Dr. Pierce's Tip of the Week - Archive

The Effects of Fiber on the Glycemic Index
January 30, 2004

The effects of fiber on the glycemic index of a food depend on the type of fiber ingested. Finely ground cereal fiber, such as in whole wheat bread has no effect whatsoever on the rate of starch digestion and subsequent blood sugar response. Similarly, any cereal product made with whole-wheat flour will have a glycemic index similar to that of its white counterpart. Breakfast cereals made with whole-wheat flours will also tend to have a high glycemic index values unless there are other influencing factors.

Only when the fiber is still intact, it can act as a physical barrier to digestion and then the glycemic index will tend to be lower. This is one of the reasons why legumes have exceptionally low glycemic index values (30-40). It is also one of the reasons why whole (intact) grains usually have low glycemic index values.

Viscous fiber thickens the viscosity or thickness of the mixture in the digestive tract. This slows the passage of food and restricts the movement of enzymes, thereby slowing digestion. The end result is a lower blood sugar response. Legumes contain high levels of viscous fiber, as do oats and pysllium (a seed which is a major ingredient in some breakfast cereals and laxatives). These foods all have low glycemic index values.

For the dieter this situation offers the following benefits:

1. You'll be satiated for a longer period of time after a meal, thus potentially staving off the hunger pains that you'll undoubtedly feel when dieting.

2. This will prevent the rapid introduction of nutrients into the blood stream and large spikes in blood glucose, fatty acids, and insulin. This will thus control both nutrient delivery and the hormonal response to meals. This will also help preven fat gain by controlling insulin.

3. This will prevent absorption of excess lipids and cholesterol, thereby decreasing the amount of utilizable calories in your good.

Providing fiber in the diet is one of the most effective methods to deal with insulin resistance. In the next Biosignature seminar, March 20-21 in Phoenix there will be a three hour segment on how to deal insulin resistance which affects 68 to 75% of the American.

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