of the nutrient is 20% or more
. The healthiest foods are high in nutrients such as fiber and proteins. Look at the percent daily values on the food label in Figure below. Which nutrients have values of 5% or less? These are the nutrients that are low in this food. They include fiber, vitamin A, vitamin C, and iron. Which nutrients have values of 20% or more? These are the nutrients that are high in this food. They include sodium, potassium, and calcium.
Using Ingredients Lists
The food label in Figure below includes the list of ingredients in a different food. The ingredients on food labels are always listed in descending order. This means that the main ingredient is listed first. The main ingredient is the ingredient that is present in the food in the greatest amount. As you go down the list, the ingredients are present in smaller and smaller amounts.
Figure 17.8
This food label includes the list of ingredients in the food. The main ingredient is enriched wheat flour, followed by high-fructose corn syrup. Why should you avoid foods with ingredients such as these at the top of the ingredients list?
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