The glycemic index is a ranking of carbohydrate containing foods. Foods are ranked according to their immediate effect on blood sugar levels. The higher a food raises blood sugar, the higher its glycemic inde

Stubbs, Wendy

Williams, Pauline

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April 2004 FN/2004-01The Glycemic IndexPauline Williams, MPA, RD, USU Extension AgentWendy Stubbs, Dietetic InternWhat is the Glycemic Index?The glycemic index is a ranking of carbohydrate containing foods. Foods are ranked according to theirimmediate effect on blood sugar levels. The higher a food raises blood sugar, the higher its glycemic index.Scientists published the first index in 1981 when they were researching diet therapy for diabetes. This first listcontained 51 foods, and the list has continued to expand, with the most recent official list containing 750 foods.Fruits, grains, dairy products, some vegetables, pastas, and sugary desserts all contain carbohydrates, but have awide range of glycemic indices. Meats, fats and some vegetables have none or very small amounts ofcarbohydrates and thus the glycemic index of these foods is low or close to zero. Pure glucose is used as the standard to which other foods are compared, and is given the glycemic indexof 100. Most of today’s researchers use pure glucose as the standard mainly because it is the end product ofdigestion. However, white bread was the original reference food used when determining glycemic index levels.Glucose has a set index level of 100, which is considered the top of the scale. All other foods containing carbohydrates are ranked from 0 to 100 based on their effects on blood sugar compared to glucose. A few foods do have a higher glycemic index than glucose, with indexes over 100, such as jasmine rice, dates, and tofu based frozen desserts. Refined sugars and processed foods such as cookies, cakes, white breads, and crackers generally have high glycemic indexes. Whole grains and some fruits generally have lower glycemic indexes. Figure 1 shows an example of a person’s blood sugar response to a high versus a low glycemic index food. The graph shows how glucose, a high glycemic index food, raises blood sugar levels higher and faster than whole grains, a low glycemic index food.Influences on the Glycemic IndexDifferent factors that influence a food’s glycemic index include:Cooking Methods – the more cooking and processing a food goes through, the higher the glycemicindex. Physical Forms of Food – the more fibrous the food, such as whole grain seed, the slower it is digestedand the lower the glycemic index.Figure 1. Glycemic Index. The 2 hour blood sugarresponse of a high glycermic food (glucose) comparedto a low glycemic food (whole grains).Type of Starch – A food made of amylose starch has a lower glycemic effect than food composed ofamylopectin starch. Amylose starch breaks down slower than amylopectin. Amylose is found inlegumes such as kidney beans and lentils and some types of rice. Amylopectin is found invegetables such as potatoes and corn. Fiber – Soluble fibers slow digestion and effectively slow the availability of the starch to digestionwhich usually lowers a food’s glycemic index. Soluble fiber is found in oatmeal, dried beans,and some fruits and vegetables. Sugar – Foods contain various types of sugars. Fructose, found in fruits, is metabolized slowly, whichlowers the glycemic index of fruit. Which Foods Have a Low Glycemic Index?High glycemic index foods are those foods with an index greater than 70. Low glycemic index foodshave an index less than 55. One can’t tell the glycemic index of a food by its food group classification, but ingeneral low glycemic foods include: Grains – Oatmeal, pumpernickel bread, whole wheat bread, bran cereal, brown rice, most pastaFruits – apples, apple juice, apricots (dried), cherries, grapefruit, grapefruit juice, grapes, peaches,pears, pineapple juice, plums, oranges, and orange juice.Vegetables – yams, non-starchy vegetables such as broccoli, green beans, beets, and celery.Legumes – lentils, kidney beans, butter beans, split peas, chickpeas, lima beans, navy beans, pintobeans, baked beansDairy – milk, yogurt, low-fat ice creamTable 1 (following page) shows the glycemic index of some commonly eaten foods: Glycemic Index and Type 2 DiabetesLong-term studies have found that consumption of a high glycemic load diet is a predictor of type 2diabetes. Though diet is not the only predictor of the development of type 2 diabetes, adults who replace highglycemic foods in their diet with low glycemic foods can reduce their risk of diabetes.The major objective of diabetes control is to reduce high blood sugars. Constant high blood sugar indiabetes causes complications such as nerve damage, kidney disease, eye disease, and cardiovascular disease.Eating low glycemic foods may reduce frequent and rapid raises in blood sugar and as a result may decrease thepotential complications from diabetes. A low glycemic diet may also increase the body’s sensitivity to insulin.Changes in blood sugar caused from low glycemic foods are lower and more gradual, leaving more time forinsulin to respond to the raised blood sugar levels. Heart Disease and the Glycemic IndexA low glycemic diet may have a