A: Fiber-containing foods are a mixture of soluble and insoluble fiber. Both types of fiber can aid in digestion and elimination. However, soluble fibers are soluble (dissolve) in water and can bring water into the digestive tract. The soluble fibers allow for slower movement through the digestive tract while reducing constipation and adding some bulk to the stool. On the other hand, insoluble fibers are insoluble in water, not digested, and travel more quickly through the digestive tract. These actions of fiber-containing foods occur before, during, and after colorectal treatment and surgery.

A: This often depends on the side effects from the cancer treatment. Immediately after surgery, an individual may need to reduce the total amount of fiber and then slowly add fiber-containing foods to regulate any diarrhea, constipation, or consistency of the stool.

The goal after surgery or treatment is to work up to a healthy, well-tolerated amount of fiber, which can be similar to a person’s need for fiber before surgery.

There is value to fiber-containing foods, including vitamins, minerals, and numerous phytochemicals. Phytochemicals are a wide variety of compounds produced by plants; phytochemicals provide the flavor, aroma, and color to various fruits, vegetables, whole grains, and other plant foods. For example, the red pigment in a tomato or watermelon is the phytochemical called lycopene; allium plants like garlic, onion, and shallots produce compounds (phytochemicals) that contribute to their aroma and taste. Consuming a variety of plant foods containing these phytochemicals may assist in reducing risk and recurrence of cancer, as well as reducing risk of heart disease, diabetes, and high blood pressure.

A: The fiber found in vegetables, fruits, and grains are a combination of both types of fibers. For example, oats, barley, and dried beans (like black and pinto beans) contain soluble fiber; wheat bran, fruit and vegetable skins, and whole-grain breads contain insoluble fiber.

I encourage people to try a variety of whole, plant-containing foods to get fiber in their diet. Fruits, vegetables, beans and legumes, whole grains and cereals all contain fiber and offer beneficial phytochemicals. The specific foods need to be adjusted for the individual.

A: The value is two-fold. First, the digestive tract contains a layer of muscle and fiber-containing foods keep the digestive tract fit and the individual healthier. Second, altering the types and amounts of fiber after colorectal surgery or treatment can allow an individual to adjust for challenges with either constipation or diarrhea. If the individual requires an ostomy, the individual will need to adjust the type and amount of fiber to assist with thickening the stool.

A: A low-fiber diet for the first six to eight weeks after ileostomy creation or a low anterior resection surgery may be recommended; however, it is important to transition to a well-balanced diet when you are able. A colostomy patient needs to consume adequate fiber and fluid to avoid constipation after surgery and to reduce diarrhea and/or thicken the stool.

Everyone is different, and each individual will have varying experiences. Sometimes a person will find that although a food that worked one day, the same food can be a challenge another day. It is important to remember that anxiety can stimulate the muscular layer of the digestive tract to move faster and create problems. Patience is necessary to explore how these fiber foods will affect each individual’s digestive tract.

A: If too much insoluble fiber is consumed, the individual may have diarrhea because the food is moving too fast for the colon to absorb adequate water. Even though soluble fiber can slow the digestive tract and is often fermented in the colon, fiber-containing food is a combination of both soluble and insoluble fibers so too much of any fiber foods could cause diarrhea.

Also, absorption of nutrients can decrease if food is moving too rapidly through the digestive tract, and an individual can experience bloating, gas, cramping, and a decrease in appetite with too much fiber consumption.

It is best to increase fiber foods gradually so the body can adjust to it.

A: If an individual does not consume enough fiber during treatment or surgery, the individual may have constipation and will lack the health benefits of fiber in the diet.

A: Whole foods with fiber are preferred because they contain a variety of vitamins, minerals, and phytochemicals (plant chemicals) that help your body remain healthy. Adding and regulating fiber in the diet is always the first choice. Some people may require a fiber supplement like Metamucil when it is difficult to manage the consistency of the stool with diet alone. Many fiber supplements are only soluble or insoluble fiber.

Benefiber is wheat dextrin, and FiberCon is calcium polycarbophil, and both are mainly soluble fiber. Citrucel is methylcellulose, which is mainly insoluble fibers that is nonfermentable. Metamucil contains psyllium, which is mainly soluble fiber, but also some insoluble fiber. The type of fibers (whether they are soluble or insoluble) in these supplements affect the digestive tract in much the same way as the soluble and insoluble fiber in foods.

If a fiber supplement is necessary, the individual should begin with a low dose and gradually increase the amount of fiber. It is important to ask your physician or dietitian how much fiber to add because too much fiber may decrease absorption of valuable nutrients. Fiber supplements can decrease the absorption of some other medications so I recommend the individual take other medications one hour before or two hours after consuming the fiber supplement to minimize the interaction.