Q. Is it possible to eat too much fiber?
A. Too much fiber in the diet can do more harm than good. Symptoms ranging from painful gas, nausea, and vomiting to an inability to absorb essential vitamins and minerals are possible results of a sudden switch to a diet very high in fiber. People with sensitive digestive tracts can be especially affected by too much fiber, and even normal digestion needs a period of adjustment to less refined foods.
Experts remind us that not all forms of fiber are the same. Bran, the outer cover of a grain kernel, is mostlycellulose, and is sometimes an effective treatment for constipation. However, eating bran dry can have the opposite of the desired effect and may instead help to clog the intestine.
High-fiber breads are relatively new on the market and contain many times more fiber and about 30 percent fewer calories than most white breads. High-fiber breads contain wood cellulose, as well as wheat bran and other types of fiber. While these products may be more filling and less “fattening” than other breads, wood-pulp fiber is not the same as the dietary fiber in bran, grains, fruits, and vegetables-foods considered the best sources of dietary fiber.
Nutrition scientists worry about the adverse effects on the health of people who fill up on foods containing large amounts of wood cellulose and therefore cut back on their consumption of more nutritious foods.