Fiber is a carbohydrate, but unlike sugars and starches, it’s not easily digested the body. As soluble fiber moves through your intestines, it mixes with water and forms a gel-like substance, which prevents macronutrient (read: carb) absorption. This slows down digestion which helps moderate how much sugar is going into the blood.
There are two types of fiber: insoluble and soluble. Insoluble fiber — found in wheat bran, vegetables, and whole grains — keeps your digestive tract running smoothly. Soluble fiber — found in oatmeal, nuts, seeds, beans, lentils, and peas — may help lower your cholesterol and improve blood glucose control. Learn more in Nutrition and Healthy Eating: Your GoodRx Guide.
Frances Largeman-Roth is a nutritionist and cookbook author in New York City.
Sandra Arévalo is a spokesperson for the American Association of Diabetes Educators and Academy of Nutrition and Dietetics and director of nutrition services and community outreach at South Bronx Health Center.
References
Joslin Diabetes Center. (n.d.). How does fiber affect glucose levels?
U.S. National Library of Medicine, MedlinePlus. (2022). Soluble fiber vs. insoluble fiber.
Weickert, M, et al. (2008). Metabolic Effects of dietary fiber consumption and prevention of diabetes. Department of Endocrinology, Diabetes, and Nutrition, Charité-University-Medicine-Berlin.
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