Week 3 - Carbohydrates
Week 3 - Carbohydrates Nutr 1020
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This 7 page Class Notes was uploaded by rgslc8 on Friday September 9, 2016. The Class Notes belongs to Nutr 1020 at University of Utah taught by Anandh Babu Pon Velayutham in Fall 2016. Since its upload, it has received 10 views. For similar materials see Scientific Foundations of Nutrition and Health in Nutrition at University of Utah.
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Date Created: 09/09/16
Carbohydrates Part 1 --- September 6 Important terms Functions of carbohydrates Energy o Carbs as the most important energy source o Red blood cells, central nervous system, and brain derive energy from glucose o Supplies calories: 4 Kcal/gram o 45-65% energy should be from carbohydrates Protein Sparing Effect o Enough carbs in diet prevent the breakdown of proteins for energy needs Intestinal Health o Fiber- important in intestinal health and waste elimination o Fiber (prebiotic) – stimulate the growth of good bacteria (probiotics) Protecting Against Disease o Reduces the risk of obesity, cv disease, and diabetes type 2 Classification of Carbohydrates C + H2O C H O Glucose C8 H12 O6 Simple Carbohydrates: o Monosaccharides (one sugar) Glucose, Galactose, Fructose (fruit sugar) o Disaccharides (two sugars) Sucrose (Glucose and Fructose), Lactose (Glucose and Galactose), Maltose (Glucose and Glucose) Complex Carbohydrate: o Polysaccharides (hundreds or thousands of sugars) Starch (amylose and amylopectin) Glycogen, stored in liver and muscles o Fiber Polysaccharides and non-carbohydrates Monosaccharides Glucose o Basic unit of all carbohydrate structure Fructose o Fruit sugar/ half of sucrose o In liver: fructose converted to glucose o Most of fructose in diet is from high fructose corn syrup o If consumed in too high amounts it will be converted to fat Galactose o Found bonded to glucose in milk sugar lactose o Mammary gland in lactating women: galactose resynthesized as glucose Disaccharides Milk Sugar: Lactose Table Sugar: Sucrose o Sugar cane, sugar beets, honey, maple syrup Maltose: formed from digestion of starch Polysaccharides Starch o 20% amylose and 80% amylopectin o Amylose – linear o Amylopectin – many branches, raises blood glucose rapidly: more places for enzymes to attack compared to the two ends of amylose Provides many sites for enzyme action Glycogen o Can be broken down very quickly: many branches o Liver glucose- contributes to blood glucose o Muscle glucose – supply glucose for muscle use Cellulose o Cannot be digested by humans Fiber Soluble fiber (pectins, mucilages, gums) o Metabolized by intestinal bacteria o Attract water and form a gel in GI tract, which slows digestion o Delays emptying of the stomach, keeping you feeling full which helps to control weight o Control blood glucose o Reduce absorption of cholesterol o Examples: Oats, lentils, apples, oranges, nuts, beans, carrots, flaxseeds Insoluble fiber (cellulose, ligins) o Not readily soluble in water nor easily metabolized by intestinal bacteria o Act as a natural laxative: speeds up the transmit of food through GI tract o Prevents constipation o Examples: Whole grains, vegetables, seeds Dietary Fiber vs. Functional Fiber Dietary Fiber Fiber that occurs naturally in plant foods o Example: lignin, cellulose, pectins, gums Functional Fiber Synthetic fibers that may be added to foods or used as a supplement o Example: chitin, psyllium “Total Fiber” = dietary and functional fiber combined How much fiber do we need? Women – 25 g per day (average: 17 g) Men – 38 g per day (average: 13 g) High fiber intake can pose some health risks: Reduced absorption of minerals o Fiber binds to essential minerals and keeps them from being absorbed Digestion of Carbohydrates Mouth: salivary amylase Small intestine: pancreatic amylase, sucrase, maltase, and lactase Large intestine: micro biotics Absorption of Carbohydrates Glucose and galactose: absorbed into absorptive cells (villi) through transport Fructose: absorbed through facilitated diffusion Carbohydrates in Food Whole grains, vegetables, fruits, dairy: all consist of carbohydrates Whole Grains Bran: outer layer that protects the seed o Fiber, B vitamins, minerals Endosperm: middle later o Carbs and proteins Germ: small nutrient rich core o Antioxidants, vitamin E, B vitamins, healthy fat, phytochemicals Processing: grinding, milling, separating o Refined grains: Endosperm Just some proteins and carbs Differentiating Whole Grains from Refined Grains Whole Grains o Good source of complex carbs, vitamins, minerals o Naturally low in fat o Reduces the risk of chronic diseases