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Eating Well

If increasing your dietary fiber conjures up images of gnawing on pinecones or eating the breakfast cereal box along with the contents, you are not alone. It is true: Americans don’t eat enough dietary fiber. The average American only eats about half of the 20-35 grams recommended daily.¹ This is partially due to our love affair with processed foods and our seeming inability to eat 5 fruit and vegetables a day. To see how your diet rates, look up the fiber content of some of your favorite foods using the links at the end of this answer.

Soluble Fiber and Insoluble Fiber

• Soluble fibers form a gel when in contact with liquids. These are also the types of fiber associated with lowering cholesterol. Our diet should include 5-10 grams of soluble fiber as part of the total daily 20-35 grams.²
• Insoluble fiber, as the name implies, does not dissolve in the intestinal tract; it passes through. Insoluble fiber helps prevent constipation and a painful inflammation of the intestines, called diverticulitis. The 2009 Harvard School of Public Health Nutrition Source web site reported that while it is estimated that one third of Americans over age 45 are affected by diverticulitis, there was a 40% risk reduction of this condition with diets high in insoluble fiber.

How to Increase Fiber in Your Diet:

1. Eat 5 fruit and vegetables a day; eat the whole fruit or vegetables rather than drinking juice because the skins have most of the fiber.
2. Substitute whole grains for processed grains e.g., 100% whole wheat bread vs. white bread.
3. Eat legumes 2-3 times a week, e.g. chili, soup, on salads.
   

Natural Fiber vs. Functional Fiber:

• Natural fiber: Fruits, vegetables, whole grains, and legumes are the main sources of natural dietary fiber. These foods also contain other important nutrients such as vitamins, minerals, phytochemicals, and antioxidants.

• Functional fiber, or fiber that has been man-made or extracted from a food, doesn’t have the same nutritional benefits as dietary fiber.³ Examples of functional fiber include fiber supplements used to treat constipation and fiber added to processed foods. When taking fiber supplements, pay special attention to the manufacturer’s instruction on drinking plenty of water. Every little bit counts, but try to get most of your daily fiber intake from natural dietary fiber rather than from functional fiber.

Fiber’s Effect on Blood Glucose

You will notice that food labels list Fiber under Carbohydrates. Fiber is a type of carbohydrate that resists digestion and absorption by the human digestive system. This includes both dietary and functional fiber. Since fiber slows the digestion and absorption of carbohydrate, it can blunt the rise in your blood glucose. This means that your blood glucose can take longer to rise after meals, and also it may not rise as high.

Because of fiber’s effect on blood glucose, the fiber content in a meal may decrease the amount of insulin you require. For people who take short or rapid-acting insulin before meals, before calculating your insulin-to-carb ratio, the American Diabetes Association recommends: If the amount of fiber is greater than 5 grams per serving, then subtract half the grams of fiber from the total carbohydrate grams to determine the total adjusted carbohydrate grams.³

Checking your blood glucose before and after a high fiber meal will give you the best information on how fiber affects you. Be sure to check with your healthcare team for advice on customizing your doses.

Now that you have learned the benefits of fiber, you can better appreciate the phrase "an apple a day keeps the doctor away." I hope you will find ways to incorporate fiber into your daily meal plan.

References:

1. Position Statement of the American Dietetic Association: Health Implications of Dietary Fiber. J AM Diet Assoc. 2008;108:1716-1731.
2. Powers, Maggie. American Dietetic Association Guide to Eating Right When You Have Diabetes. John Wiley and Sons, Inc., Hoboken, New Jersey. 2003.
3. Diabetes Spectrum (2008); 21:283.