Applied Nutrition Course for Nurses - Unit 2 - Carbohydrates PDF

Applied Nutrition course for nurses Unit two- Carbohydrates Nature of carbohydrates: Basic Fuels: Starches and Sugars Forms of carbohydrates: Two forms of carbohydrate occurring naturally in plant foods are: 1. Starches. 2. Sugars. Dietary Impor...

Applied Nutrition course for nurses Unit two- Carbohydrates Nature of carbohydrates: Basic Fuels: Starches and Sugars Forms of carbohydrates: Two forms of carbohydrate occurring naturally in plant foods are: 1. Starches. 2. Sugars. Dietary Importance of carbohydrates:  Carbohydrates comprise a major portion of the diets of people all over the world.  Rice is one of the world's most important sources of carbohydrate, feeding 3 billion people in the developing world,.  In the typical American diet about half of total kilocalories (calories) come from carbohydrates.  Carbohydrate foods are generally available, relatively low in cost, and easily stored.  Many carbohydrate foods can be kept in dry storage for fairly long periods without spoiling. Classification of carbohydrates: Carbohydrates contain the elements carbon, hydrogen, and oxygen with the hydrogen/oxygen ratio usually that of water—CH2O. Carbohydrates are classified according to the number of basic sugar or saccharine units. that make up their structure. 1. Simple carbohydrates: The monosaccharide's and di- saccharides are referred to as simple carbohydrates because of their relatively small size and structure. 2. Complex carbohydrates: The polysaccharide-rides, starches and certain forms of fiber, are called complex 11 | P a g e Applied Nutrition course for nurses carbohydrates based on their larger size and complicated structure. Monosaccharide's The simplest form of carbohydrate is the monosaccharide, or simple (single) sugar. The three monosaccharide's important in human nutrition are: o Glucose. o Fructose. o Galactose. Glucose 1. Glucose is a moderately sweet sugar found naturally in only a few foods, one being corn syrup. 2. Glucose is the common body fuel oxidized by cells to provide energy. 3. It is supplied to the body directly from the digestion of starch but also can be obtained from other simple sugars in food that are converted to glucose for immediate use or storage. 4. Glucose is the form in which carbohydrates circulate in the blood. Fasting plasma glucose levels normally range from 3-9 to less than 5.6 mol/L (70 to less than 100 mg/dl). 5. After a high-carbohydrate meal, plasma glucose levels will temporarily rise but should return to a level less than 7.8 remold/L (less than 140 mg/dl) within 2 hours. Fructose 1. Fructose, the sweetest of the simple sugars, is found in fruits and other natural substances such as honey. 2. Fructose intake has escalated since high-fructose corn syrup was introduced for use in food processing. 12 | P a g e Applied Nutrition course for nurses 3. High-fructose corn syrup is the sweetener in many soft drinks, fruit drinks, commercial baked products, and dessert mixes. 4. Honey is a natural sweetener but in fact contains no more vitamins or minerals than table sugar. 5. Honey should never be given to infants younger than 1 year of age because it may contain small amounts of the bacteria spores that produce botulism, a form of food poisoning that is often fatal. 6. Fructose is absorbed less efficiently than glucose, and amounts of 50 g or more can cause gastrointestinal distress in some individuals. Galactose 1. The simple sugar galactose is not found free in foods but is released through the digestion of lactose (milk sugar) and then converted to glucose in the liver. 2. This reaction is reversible, and in lactation glucose is reconverted to galactose for use in milk production. Disaccharides The disaccharides are double sugars made up of two monosaccharide's linked together. The three disaccharides of physiologic importance are sucrose, lactose, and maltose. Their monosaccharide components are as follows:  Sucrose = one glucose + one fructose.  Lactose = one glucose + one galactose.  Maltose = one glucose + one glucose. Sucrose 1. Sugar beets. ‫تنجز انسكز‬ 2. It is found in molasses and certain fruits and vegetables such as peaches ‫ خوخ‬and carrots. Sucrose is also an added sweetener in many processed foods. 