| Updated at: 1645 PST, Tuesday, January 18, 2011|
LONDON: Dietary fiber is a carbohydrate that the body cannot digest or absorb. Also known as roughage or bulk, it passes largely undigested through the stomach, small intestine, colon and out of the body. There are two classifications of fiber: insoluble fiber which cannot be dissolved in water and soluble fiber which can be dissolved. Found mostly in plant sources like fruits, vegetables, grains and legumes, fiber is essential for maintaining health and plays an important role in the digestive process.
Insoluble fiber can be found in whole grain products, dark leafy vegetables, green beans, wheat bran, corn bran, seeds, nuts and in the skins of fruits and vegetables. During the digestive process insoluble fiber draws water to the intestine, increasing the bulk and softness of waste products. This prevents constipation and promotes regular bowel movements by encouraging the movement of waste through the intestines. Another benefit of insoluble fiber is that it controls the intestines' pH balance. Through the regulation of pH levels, insoluble fiber may prevent microbes from producing cancerous cells in the colon.
Soluble fiber is found in foods like oats, nuts, seeds, legumes, sweet potatoes, apples, pears, plums, flax seed, prunes, berries, dried beans and peas. Unlike insoluble fiber which cannot be digested at all, soluble fiber can be digested slowly. Soluble fiber prolongs the digestive process and keeps the stomach fuller longer; this slows the absorption of carbohydrates and sugar into the body. The slow absorption of carbohydrates leaves the body feeling fuller longer while the slow absorption of sugar gives the body an opportunity to regulate blood sugar levels.
Dietary fiber plays a vital role in digestive health. As fiber moves waste through the digestive tract, it carries various toxins along with it. This can reduce the risk of developing hemorrhoids and diverticular disease. Furthermore, there seems to be a link between the fermentation of soluble fiber and colon health. Diets high in fiber can also protect heart health since they seem to lower total blood cholesterol levels, by lowering low-density lipoproteins.
Another benefit of foods high in fiber is that they can aid in weight loss. Because fiber slows down the digestive process, it leaves you feeling fuller longer, reducing the likelihood of snacking in between meals. High fiber foods also tend to be less energy dense than most foods, meaning that they contain fewer calories than more nutrient-rich foods like proteins, fats and carbohydrates. They also require more chewing time, giving the body more time to register when it is no longer hungry.
A diet rich in fruits, vegetables and whole grains is essential to meeting the recommended daily insoluble and soluble fiber requirements. It is generally recommended that the daily intake of fiber be around 25 g per day; 75 percent of this should be insoluble fiber and 25 percent should be soluble fiber. Since many foods like oats and flax seeds contain both soluble and insoluble fiber, a well balanced and healthy diet will typically meet the daily fiber requirements.