There is so much conflicting information about what to eat and what not to eat that it can be very confusing to know what food to buy at the grocery store. You probably have a lot of time looking at nutrition facts labels trying to figure out what the healthiest option is. Carbohydrate-containing foods, such as bread, rice, pasta, breakfast cereals, crackers, granola bars, muffins, juices and desserts, wield the largest influence over your blood sugar concentrations. Keeping your blood sugar levels more stable can help you stay healthy. Carbohydrates comprise starches, sugars as well as fiber.
Sugar Content
When looking at a food label, you will always find the sugar content listed below the total carbohydrates. The sugar content refers not only to added sugar, but also to naturally-occurring sugar that may be present in a food, such as lactose from milk and yogurt and fructose from fruit. Added sugar can be listed under different names in the ingredients list. The sugary ingredients most often used include sucrose, glucose, fructose, high fructose corn syrup, dextrose, corn syrup, fruit juice concentrate, honey, maple syrup or agave syrup. The 2010 Dietary Guidelines for Americans recommends that no more than 25 percent of your daily calories come from added sugar.
Glycemic Index
The glycemic index, or GI, is a tool used to rank carbohydrates according to their ability to raise blood sugar levels. The GI of a food is not only influenced by the sugar content of a food, but also by factors such as the type of starch, physical entrapment, fiber viscosity, fat, protein, acid content, food processing and cooking. If a carbohydrate creates a large increase in blood sugar levels, this food has a high GI with a value of 70 of higher. On the other hand, if a carbohydrate leads to a smooth and steady rise in blood sugar concentrations, this food has a low GI, with a value of 55 or below. Foods based on low GI foods are associated with a healthy body weight, better athletic performance, lower risk of cardiovascular disease and improved diabetes control.
Glycemic Index of Sugars
Not all sugars impact blood sugar levels to the same extent. For example, table sugar has a GI value ranging between 58 and 65, while fructose has a GI between 11 and 23 and lactose has a GI of 43. Honey has a GI of varying degrees between 35 and 87, maple syrup has a GI of 54, and agave syrup has a GI between 10 and 19. This is why the listed sugar content of a food is not enough to determine the impact it can have on blood sugar levels and health.
Glycemic Load -- Integrating the Sugar Content and the Glycemic Index
The best way to predict the glycemic impact, or the impact on your blood sugar levels, of a carbohydrate-containing food is to estimate the glycemic load of a serving. The glycemic load, or GL, is a more complete concept introduced in 1997 by researchers at Harvard University to take into consideration both the GI of a food and its sugar and carbohydrate content. The higher the sugar content of the food you eat, the higher your blood sugars will go. Moreover, the higher the GI from the carbohydrates you include in your diet, the greater the rise in your blood sugar concentrations. Therefore, using both the sugar and carbohydrate content of a food in addition to its GI, which translates into the GL concept, is the best way to evaluate the quality and impact of the carbohydrates contained in a serving of food.
References
- Harvard Health Publications: Carbohydrates and Health: Not that Simple...or that Complex
- University of Sydney: The Glycemic Index
- "American Journal of Clinical Nutrition"; International Table of Glycemic Index and Glycemic Load Value; Kaye Foster-Powell et al; 2002
- FDA: How to Understand and Use the Nutrition Facts Label
- Dietary Guidelines for Americans 2010: Carbohydrates