13 | P a g e  Applied Nutrition course for nurses Lactose  Lactose is the sugar found in milk.  It is the least sweet of the disaccharides, only about one sixth as sweet as sucrose.  Although milk is relatively high in lactose, one of its main products—cheese—has little or none.  Up to 75% of adults worldwide are lactose intolerant, but many are able to digest lactose-free milk products such as cheese. Maltose 1. Maltose results from the breakdown of starch and is found in commercial malt products and germinating cereal grains. 2. Maltose occurs naturally in relatively few foods but is formed in the body as an intermediate product in starch digestion. Polysaccharides Complex carbohydrates are called polysaccharides because they are made up of many (poly) single glucose (saccharide) units. Food source of complex carbohydrates: 1. Hamburger bun 2. Whole wheat bread ‫خثش انقمح انكامم‬ 3. Corn flakes ‫رقائق انذرج‬ 4. Baked potato with skin‫انثطاطس انمشويح مع انجهد‬ 5. Beans ‫انفول‬ 6. Grain foods such as bread, cereal, rice, and pasta; legumes; and certain vegetables such as potatoes contain large amounts of starch. Whole grain breads and cereals, legumes, vegetables, and whole fruits supply fiber. Classification of complex carbohydrate: 1. Starch is the most important energy-yielding polysaccharide. 14 | P a g e Applied Nutrition course for nurses 2. Glycogen. 3. Dextrins. 4. Dietary fibers such as cellulose. Starch: 1. Starch is a complex carbohydrate made of many coiled and branching chains of single glucose units and yields only glucose on complete digestion. 2. Cooking not only improves the flavor of starch ‫ نكهح اننشا‬but also softens and ruptures the starch cells, making digestion easier. 3. Starch mixtures thicken when cooked because the substance encasing the starch granules has a gel-like quality that thickens mixtures in the same way as pectin causes jelly to set. Resistant Starch:  Now we know that some of the starch in particular foods such as cereals, potatoes, bananas, and legumes escapes digestion in the small intestine and enters the large intestine generally intact.  This starch, called resistant starch, can make up as much as 10% of the total starch in the typical Western diet.  Undigested starch into the colon has an important role in health.  Bacterial fermentation ‫ انتخمز انثكتيزي‬of resistant starch produces three short-chain fatty acids, acetic and butyric.  Butyric acid is the preferred energy source of the cells lining the colon, and when it is not available, the risk of colonic diseases such as ulcerative colitis ‫انتهاب انقونون‬ ‫ انتقزحي‬and colon cancer increases. 15 | P a g e Applied Nutrition course for nurses  Resistant starch has health benefits similar to those of dietary fiber. Glycogen:  The storage form of carbohydrate in animals is glycogen.  The storage form of carbohydrate in plants is starch.  Glycogen is synthesized in liver cells and stored in relatively small amounts in the liver and muscle.  Liver stores help sustain normal blood glucose levels during fasting periods such as sleep hours, and muscle glycogen provides immediate fuel for muscle action, especially during athletic activity. Dextrins 1. Dextrin are polysaccharide compounds formed as inter- mediate products in the breakdown of starch. 2. Starch breakdown is ongoing in the process of digestion. Glycemic Index:  Carbohydrates are broken down and enter the bloodstream at different rates.  These differences rise in blood glucose levels that occurs over 2 hours after eating a test food containing 50 g of carbohydrate with the response obtained from a reference food or carbohydrate, usually white bread or a glucose solution.  White bread is digested quickly, producing a rapid rise in blood glucose, and has been given the reference value of 100. Foods Glycemic Index: 1. Low glycemic index: less than 50. 2. Intermediate glycemic index: 55 to 70. 3. High glycemic index: greater than 70. 