If anything is a “free food,” fiber is. While fiber is a carbohydrate, it won’t raise our blood glucose. In Europe, in fact, it’s not even counted as a carbohydrate, which can confuse us when we study the nutrition labels on those products.

In the second sentence above I almost wrote that fiber has no effect on our blood glucose. But that’s not true. Fiber actually helps us to control blood glucose spikes.

Fiber doesn’t have any available carbohydrate that can be digested. Some people refer to available carbohydrate as “glycemic” or “usable” “net” carbohydrate, or “nutritive” carbohydrate. All of these terms refer to the same thing.

Except for fiber supplements, nothing that we eat is all fiber. Even oat bran has some protein, fat and available carbohydrate.

All plants that we eat for food – including fruits, vegetables, grains and beans – have some fiber. The key word here is plants. There isn’t any fiber in meat, poultry, seafood, dairy products, eggs or fats.

Except for some vegans, almost none of us get enough fiber in our diet. On average, American women get 12 grams per day; American men get 18. The experts say that we should get from 25 to 40 grams per day.

When we start taking fiber seriously, we have to take it slowly. If you increase your fiber load too rapidly, it will cause intestinal distress.

We can categorize fiber in several ways. Until now, the most common way was by type – how easily it dissolves in water. Soluble fiber partially dissolves in water. Insoluble fiber does not dissolve in water. Dietary fiber is the name for these two types together.

We need a balance of soluble and insoluble fiber. But soluble fiber, in particular, has several major benefits for people with diabetes. By delaying stomach emptying, it slows the digestion of starches and sugars and thereby reduces blood glucose spikes. It also decreases the level of cholesterol in our blood, which reduces our risk of heart disease, the main complication of diabetes. Both of these types of fiber fill us up without adding calories.

Oatmeal and oat bran have most of the good publicity about their fiber. That’s because about half of their fiber is soluble. And that’s why the Food and Drug Administration has allowed a health claim on oat products. But recently the FDA allowed that claim on barley products too, because half of its fiber is soluble. Most foods have much less of their fiber in soluble form.

Another way to categorize fiber is by its source – whether it is from grains, vegetables, fresh fruit, dried fruit and nuts and seeds and beans. A new study of French adults – who are certainly quite like American adults in spite of the different way that they talk – conclusively shows how important it is for us to get our fiber from a variety of these sources.

This huge study followed 2,532 men and 3,429 women for up to eight years. This research appeared in the December 2005 issue of The American Journal of Clinical Nutrition. It focused on several of the known risks for heart disease.