By Gerda Hope


Dietary fibers are a part of plants that are resilient to digestion. They are compound starches, classified based on their solubility in water. Solvable fibers (pectins, gums, mucilages) dissolve in water, and effect the absorption of sugar, fat and other nutrients. Insoluble fibers (cellulose, hemicellulose, and lignin), which are not solvable in fluids, contribute more to an greater stool weight and shorter transit time.

According to the guidelines, an average American man should consume 30 to 38 grams of dietary fiber per day while a woman should consume between 21 to 25 grams of dietary fiber per day. However, the actual intake of dietary fiber is much lower than recommended. It is thought that women are consuming only 13 grams and men's consumption is just 17 grams of dietary fiber per day.

Researchers believe that soluble fibers form a gel in the stomach leading to sluggish gastric emptying and a higher rate of absorption of the nutrients. This increases satiety and leads to lower food intake which is reflected in reduced weight gain. Moreover, fermentation of fiber in the large intestine leads to reactions which finally reduce the serum cholesterol levels.

Major studies have shown that higher fiber consumption, especially water soluble fiber, is associated with a decline in coronary heart disease risk. An investigation of ten studies detected a 12% fall in the risk for coronary events and a 19% decline in the risk of death for each 10 g increase in dietary fiber per day.

The National Cholesterol Education Program recommends an intake of 5 to 10 g of soluble fiber per day to improve LDL-C (low density lipoprotein) levels. The American Heart Association (AHA) recommends a total dietary fiber intake of 25 to 30 g/d from foods, not supplements, to ensure nutrient adequacy and to maximize the cholesterol-lowering impact of a fat-modified diet.

Several studies have shown that a high fiber intake could decrease blood pressure. One study showed that the effects of fiber intake were more pronounced in older than younger patients. High fiber consumption could also lessen blood cholesterol levels.

Fiber intake could cause increased bloating. But, the severity of the side effects is restricted when fiber intake is reduced. Fibers that are less fermented, such as psyllium, may also benefit in this regard. Drinking appropriate amounts of fluid and slowly increasing the amount of fiber consumption could also limit bloating.

High fiber intake could interfere with the absorption of minerals, such as iron, zinc, magnesium, and calcium.




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