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Food Studies 30 Unit Three The Science Of Nutrition Food Studies 30 1 Unit 3 Food Studies 30 2 Unit 3 Unit Three: The Science Of Nutrition The following concept web illustrates the major topics presented in this unit. Proteins Fats Water Carbohydrates Vitamins and Minerals Essential Nutrients The Science of Nutrition Food Studies 30 3 Unit 3 Unit Overview Unit Two introduced you to the concept of nutrients and Canada’s Food Guide To Healthy Eating. In that unit you learned how Canada’s Food Guide can help you to choose nutrients that promote good health. This concern for nutrients and how the body uses them is the basis for the study of nutrition. Unit Three will introduce you to the science of nutrition. The study of nutritional sciences is extensive. This unit cannot provide an in-depth study of the science; rather, it will discuss basic information about nutrients, their functions, and sources. You will also be referred to several reliable Internet sites for more explanations. Information in this Unit will build on Unit Two by discussing fats, cholesterol, and fibre in more detail. This Unit does not contain activities within the course content. Instead, your assignment will consist of fifty multiple choice questions. All questions are found at the end of this Unit in the assignment section. The following are suggested web-based resources to help you add information to the course material, and to help complete the multiple choice questions that are the assessment for this Unit. You may use other reliable print and on-line resources to supplement the information provided. Tip Sheets from the Dietitians of Canada (topics include Vitamins and Minerals for Athletes ; Eating Well for Vegetarian Athletes ; Vitamin D: What you need to know ; Do I Need A Vitamin Or Mineral Supplement? ; and Fuel to burn, energy to spare: new value in carbohydrates and fibre are just a few of the topics you can find at the website below. http://www.dietitians.ca/public/content/eat_well_live_well/english/faqs_tips_facts/fact_sheets/index.asp Saskatchewan Ministry of Health has several fact sheets on nutrition on their website at: http://www.health.gov.sk.ca/nutrition-exercise Check out Calcium for your Bones, Cholesterol and your Health, Healthy Foods for my School, and others that interest you. Beef Information Centre (http://www.beefinfo.org/default.aspx) has information on topics such as the following: Iron: http://www.beefinfo.org/Default.aspx?ID=13&ArticleID=92&SecID=3 Protein: http://www.beefinfo.org/Default.aspx?ID=13&ArticleID=111&SecID=3 B Vitamins: http://www.beefinfo.org/Default.aspx?ID=13&ArticleID=93&SecID=3 Heart and Stroke Foundation Health Check™ http://www.healthcheck.org/en/nutritionalinformation/nutritional-information.html Heart and Stroke Foundation http://www.heartandstroke.com/site/c.ikIQLcMWJtE/b.3483951/k.8CDD/Healthy_Eating.htm Nutrient Value of Some Common Foods http://www.hc-sc.gc.ca/fn-an/nutrition/fiche-nutridata/nutrient_value-valeurs_nutritives-eng.php R.O.V.E.R. Food Studies 30 4 Unit 3 Essential Nutrients In the science of nutrition, the nutrient forms the base. As a reminder, nutrients are the chemicals that allow our bodies to build and renew themselves. Nutrients are divided into six categories. You were introduced to the following six categories of nutrients in Unit Two. carbohydrates fats proteins water vitamins minerals These six nutrients are called essential nutrients. They must be provided by food because the body does not produce them in sufficient quantities or cannot make them at all. The body depends upon the six nutrients for different purposes and it requires different amounts of each depending on age, gender, and health. Throughout Unit Three you will learn about each of the essential nutrients in more detail. As you work through the information you will also notice that there is discussion about how some nutrients depend on one another for proper functioning. Three of the six essential nutrients provide calories or energy. They are carbohydrates, fats, and proteins. Most foods are a combination of these three nutrients. For this reason, they are sometimes referred to as macronutrients. One gram of pure fat supplies 9 calories One gram of pure carbohydrate supplies 4 calories One gram of pure protein supplies 4 calories Vitamins and minerals are essential nutrients that provide no calories. They must be provided through the diet because the body cannot manufacture them in quantities adequate to ensure good health. These essential nutrients are needed in smaller amounts than the other nutrients; therefore, they are often referred to as micronutrients. Food Studies 30 5 Unit 3 Are You Getting All The Nutrients You Need? Scientists have established how much of certain nutrients people need. In Canada, Canada’s Food Guide To Healthy Eating provides direction in selecting a nutritionally balanced diet. There