The Role of Fiber in Our Diet
Dietary fiber is the part of whole grains, bran, vegetables and fruits that passes through the gastrointestinal tract without being digested. As it is carried through the digestive system and out of the body, fiber aids digestion and helps to prevent constipation. It lowers the risk of a number of conditions, such as diabetes, heart disease and colorectal cancer. There are two types of dietary fiber, soluble and insoluble. Fruits and vegetables contain both, though one generally predominates in any given type of food.
As the name suggests, soluble fiber is dissolved by water in the digestive system. It is the viscous part of plants like sap from trees. This type of fibre binds water from the gastrointestinal tract and slows down digestion. Soluble fibre interferes with the absorption of cholesterol from food and thus lowers bad cholesterol in blood. Moreover, it improves functioning of the stomach and enhances insulin sensitivity. Excellent sources of soluble fiber include whole grains, legumes, bran, some fruits such as prunes, pears or apples and many vegetables (for fiber-rich foods check the table below). Oat bran and beans are especially suitable for clearing out the digestive tract by softening bowel movements and stimulating the gastrointestinal system to expel them.
Benefits of Soluble Fiber
- As it was mentioned earlier, soluble fiber lowers the levels of bad (LDL) cholesterol in the blood, thus helping to prevent heart disease.
- It tends to moderate the levels of glucose in the blood and improve insulin sensitivity, which is particularly important for diabetics.
- Soluble fiber makes you feel fuller for longer, while containing no calories, so it is indispensable for anyone wishing to lose weight.
- By stabilizing the digestive tract and the intestinal contractions and normalizing bowel movements it helps to relieve and prevent diarrhea and constipation.
This type of fiber does not dissolve in water and passes through the digestive system in more or less original form. Though insoluble in water, it also absorbs water from your digestive tract. Insoluble fibre adds bulk to the diet and has laxative effect, speeding up the passage of intestinal contents. This variety is present in whole-grain cereals and baked goods, brown rice, seeds, nuts, legumes, unpeeled vegetables, fruits and especially in wheat bran.
Benefits of Insoluble Fiber
- This gut-healthy fiber makes bowel movements bulkier, helping to prevent constipation, diverticulosis and hemorrhoids.
- Insoluble fiber, especially raw wheat bran, may lower the risk of colorectal cancer.
- Just like soluble fiber, it makes you feel full longer, thus controlling overeating and excess weight gain.
How Much Dietary Fiber You Need
The typical Western diet includes only about 15 grams of fiber per day, which is half the amount it should. Research shows that men need about 38 grams (30 grams when over 50) and women 25 grams daily (21 grams when over 50). To obtain all the benefits of dietary fiber, eat a variety of high-fibre foods. Avoid fiber supplements not to lose many additional health benefits that fiber-rich foods can offer. When adding more fiber to your diet, do it slowly so that bacteria in your gastrointestinal tract can adjust to the change. This will help you prevent gas and diarrhea. Keep in mind that too much fibre at once can cause gas, bloating and abdominal cramping. Drink plenty of liquids because dietary fiber absorbs water. Drinking six to eight large glasses of water or other liquids every day will help the fiber move through your digestive tract painlessly.
Given the large variety of fiber-rich foods, you should not have any problem adding more fiber to your diet. The main reason why so many people associate dietary fiber largely with bran is a series of advertising campaigns for bran cereals and muffins, which hit the media when studies, suggesting that dietary fiber could help prevent cancer, were released.
Here is one example of how whole grains can make the difference. A slice of whole-wheat bread contains 1.4 grams of fiber, about three and a half times as much as a slice of white bread. A cup of whole-wheat spaghetti contains 3.9 grams of fiber, three times more than a cup of regular spaghetti. Half a cup of brown rice contains a gram of fiber, which is even five times as much as the same amount of white rice. One easy way to add more fiber to your diet is to sprinkle three tablespoons of raw wheat bran on your meal once every day.
Where to Get More Information: The World’s Healthiest Foods