Why Fiber Is Important
Fiber, or roughage, is composed from plants' cell wall material. Whole grains, legumes (dried beans and peas), nuts, and vegetables are all good sources of dietary fiber. Fiber is considered a carbohydrate, but since we cannot digest the majority of fiber, it does not effectively contribute to a rise in blood glucose levels. In fact, dietary fiber is an important nutritional tool in normalizing blood glucose levels because it slows digestion and therefore the absorption of accompanying nutrients.
How It Works
When viscous (water-soluble) fiber absorbs water in the gastrointestinal tract, it turns to a gel-like, substance that helps to normalize blood glucose and insulin levels by slowing the passage of food through the intestines. The delay in nutrient absorption means a slower and more stable rise in blood glucose levels.
Because it absorbs the excess intestinal bile acids that help to form cholesterol, soluble fiber helps lower blood cholesterol levels, another important consideration in people with diabetes who are at risk for cardiovascular disease.
Always consume plenty of water or noncaffeinated beverages — at least 2 liters, or around eight glasses, daily — if you are eating a fiber-rich diet. Fiber without adequate fluids can lead to constipation. Increasing fiber intake slowly can also help to ease any bloating or other unwanted gastrointestinal distress.
Another benefit is that viscous fiber improves satiety, or the feeling of fullness you get when eating a fiber-rich meal. It delays stomach emptying, and in those people with type 2 diabetes who are also overweight, satiety can be a useful tool for weight loss.
A diet high in low-glycemic whole-grain cereal fiber has been found to have a beneficial effect in controlling postprandial (after-meal) blood glucose levels and reducing serum cholesterol levels in people with type 2 diabetes. And some studies have shown a glucose- and lipid-lowering benefit with fiber intake of up to 50 grams daily.
In the United States, carbohydrate information on food labels includes total dietary fiber. When counting carbs for the nutritional management of diabetes, total grams of dietary fiber should be subtracted from total carbohydrates in those foods that contain more than 5g of fiber per serving.
The ADA recommends a daily fiber intake of at least 14 g per 1,000 calories. Talk to your doctor and dietitian about what level of fiber in your diet is right for you.
Fiber intake has also been associated with a reduction in diabetes risk in a number of studies. One of these, the six-year Nurses' Health Study involving more than 65,000 participants, found that women on a low-fiber diet heavy in processed, sugary foods were 2.5 times more likely to develop type 2 diabetes than those who ate at least 25 grams of fiber daily.