At the conclusion of this chapter students will be able to
Carbohydrates are one of the six major nutrients and the main source of energy. Examples of carbohydrates include sugars, starch, and fiber in the diet. The body’s top priority is to provide enough energy for all cellular activities needed to sustain life. Carbohydrates are the preferred source of energy. If the diet does not provide adequate carbohydrates the body will draw mainly upon proteins for its energy needs.
By eating adequate amounts of carbohydrates, proteins will be spared to be used for growth, development and regulatory functions of the body. If the diet is too low in carbohydrates, the body cannot break down fats completely, and incomplete fat break down products called ketones are produced and this may lead to Ketosis, a condition frequently encountered in diabetes mellitus, though in this case the cause is failure of the body to utilize carbohydrates rather that inadequate intake.
Fibers are carbohydrates which provide bulk in the diet. Fiber also helps to promote normal digestion and elimination of waste materials. Fibers also provide a feeling fullness by slowing the rate at which the stomach empties.
When the body does not make enough insulin or fails to use insulin correctly, glucose builds up in the bloodstream, a condition called diabetes mellitus. Another condition related to carbohydrate metabolism is called lactose intolerance. This condition is caused by a lack of the digestive enzyme lactase, which is needed to break down lactose. People who are lactose intolerant may experience gas, cramping, nausea and diarrhea when they consume dairy products.
Protein is an energy-yielding nutrient composed of carbon, hydrogen, oxygen, and nitrogen.
Proteins differs from carbohydrates and fats because of the presence of nitrogen. They are the building blocks of all protein molecules are amino acids. Protein is vital to the optimal growth and development of kids. Proteins account for 50% of the dry weight of the human body. Unlike lipids and carbohydrates, proteins are not stored, so they must be consumed daily. Current recommended daily intake for adults is 0.8 grams of protein per kg of body weight (more is needed for children).
The quality of a protein is determined by its ability to provide the 9 essential amino acids. Proteins from animal sources (eggs, dairy, meat, poultry, and fish) and one vegetable protein (soy) are all considered high-quality because they contain all of the essential amino acids in the necessary proportions. The function proteins includes,
If carbs and fats are lacking, the body uses protein as an energy source
Fats are made of carbon, hydrogen, and oxygen. Fats supply your body with energy, form your cells, maintain body temperature, and protect your nerves. A nutrient that provides energy and helps the body store and use vitamins is a fat. Unsaturated Fats have at least one unsaturated bond in a place where hydrogen can be added to the molecule. Unsaturated fats are usually liquid at room temperature (corn oil, soybean oil, peanut oil).
Unsaturated fats are classified as either monounsaturated fats or polyunsaturated fats. Fats that have all the hydrogen the carbon atoms can hold are called saturated fats. Saturated fats are usually solid at room temperature (butter, ghee, lard, margarine).
Too much saturated fat in your diet can lead to heart disease. Nutritionists recommend that 20-35% of your calories come from fat, primarily unsaturated fat.