Ironically, health professionals recommend a high-fiber diet at least partly because the body cannot digest or absorb fiber; unlike fats, proteins and other components of a diet, fiber exits the body relatively intact. In doing so, however, it may help ease constipation, maintain a healthy weight and lower the risk of various diseases. According to the Centers for Disease Control and Prevention, a healthy adult diet includes 14 grams of fiber for every 1,000 calories consumed.
Regulate Bowel Movements
The term fiber refers to the indigestible plant parts, or "roughage," found in whole grains, fruits, vegetables, nuts and legumes. Instead of absorbing or digesting fiber, the body simply excretes it as waste. By increasing the amount of fiber you eat, you increase the bulk of stool that must exit. However, fiber also absorbs water as it passes through the digestive tract, which softens the bulk and makes it easier to pass.
Maintain Healthy Bowels
As a fiber-rich diet results in more regular, less problematic bowel movements, the bowel itself becomes healthier. When constipation is alleviated, often hemorrhoids heal as well. High-fiber intake also may ease or prevent other intestinal ailments, such as irritable bowel syndrome and diverticulitis.
Satisfy the Appetite
Fiber contains zero calories. Your body does not absorb it and therefore cannot burn it as fuel or store it as fat. Your stomach does not realize this, however, and will register as full even if the fiber content is useless for manufacturing energy. Fiber-rich foods also tend to be lower in calories, so you can consume them in greater volume, which adds to meal satisfaction. Likewise, high-fiber foods often require more chewing, which allows time for you to enjoy the textures and tastes and your body to register its fullness. These factors may help you resist overeating, maintain a healthy weight and even lose excess weight.
Regulate Blood Sugar
Someone diagnosed with diabetes experiences sustained high levels of blood sugar because his body does not produce enough insulin to neutralize it or cannot use the insulin it does produce. Consumption of soluble fiber -- found in oats, peas, citrus fruits, apples, beans, carrots, barley and psyllium -- slows the body's absorption of consumed sugar, which helps to moderate changes naturally in blood sugar levels. According to MayoClinic.com, a diet high in insoluble fiber -- found in whole-wheat flour, wheat bran, vegetables and nuts -- is linked with a reduced risk for developing type 2 diabetes, the most common form of the disease.
Lower Cholesterol
Consumption of soluble fiber -- such as that found in oats, beans and flax seed -- also lowers levels of "bad" cholesterol, or low density lipoproteins (LDL), in the bloodstream. The body uses cholesterol to produce bile acids, some of which are excreted each day. However, dietary fiber tends to bond with bile. According to the American Dietetic Association, this may result in the body excreting more bile than usual -- and using more cholesterol than usual to replace that lost bile, thereby reducing cholesterol levels in the body.
Protect the Heart
In someone with heart disease, cholesterol-filled plaque builds up on the walls of the arteries leading to the heart. This hardens them and may eventually block them altogether, resulting in a heart attack. A high-fiber diet that helps to lower this bad cholesterol and alleviate other risk factors -- such as obesity, diabetes and high blood pressure -- helps fight heart disease.
Potentially Fight Cancer
Traditionally, health professionals have recommended a high-fiber diet to lower the risk of developing colorectal cancers. They based this recommendation on a comparison of the diets and cancer incidences of different countries and a belief that increased bowel traffic eliminates wastes more quickly, thereby reducing exposure of the intestines to any ingested carcinogens. However, in a 2008 position paper discussing the health benefits of fiber, the American Dietetic Association called any evidence linking high-fiber diets with decreased cancer incidence "mixed" and suggested the need for further research on the subject.
References
- MayoClinic.com; Dietary Fiber: Essential for a Healthy Diet; November 2009
- Colorado State University Extension; Dietary Fiber; J. Anderson, et al.; December 2010
- Harvard School of Public Health: Fiber: Start Roughing It
- "ADA Reports"; Position of the American Dietetic Association: Health Implications of Dietary Fiber; Judith A. Marlett, PhD, RD, et al.; July 2002
- American Dietetic Association; Health Implications of Dietary Fiber; October 2008
- Harvard School of Public Health: Fiber and Colon Cancer: Following the Scientific Trail
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