1. Lesson Overview 30.2 Food and Nutrition

2. Lesson Overview Lesson Overview Food and Nutrition THINK ABOUT IT When you feel hungry, do you feel weak and just a little bit lazy? What do these sensations tell us about the purpose of food in the body?

3. Lesson Overview Lesson Overview Food and Nutrition Food and Energy Why do we need to eat? Molecules in food contain chemical energy that cells use to produce ATP. Food also supplies raw materials your body needs to build and repair tissues.

4. Lesson Overview Lesson Overview Food and Nutrition Nutrients Nutrients are substances in food that supply the energy and raw materials your body uses for growth, repair, and maintenance. The nutrients that the body needs include water, carbohydrates, fats, proteins, vitamins, and minerals.

5. Lesson Overview Lesson Overview Food and Nutrition Water The most important nutrient is water. Many of the body’s processes, including chemical reactions, take place in water. Water makes up the bulk of blood, extracellular fluid, and other bodily fluids. Water is lost from the body in sweat, urine, and with every breath that you exhale. Humans need to consume at least 1 liter of fluid each day to replace what is lost. If enough water is not taken in to replace what is lost, dehydration can result. This condition leads to problems with many body systems.

6. Lesson Overview Lesson Overview Food and Nutrition Carbohydrates Simple and complex carbohydrates are a major source of energy for the body. The starches found in grains, potatoes, and vegetables are complex carbohydrates, or polysaccharides. Starches are broken down by the digestive system into simple sugars.

7. Lesson Overview Lesson Overview Food and Nutrition Carbohydrates Whole-grain breads, bran, and many fruits and vegetables contain the complex carbohydrate cellulose, often called fiber. Although the human digestive system cannot break down cellulose, you need fiber in your diet.

8. Lesson Overview Lesson Overview Food and Nutrition Fats Fats, or lipids, are an important part of a healthy diet. Fats help the body absorb fat-soluble vitamins and are part of cell membranes, parts of nerve cells, and certain hormones. Deposits of fat protect body organs and insulate the body.

9. Lesson Overview Lesson Overview Food and Nutrition Proteins Proteins supply raw materials for growth and repair of structures such as skin and muscle. Many enzymes are made of proteins. Proteins also have regulatory and transport functions. Proteins can also be used as an energy source when other nutrients are in short supply.

10. Lesson Overview Lesson Overview Food and Nutrition Vitamins Organic molecules that the body needs in very small amounts are called vitamins. Most vitamins are needed by the body to help perform important chemical reactions. Most vitamins must be obtained from food. However, the bacteria that live in the large intestine can synthesize vitamin K and vitamin B 12.

11. Lesson Overview Lesson Overview Food and Nutrition Vitamins There are two types of vitamins: fat-soluble and water-soluble. The fat-soluble vitamins A, D, E, and K can be stored in the fatty tissues of the body. The body can build up small deposits of these vitamins for future use. The water-soluble vitamins, which include vitamin C and the B vitamins, dissolve in water and cannot be stored in the body. The tables on the following two slides list the food sources and functions of 14 essential vitamins.

12. Lesson Overview Lesson Overview Food and Nutrition 14 Essential Vitamins

13. Lesson Overview Lesson Overview Food and Nutrition 14 Essential Vitamins

14. Lesson Overview Lesson Overview Food and Nutrition Minerals Inorganic nutrients that the body needs, usually in small amounts, are called minerals. A constant supply of minerals in the diet is needed to replace those lost in sweat, urine, and digestive wastes.

15. Lesson Overview Lesson Overview Food and Nutrition Minerals—Sources and Functions

16. Lesson Overview Lesson Overview Food and Nutrition Nutrition and a Balanced Diet The science of nutrition—the study of food and its effects on the body—tries to determine how food helps the body meet all of its various needs. Nutritionists help people plan healthful, balanced diets that allow them to take in the right amount of energy, while obtaining nutrients in adequate amounts.

17. Lesson Overview Lesson Overview Food and Nutrition Balancing Your Diet Food labels can be used to plan a healthful diet and determine if you are consuming enough of some of the important vitamins and minerals.

18. Lesson Overview Lesson Overview Food and Nutrition Balancing Your Diet Note on the food label shown that fat contains about 9 Calories per gram, while carbohydrate and protein contain 4 Calories per gram.

19. Lesson Overview Lesson Overview Food and Nutrition Balancing Your Diet When using food labels, it is important to remember that Percent Daily Values are based on a 2000-Calorie diet. However, nutrient needs are affected by age, gender, and lifestyle. People who are more active than average have greater energy needs. When a person stops growing or becomes less active, energy needs decrease.

20. Lesson Overview Lesson Overview Food and Nutrition Maintaining a Healthful Weight Exercising about 30 minutes a day and eating a balanced diet can help maintain a healthful weight. Regular physical activity helps to maintain a healthful weight by burning excess calories. Other benefits of physical activity include strengthening of the heart, bones, and muscles.

21. Lesson Overview Lesson Overview Food and Nutrition Maintaining a Healthful Weight The American Heart Association recommends a diet with a maximum of 30 percent of Calories from fat, of which only 7 percent should be from saturated fats and 1 percent from trans fats. A diet high in these fats increases the risk for developing heart disease, Type II diabetes, or both.