Glycemic Index Help

How do I calculate the glycemix index of a food?

I am a borderline diabetic and my doctor has given me a list of foods I can eat and also which to stay away from. Basically, I have to eat foods that do not have a high glycemic index - but there are some foods that don't fall into either category on my list and I was wondering how to calculate what is ok and what isn't - obviously high sugar foods are no no's. But there are some foods that are more difficult to determine and I don't want to be calling my doctor every single time I have a question - that can get very expensive as well as tiresome. For instance, I cannot eat white bread or even whole wheat , but there are some low carbohydrate breads that are high in fiber - are these ok? Can someone please tell me if there is a specific formula to calculate the glycemic index of a food? Thank you.

Public Comments

1. The Glycemic index (also glycaemic index) or GI is a physiologically based measure of the effects of carbohydrates on blood glucose levels. Carbohydrates that break down rapidly during digestion releasing glucose rapidly into the bloodstream have a high GI; carbohydrates that break down slowly, releasing glucose gradually into the bloodstream, have a low GI. For most people, foods with a low GI have significant health benefits. The concept was developed by Dr. David J. Jenkins and colleagues [1] in 1980–1981 at the University of Toronto in their research to find out which foods were best for people with diabetes. Since the 1980s, Professor Jennie Brand-Miller at the University of Sydney has researched the role of carbohydrates, the GI and human health and is one of the world’s leading authorities. Carbohydrates that break down rapidly during digestion have the highest glycemic indices. Carbohydrates that break down slowly, releasing glucose gradually into the blood stream, have a low glycemic index. A lower glycemic index suggests slower rates of digestion and absorption of the sugars and starches in the foods and may also indicate greater extraction from the liver and periphery of the products of carbohydrate digestion. A lower glycemic response is often thought to equate to a lower insulin demand, better long-term blood glucose control and a reduction in blood lipids. The insulin index may therefore also be useful as it provides a direct measure of the insulin response to a food. The glycemic index of a food is defined by the area under the two hour blood glucose response curve (AUC) following the ingestion of a fixed portion of carbohydrate (usually 50 g). The AUC of the test food is divided by the AUC of the standard (either glucose or white bread, giving two different definitions) and multiplied by 100. The average GI value is calculated from data collected in 10 human subjects. Both the standard and test food must contain an equal amount of available carbohydrate. The result gives a relative ranking for each tested food The current validated methods use glucose as the reference food, giving it a glycemic index value of 100 by definition. This has the advantages that it is universal and it results in maximum GI values of approximately 100. White bread can also be used as a reference food, giving a different set of GI values (if white bread = 100, then glucose ≈ 140). For people whose staple carbohydrate source is white bread, this has the advantage of conveying directly whether replacement of the dietary staple with a different food would result in faster or slower blood glucose response. The disadvantages with this system are that the reference food is not well-defined, and the GI scale is culture dependent. A low GI food will release glucose more slowly and steadily. A high GI food causes a more rapid rise in blood glucose levels and is suitable for energy recovery after endurance exercise or for a person with diabetes experiencing hypoglycemia. The glycemic effect of foods depends on a number of factors such as the type of starch (amylose vs. amylopectin), physical entrapment of the starch molecules within the food, fat and protein content of the food and organic acids or their salts in the meal — adding vinegar for example, will lower the GI. The presence of fat or soluble dietary fibre can slow the gastric emptying rate thus lowering the GI. Unrefined breads with higher amounts of fiber generally have a lower GI value than white breads. Many brown breads, however, are treated with enzymes to soften the crust, which makes the starch more accessible. This raises the GI, with some brown breads even having GI values over 100. While adding butter or oil will lower the GI of meal, the GI ranking does not change. That is, with or without additions, there is still a higher blood glucose curve after white bread than after a low GI bread such as pumpernickel. The glycemic index can only be applied to foods with a reasonable carbohydrate content, as the test relies on subjects consuming enough of the test food to yield about 50 g of available carbohydrate. Many fruits and vegetables (but not potatoes) contain very little carbohydrate per serving, or have very low GI values. This also applies to carrots, which were originally and incorrectly reported as having a high GI. I was also diagnosed prediabetic last year see more here http://www.reddiabetes.com
2. http://www.mendosa.com is the place to go for a complete explaination of the glycemic index. David Mendosa was the originator of this plan and did the original testing of the foods. He also now has the Glycemic Load of a lot of foods posted on here. I follow the phase 2 of the South Beach Living food plan! With a few changes here and there if they affected my glucose readings very adversly. Like I cannot have milk products, any rices, or grain products or soft sweet fruits. And my former favorite Pinto Beans is a severe no no for me! The nutritionist told me to have beans frequently!!! Well she and the doctor don't have to deal with my headache when my glucose goes way high like over 300 from eating a bowl of beans!! Just watch the starchy veggies, soft sweet fruits, and the cereals/breads/rices and stuff like that. Be sure to plan in a "cheat treat" once a week!! Like a half cup of real ice cream or something you really like. Just keep the serving small!! Or you will not be able to stay with the food plan. That is from an Endo I saw for a while!!
3. The best one on the internet is :http://www.mendosa.com/gilists.htm Its has GLYCIMIC INDEX AND LOAD>If you do too many carbs try this>Lime and lemon juice delay the digestion of starches as does vinegar. I've found that 2-3 tablespoons of lime or lemon juice reduces my post prandial BG response by 10-20 points. Rick Mendosa's site has a lot of material on acids in the diet. Take a look at http://www.mendosa.com/acidic_foods.htm . And> Use ¼ to ½ teaspoon of cinnamon per day. Add it to your coffee, oatmeal, smoothie, or wherever you find it palatable. If you already suffer from diabetes, be sure to stay on a regular schedule with your cinnamon usage so that your blood sugar levels don't yo-yo.Use the same amount at the same time every day so that you can get a sense of how cinnamon affects your own personal blood sugar readings. Use the powdered spice or a cinnamon stick. Cinnamon pills are also available, and can be found easily via an online search. MHCP is water soluble and is not found in cinnamon oil. Good luck.