While fiber doesn't provide any energy, nor does it contain vitamins or minerals, it's nevertheless an important part of the human diet. Appropriate fiber intake helps maintain the health of the digestive tract and even enhances cardiovascular and other system health. Adequate fiber intake can help alleviate or prevent digestive problems, though it can also lead to certain digestive symptoms.
Fiber Chemistry
Chemically speaking, fiber is actually very similar to starch. Both are made up of long chains of small molecules called monosaccharides -- specifically, the monosaccharide glucose. The difference between fiber and starch is only in the shape of the bond that connects the glucose molecules to one another. As a result of the bonds, humans can digest starch but can't digest fiber.
Fiber Function
In the body, fiber plays many important roles. It slows the rate of digestion and absorption of food, helping to regulate blood sugar. It absorbs toxins and cholesterol in the intestine and prevents absorption of these molecules. As such, high-fiber diets can help lower blood cholesterol, which increases cardiovascular health. Finally, fiber promotes a feeling of fullness and helps maintain a healthy weight.
Too Little Fiber
A number of digestive complications can arise from too little fiber in the diet. Chiefly if you don't get enough fiber in your diet you're more likely to experience constipation or irregularity of bowel movements. This can lead to overextraction of water from your bowel movements, meaning that they become quite hard and difficult to pass. As a result, you are at increased risk of hemorrhoids and rectal tearing.
Fiber Concerns
Though fiber is healthy, increasing your intake of fiber dramatically over a short period of time can also cause digestive distress. While you don't digest fiber, bacteria in your lower intestine do. They produce, as byproducts of digestion, large quantities of gas. This can lead to intestinal bloating and cramping, particularly in individuals who aren't used to getting much fiber in the diet. It's best to increase your daily fiber consumption slowly.
Expert Insight
Certain individuals benefit particularly from fiber. Pregnant women, for instance, have a tendency to become constipated because the hormones of pregnancy slow the rate of digestion. Eating plenty of fiber during pregnancy can help keep your gut moving more regularly, which decreases the risk of constipation and related digestive issues. Fruit, vegetables, whole grains, and beans are all sources of fiber. Drinking plenty of water helps distribute fiber throughout the gut and also reduces the likelihood of constipation.
References
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
- "Anatomy and Physiology"; Gary Thibodeau, Ph.D.; 2007
