Fiber isn’t a single nutrient but a family of plant-based nutrients that are generally resistant to human digestion. Since plants lack the bony skeletal design that provides much of an animal’s shape and form, fibers provide much of the structural support to plant cell walls and the plant in general. Plants also use certain fiber as the foundation for their scar tissue. It is important to remember that while humans and other mammals prefer to produce proteins like collagen as the structural basis of their bodies, plants use carbohydrates.
Fiber consists of non-starch polysaccharides such as cellulose, hemicellulose, gums, mucilages, pectin, and oligosaccharides along with other plants components such as lignin. Chitin is often considered a fiber because it is a polysaccharide. Chitin is found in the exoskeletons of shellfish such as lobster, shrimp and crab as well as some insects such as beetles and ants as well as in the cell walls of some yeast and fungi. Table 4.6 lists fiber content of certain foods.
Fructooligosaccharides (FOS), which are sometimes called oligofructose or oligofructan, are short links of fructose terminating in glucose. Inulin is similar to FOS, however the number of fructose molecules linked together can exceed 100. Both inulin and FOS are found in many plants including Jerusalem artichoke, burdock, chicory, leeks, onions, and
asparagus. FOS and inulin are often used as food additives as they addbulk and mild sweetness to foods while having health promoting properties.
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