WHY DO WE NEED FOOD? FOOD AND DIET

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1 WHY DO WE NEED FOOD? FOOD AND DIET Food gives us the energy required for chemical reaction to keep us alive Energy also required for many activities and to maintain body temperature Food also gives us nutrients the body needs to maintain health and life, to grow and develop The body needs a variety of nutrients - proteins, carbohydrates, fats, vitamins and minerals - and these come from the foods we eat. CLASSES OF FOOD MACRONUTRIENTS Macronutrients are nutrients that provide calories or energy. Nutrients are substances needed for growth, metabolism, and for other body functions. Since macro means large, macronutrients are nutrients needed in large amounts. There are three macronutrients

2 CARBOHYDRATES Carbohydrates are the most important source of energy (we need in the largest amounts). They contain the elements Carbon, Hydrogen and Oxygen Sources : starchy foods (like grain and potatoes), fruits, milk, and yogurt. Other foods like vegetables, beans, nuts, seeds and cottage cheese contain carbohydrates, but in lesser amounts. According to the Dietary Reference Intakes published by the USDA, 45% - 65% of calories should come from carbohydrate. Why do we need carbohydrates to survive? Carbohydrates are the body s main source of fuel. Carbohydrates are easily used by the body for energy. All of the tissues and cells in our body can use glucose for energy. Carbohydrates are needed for the central nervous system, the kidneys, the brain, the muscles (including the heart) to function properly. Carbohydrates can be stored in the muscles and liver and later used for energy. Carbohydrates are important in intestinal health and waste elimination. PROTEINS Fiber refers to certain types of carbohydrates that our body cannot digest. These carbohydrates pass through the intestinal tract intact and help to move waste out of the body. Diets that are low in fiber have been shown to cause problems such as constipation and hemorrhoids and to increase the risk for certain types of cancers such as colon cancer. Diets high in fiber; however, have been shown to decrease risks for heart disease, obesity, and they help lower cholesterol. Foods high in fiber include fruits, vegetables, and whole grain products. Proteins are required for growth and repair. Proteins can also be used as a source of energy. Proteins contain Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulphur. Proteins are very large molecules, so they cannot get directly into our blood; they must be turned into aminoacids by the digestive system. Protein is found in meats, poultry, fish, meat substitutes, cheese, milk, nuts, legumes, and in smaller quantities in starchy foods and vegetables. When we eat these types of foods our body breaks down the protein that they contain into amino acids (the building blocks of proteins).

3 Some amino acids are essential which means that we need to get them from our diet, and others are nonessential which means that our body can make them. Protein that comes from animal sources contains all of the essential amino acids that we need. Plant sources of protein, on the other hand, do not contain all of the essential amino acids WHY DO WE NEED PROTEIN TO SURVIVE? We need protein for: Growth (especially important for children, teens, and pregnant women) Tissue repair Immune function Making essential hormones and enzymes Energy when carbohydrate is not available Preserving lean muscle mass FATS Like carbohydrates, fats contain the elements Carbon, Hydrogen and Oxygen. Fat is found in meat, poultry, nuts, milk products, butters and margarines, oils, lard, fish, grain products and salad dressings. There are three main types of fat, saturated fat, unsaturated fat, and trans fat. Saturated fat (found in foods like meat, butter, lard, and cream) and trans fat (found in baked goods, snack foods, fried foods, and margarines) have been shown to increase your risk for heart disease. Replacing saturated and trans fat in your diet with unsaturated fat (found in foods like olive oil, avocados, nuts, and canola oil) has been shown decrease the risk of developing heart disease. WHY DO WE NEED FAT TO SURVIVE? Although fats have received a bad reputation for causing weight gain, some fat is essential for survival. We need this amount of fat for: Normal growth and development Energy (fat is the most concentrated source of energy) Absorbing certain vitamins ( like vitamins A, D, E, K, and carotenoids) Providing cushioning for the organs Maintaining cell membranes Providing taste, consistency, and stability to foods

