Fiber: Super-hero or villain - Part 2

Yesterday I left you hanging with regard to how you measure insulin response and the role of fiber. 

One way to measure the insulin response of carbohydrate is by measuring fiber content. But since most people do not have the time to measure the amount of fiber they are eating daily, an alternative and more accurate method is to become familiar with the glycemic index of foods. The glycemic index measures the rate of entry of glucose into the bloodstream, thereby providing a good indication of insulin response. Carbohydrates are categorized on a scale of 0 to 100. The index ranking is divided into 3 categories: low, medium and high. Foods that are lowest on the scale, have the slowest rate of entry into the bloodstream and the lowest insulin response. Fiber to the rescue: adding more fiber to your diet has many benefits to your health. As a rule, complex carbohydrates such as fruits, vegetables, whole grains, and legumes provide excellent sources of energy without creating dramatic fluctuations in glucose levels. Complex carbohydrates which have low to medium GI also tend to have higher fiber content. 

In addition to affecting blood glucose, fiber has other roles. The colon requires bulk in order for the bowel to move 2 to 3 time per day. The right kind of fiber is critical to adding proper bulk. Optimal intake for most people is 30-40 grams per day. The source of fiber should be split evenly between soluble and insoluble fiber. A mixture of flaxseed and borage seed fiber provides a balanced combination. Because it can be difficult for some people to eat 30 to 40 grams of fiber per day, many people opt for fiber supplements. It is important to avoid predominantly soluble fiber such as psyllium because it absorbs 40 times its weight in water. The colon needs free water to perform peristalsis, the natural wave-like movement of the colon. Constipation is often caused by dehydration. That is why many people become clogged up when they use a psyllium-based fiber supplement.

That is one dark side to fiber, getting too much soluble fiber. There is another. While fiber is necessary for bulk and a healthy colon, coarse fibers function more as an intestinal rake than the traditional image of the intestinal broom, which has been said to sweep debris from the intestine. Too much scratchy fiber irritates the ileocecal valve. The ileocecal valve is normally closed, keeping the food being absorbed in the small intestine from the bacteria in the large intestine. You can see that if this valve does not function properly, potentially harmful microbes that normally live in the large intestine can flow backwards into the small intestine and interfere with healthy absorption. The small and large intestine are completely different environments that perform separate functions (and they need to be kept separate for good health). If the digestive system is working properly, the two never meet. The ileocecal valve will continue to function properly by eating a high-fiber diet and drinking plenty of fresh, clean water.

As with most things nutritional, balance is the key. When too much scratchy fiber irritates the ileocecal valve, greater quantities of toxins get into the blood. As the valve becomes increasingly sensitized a number of signs or symptoms may appear: irregular bowel movements, such as constipation and diarrhea; tenderness in the lower right abdomen; a sense of fullness after eating small amounts; and gas or bloating. Many of these symptoms could worsen after eating high fiber foods such as bran or raw vegetables, or irritating spices.

Is fiber a super-hero or a villain? Fiber is a super-hero for most people. But as with most things nutritional, it is not always black and white. Fiber is a necessary and important part of a healthy diet. A balance of soluble and insoluble is optimal for most people: however, too much soluble fiber and not enough water can cause constipation; too much scratchy fiber can irritate the small intestine especially those who have Inflammatory Bowel Disease, a category of diseases of the bowel.

These are my own conclusions based on the myriad of conflicting information I have read on the subject of fiber and digestion. I hope it helps clear things up more than it clouds the issue. Here is a recap. Both types of fiber are important for health, digestion, and preventing diseases:

• Soluble fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables. It is also found in psyllium, a common fiber supplement.
• Insoluble fiber is found in foods such as wheat bran, vegetables, and whole grains. It adds bulk to the stool and appears to help food pass more quickly through the stomach and intestines.