are also some specific sources of information available to judge a person’s dietary needs, including the Recommended Nutrient Intakes (RNI), sometimes called Reference Daily Intake (RDI), and the Recommended Dietary Allowances (RDA). Each of the above can be found in scientifically based charts that are guidelines for the amounts of many nutrients needed daily. The RNIs or RDIs are Canadian, while the RDA is an American reference. Canadians are encouraged to follow the recommendations of the RNI/RDI. The Canadian system is currently undergoing change. The RNIs are being replaced by the Dietary Reference Intakes (DRI). In time, you can expect to see more reference to this alternate system. Either way, know that the charts provide specific recommendations for determining the required amount of each nutrient. Combining the recommendations of the RNI/RDIs or the new DRIs, and Canada’s Food Guide To Healthy Eating can help you to be sure your diet is nutritious. Food Studies 30 6 Unit 3 Carbohydrates Carbohydrates are the most common nutrient. All foods of plant origin contain carbohydrates. These include fruit, vegetables, breads, and cereals. Milk is the only food of animal origin that contains carbohydrates (CHO). More than 50% of the total calories you consume should come from carbohydrates – but choose wisely. The three types of carbohydrates are sugars, starch, and fibre. Simple carbohydrates are sometimes called simple sugars. Glucose is the most important simple sugar. Through the process of digestion, all food breaks down to this simple sugar. Glucose is used for energy and for repair of body tissues. Carbohydrates can also be classified as complex. These carbohydrates consist of three or more simple sugars. Complex carbohydrates are low in fat and rich in vitamins, minerals, starch, and proteins. Rich sources of complex carbohydrates include grains such as wheat, corn, and oats, and foods made from them. Many Canadians eat too much sugar or simple carbohydrates, and not enough starch and fibre (complex carbohydrates). Some people believe that carbohydrate foods are fattening. This is a myth. Any food eaten in excess of energy needs can contribute to weight gain. Focus on enjoying carbohydrate foods in moderation, watch what is added to these foods, and balance your intake with active living. Eating carbohydrates does not cause diabetes like some people believe. Diabetes is a complex disease with many different causes. Type 2 diabetes (non-insulin dependent) is, however, influenced by a lifestyle that is sedentary and lacks a healthy diet. Different racial and ethnic groups in developed countries are also at a higher risk for diabetes. People of Aboriginal descent are three to five times more likely than the general population to have or develop diabetes. People of LatinAmerican, African, Asian, and Hispanic descent living in North America also have a higher incidence of diabetes. One of the best ways to prevent Type 2 diabetes is to eat well, enjoy regular physical activity, and maintain a healthy weight. Food Studies 30 7 Unit 3 Fibre Complex carbohydrates have the added value of providing dietary fibre. Dietary fibres are the parts of food that are not broken down in the intestinal tract. Because the body cannot digest dietary fibre, it passes through the digestive tract almost unchanged. For this reason, no calories are derived from it. You may be wondering why you need dietary fibre. Dietary fibre has several important roles. It provides bulk to maintain good bowel health and regularity. It helps to lower blood cholesterol levels. It helps to regulate blood sugar levels. Fibre is classified as soluble or insoluble. Fibre Type Soluble Dietary Fibre Insoluble Dietary Fibre Description A soft fibre that forms gels which absorb water. It helps in controlling blood sugar and in lowering blood cholesterol. Once called roughage, this type of fibre holds water and helps to prevent and control bowel problems. Best Sources Oat products, pulses, and pectin-rich fruit (apples, strawberries, and citrus fruit) Wheat bran and wheat bran cereals, whole grain foods (whole wheat or rye bread, brown rice), fruit and vegetables (including skin) There is no official Canadian Recommended Daily Intake for fibre at this time. Adults should try to eat 20 to 35 grams of fibre throughout each day. Children older than two years should be given fibre equal to their age plus five grams per day. Food varies in the amount of fibre that it contains. The following chart outlines some low to high sources of dietary fibre in four different food groups. Fibre Content Of Foods There are many resources that can tell you the amount of fibre in certain foods. Check out your favourite foods. Are they high, medium or low sources of fibre? http://www.dialadietitian.org/nutritionsubcat.asp?id=31 Food Studies 30 8 Unit 3 Fats Fats are essential for good health. They are found in both animal and plant foods, although