Chapter 1: The Science of Nutrition 1.1 Nutrition Overview 1. What are the 6 classes of nutrients? Carbohydrates, lipids, proteins, vitamins, minerals and water are the 6 classes of nutrients. 2. What characteristics do the macronutrients share? They consist mainly of carbon, hydrogen and oxygen; provide energy; and are needed in large amounts. 3. How are vitamins categorized? The vitamins are divided into 2 groups – fat soluble (A,D,E and K) and water soluble (vitamin C, thiamin, riboflavin, niacin, vitamin B-6, pantothenic acid, biotin, folate and vitamin B-12). 4. How are minerals different from carbohydrates, lipids, protein, and vitamins? Minerals are structurally simple, inorganic substances. They do not contain carbon. 5. What are phytochemicals and zoochemicals? Phytochemicals are physiologically active compounds found in plants such as fruits, vegetables, legumes and whole grains. Saponins are an example of a phytochemical. Zoochemicals are physiologically active compounds found in animals. An example is conjugated linoleic acid. 1.2 Energy Sources and Uses 1. What does the term calorie mean? Calorie is the term used to express the amount of energy in foods. It is the amount of heat energy it takes to raise the temperature of 1 gram of water 1 degree Celsius (1C). 2. How do calories, kilocalories, and kilojoules differ? A calorie is a very small measure of heat, so food energy is expressed as kilocalories (kcal), the amount of heat energy it takes to raise the temperature of 1000 g of water 1C. However, the word calorie is commonly used to mean kilocalorie (kcal). The term kilojoule (kJ) is another way to express the energy content of food. It is a measure of work instead of heat. One kcal is equal to 4.18 kJ. 3. How many calories are in a food that has 8 g carbohydrate, 2 g alcohol, 4 g fat, and 2 g protein? This can be calculated as: Carbohydrate 8 grams X 4 kcal/g = 32 kcal Alcohol 2 grams X 7 kcal/g = 14 kcal Fat 4 grams X 9 kcal/g = 36 kcal Protein 2 grams X 4 kcal/g = 8 kcal Total 90 kcal 1.3 The North American Diet 1. What type of food provides most of the protein in the diets of North Americans? Animal foods such as meat, seafood, dairy products and eggs. 2. Which types of carbohydrates do most North Americans need to increase in their diets?