Nutrition-Chapter 4 – Flashcards

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Unrefined carbohydrates:
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Whole grains, legumes, vegetables, fruits, and milk, contain a variety of nutrients and phytochemicals with much of the fiber, vitamins, and minerals lost in the refining process
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Refined carbohydrates:
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White breads and baked goods
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Whole grains products:
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Contain all three of the major components of the grain kernel: the endosperm, bran, and germ
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Carbohydrates:
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Chemical compounds that contain carbon, hydrogen, and oxygen
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Simple carbohydrates:
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Include monosaccharides and disaccharides (two monosaccharides linked together) and are found in foods such as fruit, table sugar, honey, and milk.
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Complex carbohydrates:
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Referred to as dietary starch and are made of sugar molecules. Rich in fiber thus satisfying and health promoting. Generally not sweet to the taste like simple carbs.
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Monosaccharides
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Includes glucose, fructose, and galactose
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Disaccharides
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Maltose, sucrose (table sugar), lactose (milk sugar)
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Glucose:
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Glucose (aka blood sugar) is a monosaccharide that is the primary form of carbohydrate used to provide energy in the body.
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Fructose:
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Fructose (aka fruit sugar ) is A monosaccharide that is the primary form of carbohydrate found in fruit.
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Galactose:
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A monosaccharide that combines with glucose to form lactose.
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Maltose:
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A disaccharide composed of two glucose molecules that is formed in the intestines during starch digestion.
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Sucrose:
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aka table sugar - a disaccharide formed by linking fructose and glucose.
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Lactose:
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aka milk sugar - a disaccharide formed by linking a glucose molecule with a galactose, and is only found in animal products.
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Monosaccharide:
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The most basic unit of carbohydrates. These are the building blocs of disaccharides.
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Disaccharide:
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The carbohydrate formed when two monosaccharides undergo a condensation reaction which involves the elimination of a small molecule, such as water, from the functional groups only.
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Oligosaccharides:
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Short-term carbohydrates containing 3 to 10 sugar units and can be formed in the gut during the breakdown of polysaccharides.
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Glycogen:
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The storage form of glucose in animals and is a highly branched chain of glucose molecules that can be broken down quickly for energy.
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Starch:
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The storage form of carbohydrates in plants.
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Soluble fibers:
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Fibers that dissolve in water or absorb water to form viscous solutions and can be broken down by the intestinal microflora. Include pectin, gums and some hemicelluloses.
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Insoluble fibers:
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Fibers that do not dissolve in water and cannot be broken down by bacteria in the large intestine. Include cellulose, lignin, and some hemicelluloses.
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Lactose intolerance:
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A condition in which there is not enough lactase to digest lactose
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Glycemic response:
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How quickly or how high blood glucose rises after carbohydrate is consumed. Glycemic response can be quantified by using the glycemic load or glycemic index
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Supplying glucose to body cells:
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To ensure a steady supply of glucose to body cells, blood glucose levels are maintained within normal limits by the liver and the hormones insulin and glucagon. When blood glucose rises, insulin is released from the pancreas, allowing muscle and adipose tissue cells to take up the glucose. When blood glucose falls, glucagon is released to increase blood glucose by signaling glycogen to break down into glucose.
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Ketones:
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Molecules formed in the liver when there is not sufficient carbohydrate to completely metabolize the two-carbon units produced from fat breakdown.
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Diabetes mellitus:
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aka sugar diabetes - is a group of metabolic diseases in which there are high blood sugar levels over a prolonged period. Diabetes in General: describes a group of metabolic diseases in which the person has high blood glucose (blood sugar), either because insulin production is inadequate (type 2), or because the body's cells do not respond properly to insulin (type 1), or both
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Type 1 diabetes:
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Body NOT producing insulin because body attacks/destroys insulin (autoimune disorder)
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Type 2 diabetes:
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Body does not produce enough insulin or cells ignore insulin
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Gestational diabetes:
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Develops during pregnancy and causes high blood sugar and how your cells use sugar.
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Immediate symptoms of diabetes:
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Excessive thirst, frequent urination, blurred vision, and weight loss.
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Long-term complications of diabetes:
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Damage to the heart, blood vessels, kidneys, eyes, and nerves
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Medication for diabetes:
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Type1=insulin injected. Type 2=oral hypoglycemic agent (decreases glucose levels in the blood)
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Hypoglycemia:
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A condition in which blood sugar drops low enough to cause irritability, nervousness, sweating, shakiness, anxiety, rapid heartbeat, headache, and hunger.
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Cancer cells vs. normal cells:
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Cancer cells differ from normal cells b/c they divide without restraint and are able to grow in areas reserved for other cells.