o 9/10 people don’t meet the whole grain recommendation o Sticker: whole grain vs 100% whole grain 100% stamp: 16 grams of whole grain per serving Whole grain stamp: 8 grams of whole grain per serving, may have added refined grains Vegetables Low in fat and calories Nutrients – potassium, folate, vitamin A and C Reduce the risk of several chronic diseases Recommended: 2.5 cups per day Fruits Recommended: 2 cups per day Dairy Stick to low fat dairy products o Recommended: 3 cups per day Carbohydrates 2 --- September 8 Important Terms Sweeteners – substances that impart sweetness to foods Nutritive Sweeteners – provide calories for the body Ex: sucrose Alternative Sweeteners – provide no calories for the body Ex: Splenda All monosaccharides and disaccharides are nutritive sweeteners High Fructose Corn Syrup (HFCS) Nutritive sweetener used in a lot of foods 55% fructose = “high” fructose Food manufactures prefer HFCS: low cost, better shelf-life, and broad range of processing applications Higher consumption is related to obesity because fructose is converted to fat in the body Average American consumes 60 pounds of HFCS per year ‘Added’ Sugars Caloric sweeteners added to foods during processing and preparation o Example: HFCS, sucrose High in calories and low in nutrients Daily limit: 9 teaspoons for men, 6 teaspoons for women o In reality we consume 20-30 per day o Added sugars = added risk o 17 teaspoons per 20 oz. bottle of Coke Sugar and Oral Health Sugar and other carbohydrates are turned into acids by oral bacteria o Acids dissolve the tooth enamel and underlying structures Leads to dental cavities/tooth decay Bacteria use the sugar to make plaque o Plaque adheres acid- producing bacteria to teeth and diminishes acid- neutralizing effect of saliva. Health Risks of Consuming too much Added Sugar Non-alcoholic fatty liver disease (liver failure) Weight gain and obesity Dental Decay Diabetes Heart Disease Alternative Sweeteners Synthetic sugar substitutes: derived from naturally occurring substances, including herbs or sugar itself. Intense sweeteners because they are many times sweetener than regular sugar (sucrose). Acceptable daily intake – safe Little or no calories Recommended Daily Allowance – Carbohydrates 130 grams o The amount of carbs required to provide the brain with an adequate supply of glucose) o 45 – 65% total calories should be from carbohydrates o Sources should be fruits, vegetables, whole grains, and beans In America, what are the top 5 carbohydrates? White bread Soda Cookies, cakes, donuts Sugars, syrups, jams Potatoes Protein Sparing Effect of Carbohydrates Carbohydrates for energy, protein for building and maintaining muscles and vital organs A diet that supplies enough digestible carbs to prevent breakdown of proteins for energy use. Low Carb Diets When carbs are less in diet, the body is forced to make glucose from body proteins. Not enough carbs in diet: o The metabolism of fat is insufficient Lactose Intolerance Lactase deficiency and lactose malabsorption may lead to a lactose intolerance o Abdominal pain, loose stools, bloating, flatulency Lactose is not being converted to glucose and galactose Management: o Reducing/eliminating the amount of dairy products o Using special products o Lactase enzyme preparations Regulation of Blood Glucose Normal blood glucose: 10-120 mg/100 ml of blood Hyperglycemia: high levels of glucose in the blood Hypoglycemia: low levels of glucose in the blood Immediately after a meal: o Blood glucose in elevated Pancreas releases insulin Glucose transported into cells (muscle, adipose tissue, and other cells) Liver: glucose is converted into glycogen o Normalization of blood glucose is achieved Fasting: o Blood glucose levels are low Pancreas releases glucagon Breakdown of glycogen to glucose Synthesis of glucose from fat and amino acids o Normalization of blood glucose is achieved Insulin-induced Glucose Transport Regulation of Blood Glucose by Stress Hormone o Stress increases the blood glucose level o Stress hormone: epinephrine o Glycogen is converted into glucose o Rapid flow of glucose into blood stream o Promotes quick mental and physical reactions Glycemic Index o Bodies react uniquely to different sources of carbs o The measurement of how a carb containing food raises blood glucose Example: baked beans vs. mashed potatoes Fiber will slow down the digestion process and help slow the rise of blood glucose and insulin Diabetes o Fasting blood glucose is more than 126 mg glucose/ 100 ml of blood o Type 1: the body is not producing enough insulin o Type 2: the cell is not binding to the insulin o Management: Diet, physical activity, medication