By: Rachel Neifeld, RD, CDN

When it comes to diabetes prevention, fiber is a key ingredient in keeping blood sugars within a healthy range. There are two types of fiber, insoluble and soluble, which should both be included in a healthy diet to reach the goal intake of 28 grams/day for women and 36 grams/day for men.

Research is finding, though, that soluble fiber, in particular, may be the type we should focus when it comes to preventing type 2 diabetes. Studies have shown that the soluble fibers barley or oat beta-glucans, guar, and psyllium have been shown to significantly decrease blood glucose and insulin response after eating. These soluble fibers are found in bars, beverages, bread, cereals, pasta, and crackers.  

This is good news for women at risk of developing gestational diabetes.  Risk factors include having a family history of type 2 diabetes, having had gestational diabetes in a previous pregnancy, and being overweight. Women can significantly reduce risk not only eating the total recommended amount of fiber each day, but also making sure to include the soluble form in each meal. Ongoing research supports that this may improve glucose metabolism and enhance insulin sensitivity. 

Soluble fiber is found in barley, oats, legumes, and root vegetables. This type of fiber absorbs water making the contents of the stomach more gelatinous and viscous. This binding nature causes nutrients from foods, including sugars, to be absorbed more slowly into the bloodstream, thereby reducing rapid spikes in blood sugar after eating.

Another mechanism by which soluble fiber may help control blood sugars is through the fermentation of soluble fibers in the colon which produces fatty acids which may have favorable effects of glucose metabolism.

Some great sources of soluble fiber and how much each contains per serving are listed below.

  • ½ cup Black beans: 2.4 grams
  • ¾ cup cooked oat bran: 2.2 grams
  • ½ cup red kidney beans: 2.0 grams
  • ½ cup Brussel Sprouts: 2.0 grams
  • ½ cup Sweet Potato: 1.8 grams
  • ½ small Mango: 1.7 grams
  • ½ cup cooked barley: 0.8 grams

Source: Effects of Soluble Fibers on Glucose Metabolism and Insulin Sensitivity in Individuals at Risk for Type 2 Diabetes; James W. Anderson, MD; Lore Kolberg, MS, FRD; and Joy Frestedt, Ph.D. RAC, CCTI.  Sports, Cardiovascular, and Wellness Nutrition, A Dietetic Practice Group of the Academy of Nutrition and Dietetics