fruits and vegetables contain very little fat. In addition to being a major source of energy, fats are also a source of essential fatty acids. Essential fatty acids (EFA) cannot be made by the body but are needed for normal growth and metabolism. Fat is a natural part of some food or it can be added in meal preparation. For healthy eating you need to focus on specific types of fat. Different types of fat affect your health in different ways. Some types of fat raise your blood cholesterol level, which increases your risk of developing heart disease. Read about fats in some of the selected web-sites in Unit Three to learn more about the functions of fat, where fat is found, the different types of fat, and ways to control your fat intake. Proteins Proteins are found in both animal and plant foods. Proteins are necessary for manufacturing, maintaining, and repairing body tissues. As well, they help to regulate body processes such as the balance of water, acids and bases, and the movement of nutrients in and out of cells. Proteins contribute to the immune system by producing antibodies. Unit Four of this course will look at proteins in more depth. Food Studies 30 9 Unit 3 Water The human body is approximately 70% water. The percentage of water in the body depends on the amount of body fat a person has. People with high percentages of body fat have lower percentages of body water than normal. Much of this water is found inside your cells. The remaining water is found in the spaces surrounding cells, and in your bloodstream. Water has many functions. Functions Of Water In The Body keeps your skin soft and elastic, and lubricates your joints helps chemical reactions occur carries nutrients and waste products throughout the body helps to regulate body temperature protects your body by acting as a shock absorber Although the principal sources of water are beverages, many foods contain large amounts of water. Some foods such as tomatoes, oranges, watermelon, and lettuce are over 80% water. You need to consume at least six to eight cups of water per day. This replaces the water lost in urine, sweat, and breathing. If you are very active or are in a hot climate, you will need to take in more water. Coffee, tea, soft drinks, alcohol, and other beverages that contain caffeine cannot help your need for water. These liquids are known as diuretics. Diuretics cause you to lose water. Food Studies 30 10 Unit 3 Vitamins And Minerals As you have learned, carbohydrates, fats, and proteins are the only nutrients that directly provide energy. However, they are not the only nutrients you need. Vitamins and minerals are just as important even though they do not provide calories. The body requires tiny amounts of vitamins and minerals. All the vitamins and minerals you need in a day combined weigh less than a dime. The amounts of vitamins and minerals you need may be small, but they are vital dietary substances. They are used in many of the body’s chemical reactions. Both help keep body processes working normally and are needed for growth and repair of the body. Minerals can also become part of body tissues. Vitamins Virtually all foods contain some vitamins. When vitamins were first discovered, they were given letter names (example: vitamin A, B, and so on). As scientists were able to analyze the chemical makeup of the vitamins, they gave vitamins chemical names such as riboflavin for vitamin B2. Today, many vitamins are still commonly referred to by their letter names. Types Of Vitamins Presently, there are thirteen vitamins. You will become familiar with these as you read information from the suggested web-sites and your own choices of reliable nutrition information. You should also be aware of two other types. The human body is capable of converting some substances into vitamins. These vitamins are known as provitamins. Beta-carotene is an example. It is used by the body to make vitamin A. Antioxidants are substances that keep oxygen-free molecules in the blood from combining with “bad” cholesterol. The antioxidant vitamins are C, E, and betacarotene. Food Studies 30 11 Unit 3 Meeting Your Vitamin Needs It is best to obtain the needed vitamins from foods rather than from supplements. Some vitamins can be found in a wide range of foods, while others are limited to just a few. Many factors contribute to a particular food’s vitamin concentration. an animal’s feed the manner by which the produce is harvested, stored, or processed the type of soil, sunlight, rainfall, and temperature in the food’s growing atmosphere You can control vitamin concentration through careful food preparation. The following are some hints for getting the vitamins you need. Be aware that different cooking methods influence the amount of vitamins retained. For instance, cooking in water causes vitamins to be washed out. This makes steaming, microwaving, roasting, and grilling better alternatives to boiling, stewing, and