Dietary Fiber - Not A Nutrient, But Important For Digestive Health (part 2)
In our last Health Science News Page, we discussed the body’s requirements for fiber and presented dietary sources. Although dietary fiber is not defined as a nutrient, and the body does not digest or absorb it, dietary fiber has a critical role in the prevention of diseases and maintaining health.
Dietary fiber is classified as either soluble or insoluble. Soluble fibers dissolve in water and form a gel like substance in the digestive system which slows the digestive process and prevents excessive absorption of starches and sugar from foods. Water insoluble fiber absorbs water and helps create bulkier stool. Dietary fibers comprised of complex substances such as cellulose and hemicellulose - which are present in almost every plant - are water soluble fiber. Another such substance is pectin which is abundant in fruits and vegetables. Other fiber such as lignin is insoluble in water; and psyllium and natural gums have high water absorption capacity.
How dietary fiber works in our body:
Binding Capacity: Fiber rich foods have to be chewed longer, and need more water for digestion and they thereby attain higher volume in the digestive system (giving a feeling of fullness) and help soften the stools. Fiber also stimulates intestinal movements and blood circulation in the digestive system and favors the growth of healthy bacteria.
Some water insoluble fibers can bind various minerals, trace elements, dietary enzymes, and bile acids enhancing the extent and speed of their digestion and absorption. These fibers also bind to excess dietary fats, cholesterol, sugars and other harmful substances and enhance their elimination from the body.
Water solubility: Some water soluble fibers such as pectins, natural gums, and cellulose are rapidly processed by the intestinal bacteria which extracts the nutrients they need from them. Therefore, the fibers support the growth of healthy bacteria in the gut. The metabolic processes involved in the disintegration of dietary fibers by these bacteria help balance the intestinal pH and stimulate elimination of toxins. Healthy bacteria in the digestive system also promote and strengthen the immune system and help in the absorption of other nutrients. More than 80% of human immunity depends on the health of the digestive system.
Since the dietary fibers produce bulk and increase the volume in the digestive system, it gives a feeling of fullness for a longer time than most other foods and increases stool volume. This helps in prevention of obesity as well as constipation. Because of their role in transport and appropriate metabolism and elimination of fats and sugars, the dietary fibers help in prevention of some aspects of metabolic syndrome such as high blood sugar, high cholesterol, and cardiovascular diseases. Dietary fibers are also proven to reduce the incidence of colon cancer due to their properties of binding to dietary carcinogens and facilitating their rapid excretion. Healthy intestinal bacterial growth, which is stimulated by dietary fiber consumption, helps in degradation of carcinogens like ammonia and other toxic substances.
Therefore, although dietary fibers are not absorbed, they are of immense importance for disease prevention and by affecting a variety of metabolic processes, they contribute to the healthy function of our body.