16 | P a g e Applied Nutrition course for nurses Examples of Foods Glycemic Index Food Glycemic index Baked potato (without skin) 121 Corn flakes 119 White bread 101 Soft drink 97 food cake 95 Cheese pizza 86 Spaghetti 83 Banana 76 Orange juice 74 ‫انثاسالء انخضزاء‬Green peas 68 ‫كم حثوب اننخانح‬All Bran 60 cereal Apple 52 ‫ كزيمح انحهية‬Skim milk 46 ‫ انفاصونيا‬Kidney beans 42 ‫ سكز انفاكهح‬Fructose 32 Functions of carbohydrate:  Provide energy: Provide energy to cells, especially brain cells that depend on glucose. An adult man has about 300 to 350 g of carbohydrate stored in his liver and muscle in the form of glycogen, and another 10 g of glucose is circulating in his blood. 17 | P a g e Applied Nutrition course for nurses  Glycogen reserves: Liver and muscle glycogen are in constant interchange with the body's overall energy system. These energy reserves protect cells, especially brain cells, from depressed metabolic function and injury and support urgent muscle responses as needed.  Protein-Sparing Action: Carbohydrates help to regulate protein metabolism.  Antiketogenic effect: carbohydrate influence the fat metabolism. The supply of dietary carbohydrate determine how much fat must be broken down to meet energy needs, thereby controlling the formation and disposal of ketones.  Energy sources of the central nervous system and the brain: The brain and central nervous system tissues have very low carbohydrate reserves—enough to last only 10 to 15 minutes—so they are especially dependent on a minute-to-minute supply of glucose from the blood. Fiber  Fiber is the non digestible material found in whole grain cereals, fruits, vegetables, and legumes. Because humans lack the necessary enzymes to break down these complex carbohydrates into forms that can be absorbed, they travel the length of the gastrointestinal tract and are eliminated in the feces. Their ability to promote regular bowel function has been recognized for generations. a) Dietary Fiber: Divided into soluble and insoluble fiber. Difference between soluble and Insoluble fiber 18 | P a g e  Applied Nutrition course for nurses Types of fiber Functions Sources  Holds water in the colon. Wheat bran, bran  increases fecal bulk in the cereals, whole grains, colon. popcorn, peanuts,  reduces intraluminal pressure apples, pears, berries, Insoluble fibers in the colon. bananas, peaches,  promotes growth of helpful legumes, peas, bacteria in the colon. cabbage family, corn, spinach, sweet potato, sunflower seeds 1. Binds cholesterol and bile Oat bran, oat cereal, acids; slows gastric emptying. barley, pumpernickel 2. provides fermentable materials bread, apples, citrus for colonic bacteria with fruits, pears, Soluble fibers production of volatile fatty broccoli, brussels acids and gas. sprouts, carrots, 3. Slows absorption of glucose, sweet potato, white preventing rapid rise in blood potato, peas, glucose levels. legumes. Health benefits of fibers 1. Increase in the fecal mass. The capacity of insoluble fiber to hold water and associated bacteria contributes to its bulk-forming and laxative effects. The added mass helps the food bolus move more rapidly through the small intestine, promoting normal bowel action. Dietary fiber prevents and alleviates constipation. 2. Binding of bile acids and cholesterol: Soluble fibers and lignin lower blood cholesterol levels through their ability to bind both 19 | P a g e  Applied Nutrition course for nurses cholesterol and bile acids. When cholesterol is bound to fiber, it cannot be absorbed and is carried through the intestinal tract and eliminated in the feces. 3. Effect on colonic micro flora: Dietary fiber along with resistant starch is fermented by bacteria living in the colon. This fermentation produces gas and short-chain fatty acids that nourish the cells lining the colon and stimulate their growth. The positive effect of fiber on the bifidobacteria population may prevent ulcerative colitis and help protect against colon cancer. 4. Positive effect on blood glucose and insulin levels: Foods rich in fiber have a low glycemic index and slow the rise in blood glucose following a meal. This blunting of blood glucose levels lowers the amount of insulin needed to move this glucose into muscle and fat cells, reducing the work of the beta cells of the pancreas. A diet high in fiber assists in both preventing and managing type 2 diabetes. 20 | P a g e