4 VITAMINS & MINERALS Vitamins are chemicals which are required in very small quantities to keep you healthy. If a particular vitamin is missing from your diet you will suffer from a deficiency disease. Minerals are also needed in small quantities, but we need more of these than we need of vitamins. FIBRE AND WATER We do not // can not digest cellulose. This is a carbohydrate used by plants to make their cell walls. It is also called roughage. If you do not eat foods materials which contain fibre you might end up with problems of the colon and rectum. The muscles of you digestive system mix food with the digestive juices and push food along the intestines by peristalsis; if there is no fibre in your diet these movements cannot work properly. Our bodies also need water (6-8 glasses a day) To function properly, the body requires between one and seven liters of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors. With physical exertion and heat exposure, water loss will increase and daily fluid needs may increase as well. Water is excreted from the body in multiple forms; through urine and feces, through sweating, and by exhalation of water vapor in the breath. BALANCED DIET You must have carbohydrate, protein, fat, vitamins, minerals salts and fibre in the correct proportions. If there is not enough protein, you will not be able to grow properly and you will not be able to repair yourself i.e. wounds will not heal properly. If you do not have enough energy containing foods you will feel very tired, you will not have enough energy. If you have too much energy containing foods you will become overweight. If you think that you are overweight you might try taking more exercise to "burn off" some of the excess food which you ate at you last meal.

5 BALANCED DIET A balanced diet related to age, sex, and activity of an individual You must have carbohydrate, protein, fat, vitamins, minerals salts and fibre in the correct proportions. Energy can be obtained from carbohydrate, protein, and fat. Whatever mixture of carbohydrate, protein, and fat makes up the diet, the total energy must sufficient: 1. To keep our internal body process working (heart beating, breathing) 2. To keep up our body temperature 3. To meet the need of work and other activities The amount of energy that can be obtained from food is measured in calories or joule According to the Dietary Reference Intakes published by the USDA, 45% - 65% of calories should come from carbohydrate, 10% - 35% of calories come from protein, 20% - 35% of calories should come from fat.

6 GOOD FOOD VS. BAD FOOD GOOD FOOD GOOD FOOD VS. BAD FOOD BAD FOOD BAD FOOD GOOD FOOD Almost anything fresh is a good start. Better still is fresh organic food. Oily fish Vegetables, particularly orange- or dark green ones (carrots, chard, broccoli, squashes like pumpkins) Fruits Oats and other fibre-rich grains Pulses (beans, peas) Certain vegetable oils which are high in monounsaturates (olive, canola) Most processed foods which generally contain sugar, salt and fat Fatty foods like margarines, butter, cream, most cheeses, fatty meat Sugar and sugary foods like cakes and candies Food containing additives and colourings Sugary or diet soda drinks Salty foods Junk food Fast food and takeaways WHAT WILL HAPPEN IF U DON T EAT PROPERLY?

7 MALNUTRITION Malnutrition is a general term for a medical condition caused by an improper or insufficient diet. An extended period of malnutrition can result in starvation, disease, and infection. Malnutrition as the result of inappropriate dieting, overeating or the absence of a "balanced diet" is often observed in economically developed countries (eg. as indicated by increasing levels of obesity). Without enough protein we cannot grow properly or be able to repair our cells. Common forms of malnutrition include proteinenergy malnutrition (PEM) and micronutrient malnutrition. PEM refers to inadequate availability or absorption of energy and proteins in the body. Micronutrient malnutrition refers to inadequate availability of some essential nutrients such as vitamins and trace elements that are required by the body in small quantities. This problem is also seen in areas of the world suffering from famine - people can develop swollen abdomens from a disease called kwashiorkor famines have occurred because of drought, crop failure, pestilence, and man-made causes such as war or misguided economic policies. Bad harvests, overpopulation, and epidemic diseases THE CAUSES OF MALNUTRITION