Eat more dietary fiber and whole grains are two of today’s key healthy eating messages. But confusion looms about how whole grains and dietary fiber differ as well as how much of each to eat. Read on for answers.

Same or Different?

You find dietary fiber in foods from several carbohydrate-containing groups: fruits; starchy vegetables, such as corn and peas; legumes, such as beans, peas, and lentils; and in nonstarchy vegetables, such as broccoli, green beans, and carrots. Foods that contain whole grains, such as breads and cereals, are just one source of dietary fiber.

Terms Defined:

Whole grains contain the entire grain seed of a plant and are rich in dietary fiber, vitamins, and minerals.

Dietary fiber: Fiber is a source of carbohydrate (remember: dietary fiber is listed on the nutrition facts under Total carbohydrate). Dietary fiber can not be digested by enzymes in the small intestine (site of digestion of most carbohydrates) and therefore it is doesn’t provide immediately available glucose.

The three categories of dietary fibers:

Insoluble fibers are non-digestible and therefore don’t raise blood glucose. They grab onto liquid as they travel down the gastrointestinal tract which in turn pushes food through the gastrointestinal tract. Hence, their role in producing bulkier and softer bowel movements, and preventing colon and rectal cancer.

Soluble fibers are fermented by bacteria in the large intestine and produce a small amount of glucose. The way that soluble fibers can lower blood glucose and cholesterol (minimally) is by binding onto them during digestion and increasing the amount you excrete.

Resistant starches resist digestion until they reach the large intestine. In the large intestine resistant starches cause bacteria to produce fatty acids. The fatty acids provide several health benefits, one of which is lowering glucose after eating. Foods that contain large amounts of resistant starch are: legumes; cooked and cooled potatoes, pasta and rice; and oatmeal.

How Much to Eat

Dietary Fiber: Americans, on average, consume about 10 to 13 grams a day, about half of the 20 to 35 grams a day recommended.

Whole Grains: Make half your servings of starches (at least 3, each providing ~16 grams of whole grains) from whole grains for a total of at least 48 grams a day.

Effect on Blood Glucose

Research shows that large amounts (> 50 grams per day) of dietary fiber (all types) can lower blood glucose (as well as improve total and  LDL-cholesterol). That’s good news, but most people’s intake falls far short (see How Much to Eat). Reality is that the average person’s intake of fiber doesn’t impact glucose or lipids much.

Research shows that whole grains are one component of a healthy eating plan that can help prevent type 2 diabetes.

Fiber and Your Carb Counts

Question: Should you subtract the dietary fiber from foods/meals from your total carb count? Answer: No or Yes.

The concern: Potential hypoglycemia if you don’t subtract some carbohydrate contributed by dietary fiber from your food/meal carb count. All things considered, it’s unlikely that a reasonable amount of fiber (<5 grams/meal) would increase the risk of hypoglycemia for most people with diabetes.

More specific No or Yes:

No, if you have type 2 diabetes and take no medication or take one or more blood glucose lowering medications, eat an average amount of fiber (<5 grams/meal) and don’t have the ability to adjust your medication dose on your own.

Yes, if you take meal-time insulin based on the amount of carbohydrate you eat, eat some foods/meals that are high in fiber (> 5 grams), are very accurate with your carb counts and are willing to do this math. Use this guideline from American Diabetes Association (published in Choose Your Foods: Exchange Lists for Diabetes, 2008) to compensate for the estimated amount of insoluble fiber in the food/meal that won’t raise your blood glucose: “if a food (or meal) contains more than 5 grams of fiber, subtract half the grams of fiber from the total carb grams to get a reduced total carb grams.” Base your meal-time insulin dose on this reduced number.        

Tips to Eat More Dietary Fiber (including Whole Grains)

• Breads: Choose breads that list whole-wheat flour, rather than enriched white flour, as one of the first ingredients. Choose bread that contains at least 3 grams of dietary fiber per serving and provide the grams of whole grains on the packaging.*

• Crackers: Choose whole-grain, low-fat crackers with at least 2 grams of fiber per serving.'margin-left:.5in;text-indent:-.25in'> Cereals: Pick whole-grain dry cereals that contain at least 3 to 5 grams of fiber per serving. Mix a few dry cereals together and make one of them a very high fiber bran cereal (>8 grams/sering). Use hot cereals such as oatmeal and oatbran.

• Rice and pasta: Choose brown rice. Buy a whole wheat or grain pasta.

• Legumes: Excellent sources of soluble fiber and resistant starch. Use them in soups, salads, and as side dishes.

• Fruit: Eat at least 2 cups of fruit a day. Limit juice because it contains no fiber.  

• Vegetables: Eat at least 2 ½ cups of vegetables a day.

*Because of the push to eat more whole grains, some manufacturers put the grams per serving on product packages. Additionally some companies purchase a stamp from the Whole Grains Council to help you spot foods with sufficient whole grains.