positive effect on those with heart disease. Eating low glycemic indexfoods is associated with decreased total cholesterol, decreased low density lipoproteins (LDL) or “badcholesterol,” and increased high-density lipoprotein cholesterol (HDL) or “good” cholesterol. Lower totalcholesterol levels, lower LDL cholesterol, and high HDL cholesterol levels are protective against heart disease.Obesity and the Glycemic IndexA diet combining low fat foods with low glycemic foods promotes better weight control than a low fatdiet alone. Low glycemic foods promote satiety and fat oxidation. Studies show that low-glycemic mealsdecrease hunger and subsequent eating. Eating low glycemic foods is appropriate in the treatment andprevention of obesity.Table 1. Glycemic Index of Commonly Eaten FoodsFood Glycemic Index Grams of Carbohydrates per servingBeans and LegumesKidney Beans, canned, ½ cupBaked Beans, ½ cupNavy Beans, ½ cupSplit Peas, boiled, ½ cup5248383219241921BreadsWhite, 1 oz sliceBagel, 1 each, 2 ozSourdough, 1.5 oz slice!00% Stone-ground Whole Wheat, 1.5 oz sliceRye Bread, 1 oz slice73725453501230201215Breakfast CerealsCorn Flakes™, 1 cup (1 oz)Total™, 3/4 cupCheerios™, 1 cup (.5 oz)Special K™, 1 cupMini Wheats™, 1 cupFrosted Flakes™, 3/4 cupAll-Bran Cereal™, ½ cup (.5 oz)8176746958554224272322212822Dairy FoodsVanilla Ice Cream, ½ cupSkim Milk, 1 cupNonfat Yogurt, artificial sweetener, 8 oz613224161217GrainsInstant Rice, 1 cupWhite Rice, 1 cupBrown Rice, 1 cupMacaroni, 1 cupSpaghetti, 1 cupFettuccine, 1 cup696455474240374237424257FruitsWatermelon, 1 cupCranberry Juice, 8 ozPineapple, fresh, 2 slicesBanana, 1 mediumOrange, 1 mediumApple, 1 mediumPear, 1 mediumGrapefruit, ½ medium726859524238382583110321018215PotatoesInstant mashed, ½ cupBaked white skinned, 1 mediumFrench Fries. 4.3 ozSweet Potato, ½ cupPotato Chips, 12 pieces85857561541430492015VegetablesParsnips, ½ cupCorn canned, ½ cupPeas frozen, ½ cupCarrots boiled, ½ cupYams, 3 oz9754484737151510324Choosing to Eat a Low Glycemic DietEating more low glycemic foods will benefit people at risk for heart disease, diabetes, and obesity.Many people will find it too time consuming to look up the glycemic index numbers on every food. In thefuture, glycemic indexes may be available as part of the nutrition information label. Until then here are somebasic guidelines to help you to choose a low glycemic diet: ! Reduce your consumption of refined and highly processed grain products like most prepared coldcereals and white bread. Choose whole grain breads, brown rice, and whole grain cereals such asoatmeal.! Eat non-starchy vegetables including leafy green vegetables. ! Eat plenty of fruits. Most have low glycemic indexes.! Choose foods that are high in fiber, they take longer to digest which usually helps lower the rate that thestarch is broken down.! Remember that combining foods and adding fat while cooking can change the glycemic index of foods –usually lowering the glycemic index.ReferencesBrand-Miller, J. C., Holt, S., Pawlak, D. B., & McMillan, J. (2002). Glycemic index and obesity. AmericanJournal of Clinical Nutrition, 76(suppl), 281S-285S. Brand-Miller, J., Burani, J., & Foster-Powell, K. (2000). The Glucose Revolution Life Plan. New York, NY:Marlowe and Company. Foster-Powell, K., Holt, S., & Brand-Miller, J. C. (2002). International table of glycemic index and glycemicload values: 2002. American Journal of Clinical Nutrition, 76, 5-56. Harvard Heart Letter. (2002, Dec.) Carbohydrates and health: not that simple… or that complex. Available athttp://www.health.harvard.edu/medline/Heart/H1202b/html. Accessed March 13, 2003.Harvard Women’s Health Watch. (2000, Dec.) Diet, glycemic index, and the food pyramid. Available athttp://www.health.harvard.edu/medline/Women/W1200a.html. Accessed March 13, 2003. Leeds A. (2002). Glycemic index and heart disease. American Journal of Clinical Nutrition, 76(suppl), 286S-289S. Willett, W., Manson, J., & Liu, S. (2002). Glycemic index, glycemic load, and risk of type 2 diabetes. AmericanJournal of Clinical Nutrition, 76(suppl), 274S-280S. Utah State University is committed to providing an environment free from harassment and other forms of illegaldiscrimination based on race, color, religion, sex, national origin, age (40 and older), disability, and veteran’s status. USU’s policy alsoprohibits discrimination on the basis of sexual orientation in employment and academic related practices and decisions.Utah State University employees and students cannot, because of race, color, religion, sex, national origin, age, disability, orveteran’s status, refuse to hire; discharge; promote; demote; terminate; discriminate in compensation; or discriminate regarding terms,privileges, or conditions of employment, against any person otherwise qualified. Employees and students also cannot discriminate inthe classroom, residence halls, or in on/off campus, USU-sponsored events and activities.This publication is issued in furtherance of Cooperative Extension work. Acts of May 8 and June 30, 1914, in cooperationwith the U.S. Department of Agriculture, Jack M. Payne, Vice President and Director, Cooperative Extension Service, Utah StateUniversity. 

The Glycemic Index

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