High-Fiber Cereal May Ward Off Diabetes

Eating a Fiber-Rich Breakfast Cereal May Lower Insulin Levels in Those at Risk

Medically Reviewed by Michael W. Smith, MD on June 18, 2004
From the WebMD Archives

June 18, 2004 -- Eating a bowlful of high-fiber cereal may help prevent type 2 diabetes and other health problems in people at risk for developing the disease.

A new study showed eating a high-fiber cereal lowered insulin production and reduced blood glucose levels in men with elevated insulin levels, a condition known as hyperinsulinemia.

People with hyperinsulinemia are in danger of developing type 2 diabetes because the cells in their bodies are resistant to the effects of insulin and cannot process glucose (sugar) properly. This causes the pancreas to produce more insulin in order to compensate. High insulin levels and insulin resistance have also been associated with an increased risk of heart disease.

By lowering the rise in insulin and sugar levels that normally follows eating a meal high in carbohydrates, researchers say people at risk for developing diabetes may be able to ward off the disease and its complications. Other research has shown that exercise and the diabetes medication Glucophage are also effective at preventing diabetes in these people.

High-Fiber Cereal May Help Lower Insulin Levels

In the study, which appears in the June issue of Diabetes Care, researchers compared the effects of eating a high- or low-fiber ready-to-eat breakfast cereal in 77 men without diabetes. Forty-two of the men had elevated insulin levels.

The men in the high-fiber cereal group ate 1.3 cups of cereal -- Fiber One from General Mills -- which provided nearly 36 grams of fiber. The low-fiber cereal group ate Country Corn Flakes from General Mills which had less than 1 gram of fiber in the 1-cup serving size.

The men with hyperinsulinemia were significantly heavier and had larger waistlines as well as lower HDL "good" cholesterol levels than the others. Being overweight is one of the biggest risk factors for diabetes, and HDL cholesterol is often low in people at risk for diabetes.

The study showed that blood sugar levels were significantly lower in all of the men after eating the high-fiber cereal than after eating the low-fiber cereal.

In addition, insulin production was significantly lower after eating the high-fiber cereal in the men with hyperinsulinemia than after eating the low-fiber cereal.

Previous research has shown that it takes a fairly large amount of fiber to reverse the metabolic abnormalities seen in diabetes. While the amount of fiber provided in the study can be obtained from any number of high-fiber cereals -- or other high-fiber foods -- this amount of fiber can be difficult to tolerate. This amount of fiber can lead to increased bowel movements and flatulence.

Researchers say the findings agree with previous studies showing that the effects of carbohydrate foods on blood sugar levels are the same in different people. But this study suggests that the effects of fiber- and carbohydrate-rich foods can have varying effects on insulin in different people.

"Longer-term studies are required before conclusions can be drawn as to whether a high-fiber breakfast cereal has any long-term benefits for the management of insulin resistance or obesity," write researcher Thomas M.S. Wolever, MD, PhD, of the University of Toronto, and colleagues.

The study was supported by General Mills and a grant from the Canadian Institutes of Health Research.