How Does Fiber Affect Blood Glucose Levels?
Fiber is a type of carbohydrate (just like sugars and starches) but since it is not broken down by the human body, it does not contribute any calories. Yet, on a food label, fiber is listed under total carbohydrate. So this gets kind of confusing for people who have diabetes. Carbohydrate is the one nutrient that has the biggest impact on blood glucose. So, does fiber have any effect on your blood glucose?
The answer is that fiber does not raise blood glucose levels. Because it is not broken down by the body, the fiber in an apple or a slice of whole grain bread has no effect on blood glucose levels because it isn't digested. The grams of fiber can actually be subtracted from the total grams of carb you are eating if you are using carbohydrate counting for meal planning.
So, fiber is a good thing for people with diabetes. Of course, most of the foods that contain fiber (fruits, vegetables, whole grain breads, cereals, and pastas) also contain other types of non-fiber carbohydrate (sugar, starch) that must be accounted for in your meal plan.
The average person should eat between 20-35 grams of fiber each day. Most Americans eat about half that amount. A study in the New England Journal of Medicine showed that people with diabetes who ate 50 grams of fiber a day — particularly soluble fiber — were able to control their blood glucose better than those who ate far less.
So if fiber does not give us any calories, why exactly should you eat it? There are two types of fiber: insoluble and soluble. Insoluble fiber keeps your digestive tract working well. Whole wheat bran is an example of this type of fiber. Soluble fiber can help lower your cholesterol level and improve blood glucose control if eaten in large amounts. Oatmeal is an example of this type of fiber.
Another benefit of fiber is that it adds bulk to help make you feel full. Given these benefits, fiber is important to include in the daily diet for people with diabetes, as well as those who don't have diabetes. You can add fiber by eating whole grain products, fruits, vegetables, and legumes. Leave the skin on fruits and vegetables, as it is high in fiber. Eat whole grain breads and crackers. And be sure to increase your fiber intake gradually, and remember to drink 6-8 glasses of water per day to avoid constipation.
Page last updated: February 16, 2019