Talking to Your Diabetes Patients About Fiber

Author: Amy Brian, PharmD, CGP, CPP

Achieving an optimal diet in the patient with diabetes is not an easy task. Individual meal planning with a nutritionist or diabetes educator is often necessary. However, all pharmacists can make some general recommendations to their patients with diabetes with regard to fiber intake. While most of us recognize that fiber is an essential part of a healthy diet, we may not understand exactly what role fiber plays in our health. In diabetes, fiber has 2 key roles: stabilization of blood glucose and lowering of cholesterol.

There are 2 types of fiber, soluble and insoluble. Both types provide different and important benefits for our bodies. Soluble fiber, made of substances such as pectin, forms a thick gelatin-like compound when dissolved in liquid. In the intestinal tract, this gel binds with bile acids and cholesterol and removes them from the body, which results in reduced cholesterol levels. Soluble fiber also slows down the absorption of carbohydrates and can result in a more stable rise in blood glucose after a meal. Soluble fiber is found in foods such as oats, oatmeal, broccoli, asparagus, dried beans, soybeans, and certain fruits including pears, apples, oranges, and berries.

Insoluble fiber absorbs water as it moves through the intestines, which results in bulk stool formation and increased transit time. By moving stool through the intestines more quickly, conditions such as constipation and diverticulosis can be prevented. It is also believed that the risk of colon cancer is decreased when intestinal transit time is quicker since toxic substances are removed more quickly. Insoluble fiber is found in wheat products, beans, grains, and a lot of fruits and vegetables.

Fiber is a type of carbohydrate, but since it is not absorbed or broken down by the body, it contributes no caloric value. Some diabetic patients use carbohydrate counting as their primary means of postprandial blood glucose control. In some cases, fiber can actually be subtracted from the total grams of carbohydrate when calculating carbohydrate total for a particular meal. The current recommendation for daily fiber intake for most individuals is 20 to 35 g. However, most studies indicate that Americans typically receive only 10 to 12 g of fiber per day. Some small-scale studies indicate larger amounts of daily fiber can be beneficial for patients with diabetes. One study published in the New England Journal of Medicine demonstrated that patients with diabetes had better blood glucose control with a high-fiber diet of 50 g per day, versus those on a moderate-fiber diet of 24 g per day. At 6 weeks, the group of patients on the high-fiber diet demonstrated a mean reduction in daily preprandial glucose of 13 mg/dL versus the moderate-fiber group. The patients randomized to the high-fiber group also demonstrated significant lipid profile improvements as well. Total cholesterol concentrations were lowered 6.7% and triglyceride concentrations 10.2%.

Large-scale studies are lacking, but enough data are certainly present to realize the importance of working with our patients with diabetes on improving fiber intake in their diets. Most patients, when asked, will state that the importance of fiber is to "keep them regular."As pharmacists, we can explain that the benefits of fiber extend far beyond regular bowel movements. In addition to promoting a feeling of fullness, remind them that fiber has beneficial effects on both blood glucose control as well as cholesterol profiles.

Good counseling points for patients trying to increase fiber in their diets include:

Dr. Brian is a clinical specialist with Cornerstone Health Care, High Point, NC.