Study Suggests High Dietary Fiber Related to Low Levels of Insulin Resistance in Women

Consumers can add insulin resistance as an increasingly important concern along with obesity and type 2 diabetes; however, food processors can add fiber and resistant starch in tasty, functional foods and beverages to help counter that concern.

By Mark Anthony, Ph.D., Technical Editor

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Many studies link fiber to body weight, digestive health and health in general. It's well known that different fibers have different effects. For example, soluble fibers tend to slow the movement of food through the small intestines, reducing the entrance of sugar into the blood. They also lower blood cholesterol by trapping and eliminating bile acids (made from cholesterol) that aid in fat digestion.

Insoluble fiber has a different effect: It reduces the transit time in the large intestine, and thus lowers the risk of diverticulosis. However, interest in fiber has expanded to include insulin resistance — the primary feature of type 2 diabetes.

Insulin resistance means that cells, particularly muscle cells (and, to a lesser degree, fat cells) resist the influence of insulin to take glucose out of the blood, leading to elevated blood sugar. The epidemic of obesity and type II diabetes is reflected in an epidemic of insulin resistance. One important strategy for reducing obesity and type 2 diabetes relies on understanding insulin resistance and the dietary factors that affect it — and for that, dietary fiber is considered to be an important consideration.

A recent study conducted at Louisiana State University looked at the dietary intake of Americans from 2003-2006. In this study, foods were ranked according to the percent of calories they provided to the American diet. The results demonstrated our lack of interest in dietary fiber. It's obvious Americans prefer yeasty sweets (breads and rolls, cakes, cookies) and many low- or no-fiber foods. Fruits, vegetables and whole grains were minor components, together comprising less than 5 percent of total daily calories. Obesity and type 2 diabetes incidence continues to rise, but not fiber intake.

The fact that dietary fiber is associated with decreased insulin resistance does not constitute a causal link. Still, increasing fiber intake is highly desirable for multiple health benefits

It's important to remember that association is not cause. The fact that dietary fiber is associated with decreased insulin resistance does not constitute a causal link. Still, increasing fiber intake is highly desirable for multiple health benefits, and one sure way to gain the benefit of both soluble and insoluble fibers is to increase the use of whole grains such as oats and barley, wheat and rye.

Another important source of fiber is not a true fiber at all but resistant starch, that portion of the starch molecule that resists digestion in the small intestines and functions like soluble fiber. It can even be labeled as fiber and counts as a fiber source. Resistant starch has been shown in multiple studies to help mitigate insulin resistance and offset symptoms of type 2 diabetes. Its high satiety effect further benefits the body by helping manage weight. Ingredion, Westchester, Ill., derives resistant starch from a high-amylose corn hybrid that can replace more energy-dense ingredients.

Many providers, including companies such as Grain Millers, Eden Prairie, Minn., and Viterra Inc., Regina, Saskatchewan, have increased the variety and format of grains and grain-derived products available to processors.

Fortification of common foods with fiber has been a successful strategy. "There is a wide variety of fibers available in the market, and the selection of a suitable fiber can be critical," says Vareemon Tuntivanich, R&D project leader in meat science for International Fiber Corp., North Tonawanda, N.Y.

"The processing step in which fibers are added to food products can also be important," she continues. "Often, fibers can be blended with other dried ingredients before use. In some special cases, fibers might need to be hydrated before use. Soluble fibers help to retain moisture or reduce water loss during cooking, thus providing improved texture. Taste panels have perceived these products to be less oily when compared to the control."

Tuntivanich notes that bakery products are still one of the most favorable candidates for fiber fortification. "Products such as breads and rolls, cakes, muffins, bars, cookies and cereals are the most common examples where fibers can be used for either functionality and/or fortification purposes," she says. "For instance, cellulose fibers can be used for shelf life improvement in breads and rolls, as well as for volume enhancement in cakes and muffins. In addition, certain fibers are commonly used in many gluten-free products to replace wheat-based ingredients."

As obesity and type 2 diabetes continue to be a global health crisis, we can add insulin resistance as an increasingly important concern. But processors can add fiber and resistant starch in tasty, functional foods and beverages to help counter that concern.

This article originally appeared in the March 2013 issue of Food Processing Magazine.

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