Fiber or roughage is the indigestible part of our food that plays an important part in health. Dietary fiber is found naturally in the plant parts that we eat. They are not digested but just pass through our system, absorb water, and aid in bowel movement. We all have heard that fiber is important, but might not be clear about what fiber should we eat, how much should we consume, and the benefits of having more of dietary fiber.
Dietary fiber is grouped into two types – soluble and insoluble.
Soluble fiber dissolves in water while insoluble type does not. Functions of the fiber in the body are based on this solubility property.
Soluble fiber absorbs a good amount of water in the digestive system and becomes gelatinous. It slows down the rate of digestion and also the time taken for food to be emptied from stomach. This gives a full feeling for a longer duration as the food remains in the system for more time. It is this property of soluble fiber that makes it a good candidate for weight reduction. As emptying of food from the stomach is slowed down, absorption of sugar is also reduced, thus affecting the blood sugar levels. Soluble fibers thus help in controlling diabetes. Soluble fibers also reduce the rate of absorption of fatty acids which aids in lowering of cholesterol levels.
Some rich sources of soluble fibers include oatmeal, lentils, fruits like oranges, apples and pears, nuts, flaxseeds, cucumbers, celery, and carrots.
Insoluble fiber, on the other hand, adds bulk to the food in the digestive system. It helps to move the food through the tract and prevent constipation. They increase the speed of movement of food and waste in the digestive system and promote regular bowel movement. Insoluble fibers also help in maintaining the pH of the intestine.
Insoluble fiber can be obtained from whole grains, whole wheat, wheat bran, brown rice, vegetables like cabbage, carrot, leafy greens and cucumbers, and also from grapes, corn bran, and nuts.
As per dietary guidelines, women below the age of 50 years and teenage girls should ideally get 25 grams of dietary fiber in a day. Teenage boys and men below the age of 50 should get up to 38 grams of fiber per day. One need not worry about what type of dietary fiber is in your diet unless you are specific about the need.