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Fiber re colon cancer:
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Fiber may help reduce the risk of colon cancer by decreasing the amount of contact between the cells lining the colon and carcinogenic substances.
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RDA for carbohydrates:
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For adults and children is 130 g per day.
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Nonnutritive sweeteners:
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Alternative sweeteners that provide no caloriees and include saccharin, aspartame, sucralose, acesulfame K, and rebiana.
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Sugar alcohols:
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Sweeteners that are structurally related to sugars but provide less energy b/c they are not well absorbed.
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Why should we limit added sugars
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Added refined sugars provide energy, but few nutrients, thus lowering the nutrient density of our diet
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Carbohydrate Digestion and Absorbtion
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-In the mouth, the enzyme salivary amylase starts breaking starch into shorter ploysaccharides -In the stomach, salivary amylase is inactivated by acid so no carbohydrate digestion occurs -In the small intenstine, pancreatic amylase completes the job of breaking down starch into disaccharides and oligosaccharides -At the villi of the small intestine, enzymes attached to the microvilli complete the digestion of disaccharides and oligosacchardides into the three monosaccharides -In the large intestine, fiber and other indigestable, or resistant, carbohydrates are partially broken down by bacteria to form short-chain fatty acids and gas
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Why Lactonse Intolerance causes GI Distress
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Undigested lactose passes into the colon where it draws into water and is metabolized bacteria, producing gas and acids and causing abdominal distension, flatulence, cramping, and diarrhea
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How people with lactose intolerance can meet calcium needs?
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Those with lactose intolerance can still enjoy smaller amounts of dairy products as well as through the consumption of tofu, fish, vegetables, calcium-fortified products, and fermented dairy products
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Indigestible Carbohydrates
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-Fiber, some oligosaccharides, and resistant starch are not broken down by human digestive enzymes in the stomach and small intestine and therefore pass into the colon -Indigestible carbohydrates increase the volume of material in the lumen and thus add bulk or weight to the stool -When indigestable carbohydrates reach the colon, they serve as food source for the bacteria that reside and thus promote healthy microflora
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Why indigestible carbs increase intestinal gas
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Oligosaccharides, raffinose and stachyose are usually the culprits of the increase in intestinal gas after consuming beans
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How indigestible carbs affect nutrient absorbtion
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Fiber binds certain minerals such as zink, calcium, iron, and magnesium, preventing their absorbtion -Soluble fiber binds cholesterol and bile, thus reducing their absorbtion -In the stomach, fiber causes distention and slow sgastric emptying, thus increasing satiation
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Carbohydrates in the body
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Carbohydrate is an important source of energy for body cells
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Carbohydrate functions
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While the main function of glucose is to provide energy to the cells, each of the saccharides has other specific functions, such as cell communication, and to synthesize DNA and RNA
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Delivering Glucose to Body Cells
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After absorbtion, the monosaccharides travel to the liver via the hepatic portal vein -ONce in the liver, fructose and galactose are converted into glucose and used in one of three ways: for immediate energy, put into storage as glycogen, or converted into fatty acids for long term storage
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How Glucose Provides Energy
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- Glucose is metabolized through cellular respiration to generate ATP.
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Glycolysis
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- In the cytosol of the cell, glycolysis (anaerobic metabolism) splits glucose into two molecules of pyruvate. - Glycolysis produces high-energy electrons and two molecules of ATP per glucose. - Each pyruvate is either broken down to produce more ATP or used to make glucose via gluconeogenesis.
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Acetyl-CoA Formation
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- In the mitochondria in the presence of oxygen, one carbon is removed from pyruvate and released as carbon dioxide. - The remaining two-carbon compound combines with a coenzyme A (CoA) to form acetyl CoA, which enters the citric acid cycle.
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Citric Acid Cycle
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- Acetyl-CoA enters the citric acid cycle, where two carbons are lost as carbon dioxide, high-energy electrons are released, and a small amount of ATP is produced.
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Electron Transport Chain
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- Most ATP is produced in the final step of cellular respiration, the electron transport chain. - Here, the energy from the high-energy electrons released in the previous steps pumps hydrogen ions across the inner mitochondrial membrane. - As the hydrogen ions flow back, the energy is used to convert ADP to ATP, and the electrons are combined with oxygen and hydrogen to form water.
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What Happens When Carbohydrate is Limited?
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- When carbohydrate is limited, metabolism must shift to make sure that glucose is available to the brain and other cells that require glucose as an energy source.
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Why Protein Is Broken Down to Supply Blood Glucose
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- Since adequate dietary carbohydrate eliminates the need to use amino acids from protein to synthesize glucose through gluconeogenesis, carbohydrate is said to spare protein.
