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Using the glycemic index to compare

Carbohydrates are often divided are measured at intervals over the into two categories—simple and following 2 hours to monitor the complex. Simple carbohydrates blood response. include mono- and disaccharides (i.e. fruit sugars and table sugars) Glossary and tend to be absorbed faster —a component of than complex carbohydrates or that has a high polysaccharides (i.e. breads, molecular weight and , ). However, due to branched structure and does the varying rates of digestion and not tend to gel in aqueous absorption between different glucose solutions carbohydrates, such simple time classifications may not always be —a component of the most useful. By comparing the area under the starch characterized by its graphed line with that obtained straight chains of glucose units What is the glycemic index? from consuming 50 grams of pure and by the tendency of its Foods are assigned glycemic glucose, a percentage is aqueous solutions to set to a index numbers based on the determined. For example, a stiff gel comparative increases in blood glycemic index of 60 indicates that glucose (sugar) levels they consuming 50 grams of that food disaccharide—two chain produce when eaten. A low to causes an increase in blood molecules of sugars moderate glycemic food causes a glucose 60 percent as great as that slow, gradual rise in blood sugar, produced by eating 50 grams of epidemiological studies— and maintains the increased pure glucose. medical science that deals with energy level for a longer duration. the incidence, distribution, A high glycemic food increases What factors influence the and control of disease in a the blood sugar concentrations glycemic index of foods? population quickly, thus providing energy to Many factors can influence the the body in a short period of glycemic index. Often foods with —the principal form in time. However, is released different glycemic indexes are which carbohydrates are stored in response to this rise in blood consumed simultaneously, which in the body sugar, which, in turn, brings the affects the glycemic index of the blood sugar down fairly rapidly. individual foods. In addition, glucose—sugar This rapid decrease reduces the other factors that can influence the energy supply and may trigger glycemic index include: glycemic index—measurement hunger. based on the amount of • Biochemical structure of the increase in blood glucose levels How is the glycemic index —for example, after eating a specific food determined? amylopectin is more readily Specific procedures can vary with absorbed than amylose the researcher. In general, human lipid—another term for fat subjects are fed 50 grams of • Intestinal absorption carbohydrate from a specific food. monosaccharide—single chain molecules of sugars The subjects’ blood glucose levels • Food particle size— smaller particles are absorbed faster polysaccharide—multiple chain molecules of sugars

N 3450 November 2003 • Mechanical and thermal Proponents and critics debate both period would show fewer processing—both break the the merits of the glycemic index differences between foods. food into smaller particles thus and how it is calculated. facilitating absorption * The type of dietary Clinical trials researching investigations on which the • Content and timing of the meals with different glycemic epidemiological studies base previous meal indexes confirm that eating their arguments are not low glycemic foods helps detailed enough to catch the • Accompanying foods that blood glucose levels stay more many variations in the include fat, fiber, or protein— level and thus reduces the glycemic indexes. The fat and protein decrease the amount of insulin released glycemic index can vary speed with which the stomach after a meal. When blood with varieties within a food empties, thus decreasing the glucose levels are fairly even group, method of rate of carbohydrate absorp- between meals, fat is also preparation, growing tion, which reduces the rate of metabolized at a healthier rate conditions, geographic elevating blood glucose and so blood lipid levels remain locations, genetic strain, produces a lower glycemic comparatively even. ripeness, acidity, fiber, index. protein, and fat content of Monitoring the glycemic index foods. Why is the glycemic index for various foods is one way important? diabetics can try to control * Many epidemiological People need the energy provided their blood glucose levels. studies show no effect of by food; they react to a lack of