Fiber is a substance found in plant foods - whole grains, fruits, vegetables, beans, nuts and seeds - that the body cannot digest. Fiber, also referred to as dietary fiber, essentially has no calories, because it is not absorbed by the body. Instead, it passes through the digestive system largely intact.

Fiber is generally separated into two groups based on its solubility (ability to dissolve) in water. Soluble fiber turns to a gel when mixed in a fluid. For instance, gums and pectins are soluble fibers and are found in beans, oats, barley, and some fruits and vegetables. Insoluble fibers, such as cellulose and hemicellulose, do not dissolve in liquids and are typically found in most whole wheat and grain products, in addition to vegetables.

Fiber is found in plants. It is not present in animal products such as milk and other dairy products, eggs, meat, poultry and fish. Sources of fiber include:

• Skins
• Membranes
• Seeds
• Bran

Foods with high fiber content include:

• Whole-grain cereals and breads
• Fruits
• Vegetables
• Legumes (dried peas and beans)

The benefits of soluble fiber include:

• It dissolves in water, turning into gel. This slows the digestion and absorption of nutrients, and allows glucose to be slowly and steadily released into the bloodstream.
  
  
• It soaks up excess bile acids in the intestinal tract. Bile acids are made in the liver from cholesterol. A type of soluble fiber called pectin binds to fatty substances in the digestive tract. Bile acids bound to fiber are excreted in the stool. This causes more cholesterol to be used to make bile acid, leading to an overall lowering of blood cholesterol levels.
  
  

  

• It delays stomach emptying, which makes a person feel full (satiated).

Insoluble fiber (also known as roughage) helps to regulate gastrointestinal functions, keeping the colon clean. It cannot be dissolved, and instead pushes waste through the intestines.

Fiber is a key element of a healthy diet. It can help contribute to good digestive health and appetite control, while also playing an essential role in the prevention or management of many digestive disorders, including constipation, hemorrhoids, diarrhea, irritable bowel syndrome, fecal incontinence, gallstones, diverticular disease and colorectal cancer. Research also indicates that a high-fiber diet may help prevent or manage other conditions such as diabetes, obesity and heart disease.

Foods high in fiber, such as fruits, vegetables and whole grain foods are naturally cholesterol-free and generally low in fat, sodium and calories (energy). In addition, these foods are full of vitamins and minerals, carbohydrates and protein, all of which have a significant impact on an individual’s health, especially that of the digestive system.