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Carbohydrates and Health
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A dietary pattern that is high in unrefined carbohydrates has been associated with a lower incidence of a variety of chronic diseases, whereas diets high in refined carbohydrates may contribute to chronic disease risk.
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Diabetes Mellitus
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- Diabetes Mellitus affects about 8.3% of the U.S. population.
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Why Diabetes Causes Symptoms and Complications
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- The symptoms and complications of diabetes result from the fact that, without sufficient insulin, glucose cannot be used normally.
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How diabetes is treated
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- The goal of diabetes treatment is to keep blood glucose levels within the normal range through diet, exercise, and medication.
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Diet
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- Individuals with diabetes can use exchange lists or a system of carbohydrate counting to estimate and control the amount of carbohydrate consumed with each meal.
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Exercise
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- Exercise increases the sensitivity of body cells to insulin so that glucose is available to fuel exercising muscles as well as promoting weight loss.
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Medication
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- In Type 1 diabetes, insulin must be injected while with those with Type 2 diabetes, oral hypoglycemic agents are taken.
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Hypoglycemia
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- Hypoglycemia is a condition in which blood sugar drops low enough to cause symptoms including irritability, nervousness, sweating, shakiness, anxiety, rapid heartbeat, headache, and hunger. - Hypoglycemia is a common complication of diabetes treatment.
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Dental Caries
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- The most well-documented health problem associated with a diet high in carbohydrates is dental caries, or tooth cavities. - Bacteria in the mouth can form colonies that stick to the teeth. - When carbohydrates - particularly simple carbohydrates - are consumed, they are metabolized by the bacteria, producing acids that dissolve the tooth enamel, forming dental caries.
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Carbohydrates and Weight Management
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- Carbohydrates contribute to weight gain when total energy intake exceeds needs
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Why Low-Carbohydrate Diets Promote Weight Loss
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- Low-carbohydrate diets lead to less food being consumed (carbohydrate is in many foods) - They also cause ketosis, which suppresses appetite, and therefore, food intake, leading to weight loss.
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Carbohydrates and Heart Disease
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- High-sugar diets can increase heart disease risk by raising blood lipid levels. - Unrefined carbohydrate sources help lower blood lipids and provide other dietary components that help protect against heart disease.
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Indigestible Carbohydrates and Bowel Health
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- Indigestible carbohydrates make the stool larger and softer, thus reducing the pressure needed to move material through the colon. - Indigestible carbohydrates, then, lower the risk of constipation, hemorrhoids, and the symptoms of diverticular disease.
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Indigestible Carbohydrates and Colon Cancer
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- Some people are more susceptible to cancer due to genetics, but the development of most cancers is believed to be influenced by environmental carcinogens, or cancer-causing agents.
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How Cancer Cells Differ from Normal Cells
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- Cancer cells differ from normal cells because they divide without restraint and are able to grow in areas reserved for other cells.
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Why Fiber May Protect against Colon Cancer
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- Cells in the colon may be exposed to carcinogens in the colon contents. - Fiber may help reduce the risk of colon cancer by decreasing the amount of contact between the cells lining the colon and these carcinogenic substances.
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Meeting Recommendations for Carbohydrate Intake
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A healthy diet is high in complex carbohydrates and simple carbohydrates from unrefined foods.
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Carbohydrate Recommendations
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- A small amount of carbohydrate is needed to fuel the brain.
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How Much Total Carbohydrate?
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- The RDA for carbohydrate for adults and children is 130 g per day. - Guidelines for healthy diets recommend 45 to 65% of energy from carbohydrates and a fiber intake of 25 g and 38 g, respectively for females and males.
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What Types of Carbohydrates Are Recommended?
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- Unrefined carbohydrates are good sources of fiber. - There is no RDA or Daily Value for added sugars, however, consumption needs to be limited to less than 10% of the energy coming from added sugars.
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Translating Recommendations into Healthy Diets
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- The typical North American diet includes about 50% of calories coming from carbohydrate with most coming from refined sources.
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The Role of Alternative Sweeteners
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- Alternative sweeteners can be used to reduce the amount of added sugar in the diet. - They do not contribute to tooth decay and can help keep blood sugar in the normal range. - They reduce the energy content of the diet if the calories they eliminate are not added back in other food choices.
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Types of Nonnutritive Sweeteners
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- Alternative sweeteners that provide no calories are often referred to as nonnutritive sweeteners and include saccharin, aspartame, sucralose, acesulfame K, and rebiana.
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Sugar Alcohols
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- Sugar alcohols are sweeteners that are structurally related to sugars, but provide less energy because they are not well absorbed.
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