What are the benefits of dietary fiber?

There are two types of dietary fiber: soluble and insoluble. All fiber-containing foods contain a combination of both, and both are beneficial. Water-soluble fiber helps lower cholesterol by binding with it during digestion and flushing it from your system. Insoluble fiber absorbs water during the digestion process, and thus helps prevent constipation.

Japanese researchers have found an even stronger correlation between dietary fiber intake and rates of colon and colorectal cancers. Study participants with the highest fiber intake had a 27 percent reduced risk for colorectal cancer and a 42 percent reduced risk for colon cancer. Researchers speculate that these results are due to the tendency of insoluble fiber to promote regularity.

Fiber used to be considered a basically useless filler because it’s not a nutrient. Now, however, we know that fiber reduces the risk of many serious health conditions including heart disease, diabetes, obesity, colon cancer, and hemorrhoids. Fiber also makes for good digestion and elimination, which helps your skin look vibrant and healthy.
By some estimates, the average American eats only about one-third of the amount of fiber needed daily for peak health. Be sure you include whole grains, especially bran, in your diet every day and that you eat fruits whole so that you’ll get enough fiber.

Fruits and vegetables are excellent sources of fiber. Most of us do not eat enough fiber. Eating more fiber will reduce your risk of constipation, help cleanse toxins from your colon, reduce potential discomfort, and help your body absorb the important nutrients you are consuming.

Dietary fibers can lower blood pressure, and cholesterol, and insulin; can stabilize blood sugar; can improve gastrointestinal health, and potentially lower cancer risk; and can help produce satiety that facilitates weight control. So they are only important for anyone at risk for conditions that cumulatively affect at least 80% of the entire population!

Fiber is necessary to promote normal peristalsis, the wavelike muscular contractions that move food along the intestinal tract. As fiber passes along, it absorbs water, which softens and bulks up the stool. Higher stool bulk results in softer and larger stools for most people and eases the elimination of stool. With more bulk, pressure in the colon is actually reduced -- it does not have to contract as strongly to propel the stool along. This is important for people who have constipation, since most will benefit by increasing dietary fiber intake. This point cannot be stressed enough. In fact, some constipated people may require more fiber than the recommended 20 to 35 grams per day. Severe forms of constipation may not respond to fiber and require other forms of treatment.

Some people with chronic diarrhea benefit by increased fiber intake, as fiber absorbs water from the stool and increases consistency. The fiber supplement psyllium may be particularly beneficial.

Increased fiber intake can relieve symptoms of hemorrhoids and difficulty cleansing the anal area by improving stool consistency and frequency and by reducing the adherence of stool following defecation. Again, psyllium seems to be especially helpful here.

Finally, diverticulosis of the colon (occurs when small outpouchings, called diverticula, form in the colon wall) is correlated with low dietary fiber intake. A high fiber intake can actually reduce the pressure within the colon and is particularly helpful if constipation is also present. Contrary to popular belief, there is no evidence that small seeds and grains, nuts and popcorn cause complications from diverticulosis.

The physiological effects of dietary fiber impact stool weight and transit time, digestion, lipid metabolism, short-chain fatty acids (SCFA), and intestinal bacterial flora.

The beneficial effects of dietary fiber are:

• Decreased intestinal transit time
• Delayed gastric emptying, resulting in reduced after-meal blood sugar level
• Increased satiety
• Increased pancreatic secretion
• Increased stool weight
• More advantageous intestinal micro flora
• Increased production of short-chain fatty acids
• Decreased serum lipids
• More soluble bile