Do I Subtract Fiber from Carbohydrates?

Q: In the past, the American Diabetes Association (ADA) recommended that when a serving of food has 5 or more grams of fiber, people should subtract that number from the total grams of carbohydrates, because fiber is not broken down into glucose.

I don’t see this mentioned anymore, even in resources that incorporate high-fiber foods into diabetes diets. Now, more information discusses the glycemic index of high-fiber foods instead. Are people supposed to count and cover with insulin all of the carbohydrates in a serving of black beans, 23 grams, or subtract the 15 grams of fiber, and say it is 8 grams carbs?

Karen Lavine, RN, CDE
Albuquerque, New Mexico

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A: You are correct and the example is a good one. The ADA recommendations on adjusting carbohydrate calculation for high-fiber foods remain the same. Foods high in fiber are a healthy addition to a meal plan. Since fiber is not completely digested and absorbed, a high-fiber meal would not provide as much available carbohydrate as a low-fiber meal of similar total carbohydrate content.

A high-fiber food is one that contains 5 or more grams of dietary fiber per serving. When there are 5 or more grams of fiber per serving, subtract them from the total grams of carbohydrate to determine how much carbohydrate is available.

For example, a breakfast cereal containing 28 grams of total carbohydrate and 6 grams of dietary fiber can be counted as 22 grams [28 – 6 = 22] of available carbohydrate.

Anne Daly, MS, RD, CDE
Vice President, Health Care and Education
American Diabetes Association
Springfield, Illinois

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