braising. Storage affects vitamin concentrations. For instance, prolonged exposure to air may destroy vitamin C, and riboflavin is sensitive to sunlight. For this reason, milk products are stored in opaque containers. Continue to read information on vitamins. Make notes of the different vitamins and their purposes and the sources of those vitamins. Use the chart that follows for your notes. This will help you answer the multiple-choice questions as the end of the lesson. Food Studies 30 12 Unit 3 Main Points To Remember Name Of Vitamin Vitamin Rich Food Deficiency (letter and/or chemical) Functions Sources Diseases Food Studies 30 13 Unit 3 Minerals Unlike vitamins that are produced and found in living materials, minerals are not produced and cannot be manufactured by the human body. They need to be obtained by eating plants that have drawn minerals from the ground or the flesh of animals that have eaten such plants. Most minerals become a part of the body, such as teeth and bones. Others are used to make substances that the body needs. Meeting Your Mineral Needs The amount of minerals you need to consume each day measures out to about 15 ml or a tablespoon. You need greater amounts of minerals than vitamins. Even though some minerals are needed in very tiny amounts, getting the right amount is important to health. Most minerals have a narrow safe range. You will see in the video you will watch that minerals are divided into different groups. You require varying amounts of each group. It is not difficult to get the right balance of minerals when you eat of wide variety of healthy foods. Certain groups of people may, however, need to be concerned about the amount of calcium, iron, and folacin they consume. A calcium calculator is provided on the Osteoporosis Canada website and is a quick and easy tool to measure your calcium intake for a day and to let you know how close you are to meeting your daily calcium needs. Give it a try. http://www.osteoporosis.ca/index.php/ci_id/5355/la_id/1.htm The several web-sites given and those print and on-line resources you find will help you learn more about the roles minerals play in our diets. Use the following chart to record information as you find it. Be sure to include calcium, iron, folacin, sodium and at least two other minerals in the chart. Pay particular attention to the function of the minerals, as well as quantities required, methods of preserving the minerals, and food sources. Food Studies 30 14 Unit 3 Main Points To Remember Name Of Mineral Food Studies 30 Mineral Rich Food Deficiency Functions Sources Diseases 15 Unit 3 How Vitamins And Minerals Work Together On their own, vitamins and minerals have specific functions. In addition, some nutrients depend on one another for proper functioning. The following list outlines some examples of how vitamins and minerals work together. Nutrient Combination Result Iron + vitamin C Increases iron absorption Calcium + vitamin D Increases calcium absorption Calcium + phosphorous Increases calcium absorption Copper + vitamin C or zinc Interferes with copper absorption Fortification And Enrichment Many foods in their raw form are packed with nutrients. However, some of these foods must be processed before consumers can use them. Grains and cereals are an example. Sometimes the entire kernel of grain is used. This creates a whole grain product. These products contain most of the kernel’s original nutrients. Removal of the kernel’s bran and germ, along with the fibre and nutrients they contain is common. The remaining endosperm is made into products such as white flour or breakfast cereals. The three main parts of the grain kernel are the bran, endosperm and germ. BRAN: outer covering consisting mainly of noncaloric cellulose fibre, B vitamins and protein ENDOSPERM: contains three quarters of the protein of the kernel and the B vitamins GERM: contains vegetable oil, vitamin E and some B vitamins Usually, some of the nutrients lost in processing are added to the product so the total is close to the original levels. The process is known as enrichment. In the case of grains and cereals, these foods are enriched with riboflavin, niacin, thiamin, and iron. Foods may also be fortified with vitamins or minerals. A fortified food is one in which nutrients not normally found in the food are added to make it more nutritious. Milk is an example. It is fortified with vitamin D to enhance calcium absorption. Food Studies 30 16 Unit 3 Unit Summary The concept web presented at the start of the unit will remind you about the important topics discussed in Unit Three. After you have completed the assignment, and you leave this unit, look back on some of the major topics that you have learned about. Think as well about how you could apply your learning in your daily life. Proteins Fats Water Carbohydrates Vitamins and Minerals Essential Nutrients The Science of Nutrition Food Studies 30 17 Unit 3 Food Studies 30 18 Unit 3