Fiber (sometimes writer as fibre) has several meanings
in the field of medicine but is most commonly used to
refer to dietary fiber. Dietary fiber is a term for chemical
substances in the cells of plants that cannot be digested
by the human body. Each of the different types of dietary
fiber has different effects on functions of the digestive
tract, such as water absorption, and fat metabolism.
Metabolism is a chemical process in the body by which
food is broken down and changed to energy.
WHY CAN'T THE HUMAN BODY DIGEST DIETARY FIBER?
Dietary fiber cannot be digested by humans because they lack the necessary
enzymes (proteins that help produce chemical reactions). More specifically, dietary
fiber is resistant to hydrolysis. Hydrolysis is a process in which a substance is broken
down by splitting its bond and adding water to it.
Because dietary fiber cannot be digested, it passes through the body virtually
unchanged and cannot be used as an energy source. Although humans cannot digest
dietary fiber, some of it is broken down by bacteria to produce gas and acids.
WHAT ARE THE BENEFITS OF EATING FOODS WITH DIETARY FIBER?
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WHAT FOODS ARE GOOD SOURCES OF DIETARY FIBER?
Dietary fiber can be found in leafy green vegetables, such as
cabbage, lettuce, spinach, celery, salads, carrots, turnips, and
potatoes. It can also be found in raw and cooked fruits, cereals,
peas, beans, and whole-grain foods.
Over the counter dietary fiber supplements and dietary fiber pills are
available that provide an extra source of fiber to the diet. Metamucil,
Citrucel, and FiberCon are examples of such products.
WHAT IS DIETARY FIBER MADE OF?
Dietary fiber adds bulk (mass) to the diet and helps prevent disease of the intestine (e.g., colon). The
intestine is a tube shaped structure that is part of the digestive tract. It is divided into the small and large
intestine. Fiber also decreases the amount of pressure in the colon. The colon is the major part of the
large intestine. Dietary fiber also helps prevent constipation (difficulty pooping) because it helps move the
intestine, which, in turn, helps move poop out of the body. Dietary fiber also helps prevent constipation by
adding bulk to the feces by removing water from it. By making the poop larger, dietary fiber helps it move
through the intestines more easily. To keep the bowel healthy, a person should eat several servings of
dietary fiber each day.
The main substances that make up dietary fiber are gums and pectin (thick, jelly-like substances found in
fruits and vegetables), as well as lignin, cellulose, and hemicellulose. The last three substances form the
main structure of plant cell walls. These five substances provide a plant with a structure that is partially
rigid, yet stable.
WHAT ARE OTHER DEFINITIONS OF FIBER?
Fiber is also used to refer to:
1. The part of a nerve cell that is responsible for sending impulses and is surrounded by cells known as
Schwann cells or by a supportive substance known as glia. A good example of nerve fibers would be
2. Flexible, threadlike objects found outside of cells. An example would be connective fibers found in
tissues of the body.
3. Long cells, such as muscle cells.
4. A thin thread or thin, flexible threadlike object.
WHAT ELSE IS DIETARY FIBER KNOWN AS?
Dietary fiber is also known as fiber, bulk, and roughage.
WHAT IS THE ORIGIN OF THE WORD “FIBER?”
Fiber is also written as fibre. Fiber comes from the Latin word “fibra” meaning “thread.”