Fiber: a healthful, necessary part of any diet

Fiber contains no calories and is not a nutrient, but is vital for good health. A complex carbohydrate, fiber comes from the edible parts of plants and cannot be digested, absorbed into the bloodstream or used by the body for energy. There is no dietary fiber in meat or dairy products.

There are two types of fiber, soluble and insoluble. Some foods contain both types. Generally, vegetables have more insoluble fiber and fruits contain more soluble fiber.

Soluble fiber dissolves in water and develops a soft, mushy texture when cooked. Sources include dry beans and peas, lentils, whole oats, oatmeal, oat bran, ground barley, flaxseeds, many vegetables and fruits, and psyllium seeds.

Insoluble fiber does not dissolve in water but can absorb water. It has a tough, chewy texture. Sources are whole-wheat products, wheat bran, oat bran, corn bran, flaxseeds, many vegetables, fruits with skins, root vegetables and legumes.

Over the course of a lifetime, a low-fiber diet (less than 20 grams per day) can result in numerous health problems including:

• Constipation

• Hemorrhoids

• Obesity

• Elevated cholesterol

• Elevated blood sugar levels

A high-fiber diet (20 to 35 grams per day) may lower the risks for:

• Hemorrhoids

• Heart disease

• Obesity

• Type 2 diabetes

• High cholesterol

• Certain types of cancer

Foods high in soluble fiber help to lower LDL ("bad") cholesterol without lowering HDL ("good") cholesterol.

Soluble fiber also helps to lower or stabilize blood sugar levels by slowing the rate at which carbohydrates break down and glucose is released into the bloodstream; therefore, it plays a role in the prevention and treatment of type 2 diabetes.

In addition to promoting regularity, fiber helps children establish eating patterns that may reduce the risk of developing heart disease and some types of cancer later in life.