Fiber is plant matter that cannot be digested by human enzymes.
We consume it whenever we eat whole grains, legumes, fruits, and vegetables.
Because we cannot digest fiber, it moves through the entire digestive system and much of it winds up being excreted in the feces.
Yet, even though our bodies do not absorb fiber, it is important to our health.
Fiber includes a number of chemical substances that have different physical properties and different physiological effects in the body.
Most fibers are carbohydrates.
Lignin is an exception.
It is chemically not a carbohydrate, but it is classified as fiber because of how it behaves in the digestive tract.
Fibers have been traditionally categorized based on their solubility in water.
There are two types of fibers:
Soluble fiber absorbs water and form viscous solutions that slow the rate at which nutrients are absorbed from the small intestine.
Because neither soluble nor insoluble fiber can be digested in the small intestine, they cannot be absorbed and so they travel into the large intestine.
Bacteria in the colon digest soluble fiber to produce gas and fatty acids, small quantities of which are absorbed and affect other functions in the body.
Some soluble fiber and most insoluble fiber are excreted in the feces.
Insoluble fibers do not absorb water and are not broken down by bacteria, but they do increase the amount of material in the intestine.
When insoluble and soluble fibers are consumed together, the increased bulk of the insoluble fiber and the extra water held by the soluble fiber increase the volume of material in the intestine.
The larger, softer mass of material strengthens the muscles of the colon by stimulating peristalsis, which is the rhythmic muscle contractions that propel food through the digestive tract.
A high-fiber diet allows the stool to pass easily and reduces transit time, which is the time it takes for food and fecal matter to move through the gastrointestinal tract.
We consume it whenever we eat whole grains, legumes, fruits, and vegetables.
Because we cannot digest fiber, it moves through the entire digestive system and much of it winds up being excreted in the feces.
Yet, even though our bodies do not absorb fiber, it is important to our health.
Fiber includes a number of chemical substances that have different physical properties and different physiological effects in the body.
Most fibers are carbohydrates.
Lignin is an exception.
It is chemically not a carbohydrate, but it is classified as fiber because of how it behaves in the digestive tract.
Fibers have been traditionally categorized based on their solubility in water.
There are two types of fibers:
- Insoluble fibers do not dissolve in water.
These fibers are derived primarily from the structural parts of plants.
Chemically, they include lignin and cellulose and some hemicelluloses.
Dietary sources of insoluble fiber include wheat bran and rye bran, and vegetables such as celery and broccoli. - Soluble fibers form viscous solutions when placed in water.
The soluble fiber in oats gives cooked oatmeal its thick gelatinous consistency.
Soluble fibers are found in and around plant cells and include pectin, gums, and some hemicelluloses.
Food sources of soluble fibers include oats, apples, beans, and seaweed.
Soluble fibers are often added to foods in processing.
Pectin is used to thicken jams and jellies.
Gums, such as gum arabic, gum karaya, guar gum, and locust bean gum are extracted from shrubs, trees, and seed pods and are added to foods like mayonnaise, yogurt, and cake as stabilizers and thickeners.
Agar, carrageenan, and alginates come from seaweed, and are used as thickeners and stabilizers in foods like salad dressing and ice cream.
Pectin and gums are also used in reduced fat products because they mimic the slippery texture of fat.
Soluble fiber absorbs water and form viscous solutions that slow the rate at which nutrients are absorbed from the small intestine.
Because neither soluble nor insoluble fiber can be digested in the small intestine, they cannot be absorbed and so they travel into the large intestine.
Bacteria in the colon digest soluble fiber to produce gas and fatty acids, small quantities of which are absorbed and affect other functions in the body.
Some soluble fiber and most insoluble fiber are excreted in the feces.
Insoluble fibers do not absorb water and are not broken down by bacteria, but they do increase the amount of material in the intestine.
When insoluble and soluble fibers are consumed together, the increased bulk of the insoluble fiber and the extra water held by the soluble fiber increase the volume of material in the intestine.
The larger, softer mass of material strengthens the muscles of the colon by stimulating peristalsis, which is the rhythmic muscle contractions that propel food through the digestive tract.
A high-fiber diet allows the stool to pass easily and reduces transit time, which is the time it takes for food and fecal matter to move through the gastrointestinal tract.
SHARE