glycemic indexes. food by feeling hungry. Monitoring Studies where dietary habits energy levels is especially have been examined indicate The glycemic index does not important for athletes and people that foods with higher necessarily predict the insulin with health implications, such as glycemic indexes are a risk response, since it also is mellitus. Due to the factor for diabetes, , and affected by other factors in importance of balancing blood cardiovascular disease. Groups food, such as the kind of glucose levels in diabetics, low to consuming high glycemic protein and the protein moderate glycemic foods are foods were at greater risk of content. recommended to moderate blood developing chronic disease glucose in these individuals. than did the groups Current research is consuming foods with lower investigating whether rapid Athletes often choose foods that glycemic indexes. fluctuations in blood glucose optimize their glycogen stores. levels increase the risk of fat Most athletes benefit the most Critics have raised several gain and . from eating foods having a low to concerns regarding how the moderate glycemic index in their glycemic index is calculated. pre-game meal, and then eating * Differences in glycemic For more information on high glycemic foods immediately indexes are falsely elevated after exercise. However, the post- other nutrition topics when based only on a visit these Web sites: activity meal also should contain comparison of the Iowa State University low to moderate glycemic foods differences in blood glucose Extension nutrition— for optimal glycogen storage. elevation instead of on the www.extension.iastate.edu/ entire change in blood nutrition glucose levels. Iowa State University * The time used in many Extension publications— studies (2 hours) is too www.extension.iastate.edu/ short. Monitoring blood pubs glucose levels over a 4-hour Glycemic Indexes of Common Foods For additional glycemic Breads & Grains indexes visit these Web waffle - 76 baked beans - 40 sites: doughnut - 76 butter beans - 36 www.diabetesdigest.com/ bread, whole wheat – 73 split peas - 32 dd_nutrition2.htm bagel - 72 - 28 wheat bread, white - 70 kidney beans - 23 www.diabetesnet.com/ cornmeal - 68 soy beans - 15 diabetes_food_diet/ bran muffin - 60 glycemic_index.php , white - 56 Dairy rice, brown – 55 ice cream - 62 www.mesquitemagic.com/ wheat kernels - 48 yogurt, low fat sweetened - 33 glycemic_Index_chart.htm rice, instant (1 minute) - 46 milk, skim - 32 bulgur - 46 milk, full fat - 21 spaghetti, white - 41 spaghetti, whole wheat - 32 - 25 Snacks rice cakes - 82 Cereals jelly beans - 80 Rice Krispies® - 82 graham crackers - 74 Grape Nuts Flakes® - 80 life savers - 70 corn flakes - 77 angel food cake - 67 Prepared by Karin Westberg, Cheerios® - 74 wheat crackers - 67 graduate student; Ruth Litchfield, shredded wheat - 67 chips - 57 Ph.D., R.D., extension nutritionist; Grape Nuts® 67 popcorn - 55 and Diane Nelson, extension Life® - 66 oatmeal cookies - 54 communication specialist. All Bran® – 38 cake - 47 chocolate - 44 No endorsement of companies or Fruits corn chips - 42 their products is intended nor is watermelon - 72 - 13 criticism implied of similar pineapple - 66 companies or their products that are raisins - 64 Sugars not included. banana - 51 - 87 orange - 48 - 60 … and justice for all grapes - 43 - 43 The U.S. Department of Agriculture (USDA) prohibits discrimination in all its apple - 40 - 20 programs and activities on the basis of pear - 33 race, color, national origin, gender, religion, age, disability, political beliefs, Beverages sexual orientation, and marital or family Starchy soft drinks - 63 status. (Not all prohibited bases apply to carrots - 92 orange juice - 57 all programs.) Many materials can be made available in alternative formats for potatoes, instant - 88 apple juice – 41 ADA clients. To file a complaint of potatoes, baked - 78 discrimination, write USDA, Office of Civil Rights, Room 326-W, Whitten Building, potatoes, mashed - 73 14th and Independence Avenue, SW, sweet potatoes - 48 Washington, DC 20250-9410 or call 202- 720-5964.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914 in cooperation with the U.S. Department of Agriculture. Stanley R. Foods are listed from highest to lowest glycemic index within Johnson, director, Cooperative Extension category. Glycemic index was calculated using glucose as the Service, Iowa State University of Science reference with glycemic index of 100. (The University of Sidney, and Technology, Ames, Iowa. www.glycemicindex.com) File: FN 1