Dietary fiber has proven to be very helpful in managing chronic diseases in humans. Dietary fiber lowers cholesterol and reduces the risk of heart disease. It slows intestinal sugar absorption and helps control type 2 diabetes. Fiber also promotes colon health and reduces symptoms in many intestinal and colon diseases.
And indeed fiber is used to help with symptoms of diabetes and various intestinal diseases in dogs. But how much fiber do dogs need? Can dogs be fed too much fiber? Although we don’t know the exact answer, too much fiber can interfere with normal digestion and absorption of dietary nutrients.
Types of Dietary Fiber
There are two types of dietary fiber, insoluble and soluble. Fiber is found in most plant sources of food. Soluble fiber attracts water and slows the movement of intestinal contents. It also slows the digestion and absorption of some nutrients like sugar, starch and cholesterol. That is why it aids in the management of human diabetes and heart disease. Insoluble, or indigestible, fiber increases stool volume and speeds material through the intestines.
Most plant-based foods contain both types of fiber, with different foods containing different amounts of each type. Oats, beans, peas, barley and the meat of apples and fruits contain larger quantities of soluble fiber. The skins of fruits and vegetables, whole-wheat, wheat bran, nuts, beans, cauliflower, green beans and potatoes contain larger amounts of insoluble fiber.
Together, insoluble and soluble fiber promote intestinal and colon health. Some sources of fiber like beet pulp, cabbage, rice bran and guar gum are prebiotics. They contain sugars that promote the growth of beneficial bacteria that maintain the health of the cells lining the colon.
Too Much Fiber in the Diet
Studies suggest that large amounts of fiber in the diet can interfere with the intestinal absorption of calcium, magnesium, iron and zinc. Because it decreases the absorption of cholesterol, a fatty acid, it is also speculated that high fiber diets may interfere with the absorption of other fats.
Although current research is minimal, studies in the 1990’s reported reduced activity of pancreatic enzymes with high fiber diets. Pancreatic enzymes are necessary for intestinal protein, fat and carbohydrate digestion and absorption. Decreased function of these enzymes would impair normal intestinal function.
Increased dietary fiber consistently increases stool volume and frequency and indicate that a diet that may be too high in fiber.
Dietary Fiber Requirement for Dogs
Although there is no universal “dose” for fiber in the diet, most veterinary nutritionists recommend 2-5% of the dry matter (after moisture has been subtracted) of the diet. Although higher levels of fiber are necessary to control some medical conditions, maximum levels of dietary fiber should be less than 10% with 7% a more preferable maximum. Most commercial dog foods meet these requirements. However, grain-free diets often exceed 10% fiber due to their reliance on beans and other legumes and fiber rich carbohydrates.
Dr. Ken Tudor,
THE DOG DIETITIAN