The glycemic index can help in selecting healthier foods.
The glycemic index provides a measure of how quickly foods containing carbohydrate are broken down and assimilated into the blood as glucose. For diabetics and non-diabetics alike, the glycemic index can be utilized to help choose healthier carbohydrates for goals such as improved glucose control, reduced risk factors for chronic disease and for weight loss, according to an article published in "The American Journal of Clinical Nutrition" in 2002.
The Glycemic Index
The glycemic index provides a means of comparing the effects of carbohydrate-containing foods on blood sugar. Foods at the low end of the 100-point scale break down slowly, causing a slower rise in blood glucose, while foods closer to the top of the scale are broken down quickly, often precipitating a quick spike in blood glucose. According to the Harvard School of Public Health, the GI of a given food is influenced by a number of factors including the type of carbohydrate present as well as the fiber, fat and acid content of the food. Starch, a type of complex carbohydrate found in potatoes and bread is broken down quickly and adds to a higher GI value, whereas fructose, the sugar found in fruit is absorbed more slowly. Fiber, fat and acid content generally lower the GI of a food by slowing digestion and the release of glucose into the blood. The degree of processing of grains also influences the GI, as processing generally removes the fiber content of whole grains.
Low-GI Vegetables and Fruits
Low-GI foods have a value of less than 55. Vegetables in this category include carrots, sweet potatoes, parsnips and sweet corn. These are more starchy vegetables, yet they remain low-GI due to their fiber content. It is important to note that most non-starchy vegetables such as broccoli, green beans and leafy greens have so little carbohydrate content, they do not measure in GI testing. Most fruits, such as apples, apricots, bananas, oranges, grapefruit, peaches, pineapples, pears and berries, fit in the low-GI category.
Low-GI Grains, Nuts and Beans
Beans, lentils, nuts and seeds are included in the low-GI category, as most varieties measure below 55 on the glycemic index. Whole-grain products like brown and white rice, rolled and steel-cut oats, as well as bulgur wheat, are considered low-GI grains. Low-GI breads and cereals generally are less refined with more fiber, such as whole-wheat and whole-grain breads and cereals like bran flakes and other whole-grain varieties.
Other Common Foods
Other low-GI foods include dairy products like milk and yogurt, while the bulk of dairy products have too few carbohydrates to be tested on glycemic index. Beverages vary widely, with soft drinks, alcohol and fruit juices generally having a high GI, while vegetable juices, soy milk and almond milk are generally low-GI beverages, according to the Sydney University GI Research Service. Refined foods such as chips, sweets and other snack foods will vary considerably depending on the macronutrient makeup of the food. Meats have no carbohydrate content and cannot be tested for glycemic index.
The glycemic index can be a useful tool; however, it is still advised for diabetics to keep in mind overall portion sizes. Focus food choices on vegetables, fruits, legumes, whole-grain products and small portions of lean proteins, according to the American Diabetes Association. Even consuming too much of healthy, low-GI carbohydrates can cause increases in blood sugar. Always consult your physician before making any significant changes to your diet.