Fiber, a nutrient once associated with powder supplements aimed at older populations, is now making the rounds as one of the latest “It” nutrients, with food manufacturers adding it to everything from white bread to Froot Loops. Assumably, this is because consumers are becoming increasingly aware of fiber’s health benefits and are demanding it; however, most people have little idea what it actually does in the body.
When we understand how dietary fiber functions after we’ve eaten it, it starts to make sense that we can eat almost unlimited quantities of foods rich in fiber without gaining weight.
What is Fiber?
Found only in plant foods, fiber is a polysaccharide (carbohydrate) that cannot be digested and absorbed by humans. It comes in two forms: soluble (dissolves in water) and insoluble (cannot dissolve in water). Soluble fiber ferments in the large intestine before passing and therefore can contribute an insignificant number of calories to the diet; insoluble fiber passes through the digestive tract virtually unaltered. Soluble fiber is found in foods like fruits, vegetables, legumes, and some grains like oats and barley, while insoluble fiber is found in whole grains, nuts and seeds, and the skins of fruits and vegetables.