& Alan Titchenal Tuesday, March 2, 2010
Childhood obesity – is more fiber the answer?
Childhood obesity has become a major national health concern. With one in three children in the U.S. overweight or obese, the pressure is high to find new strategies to solve this problem on a nation-wide level. Weight management in children is certainly as complex as it is in adults, so solutions will not likely be simple. Many factors likely play a role, so we should not be looking for a single solution to prevent or reverse the problem.
Of course, there has been no shortage of overly simplistic solutions proposed. These “solutions” may be based on research, however, those with weight problems may need to have a fairly good scientific background to understand the limitations of these supposed solutions. One nutritional factor that is some times touted as a cause of weight gain is diets with inadequate dietary fiber. Presently, some research implies that increased dietary fiber can assist with weight loss in adults and this, no doubt, will be considered in the battle against childhood obesity.
Question: What is dietary fiber?
Answer: Dietary fiber is actually more than one type of food component. Broadly, fiber is present in foods in both insoluble and soluble forms. Insoluble fiber is the most obvious form in foods. Your grandmother may have called it roughage. Insoluble fiber is not broken down by the gut bacteria, so it assists the movement of food components through the entire digestive system. Insoluble fiber generally provides a natural laxative effect.
Soluble fiber is less obvious because it forms water-holding gels in the intestinal tract. It also is known as a fermentable type of fiber. This means that the colony of bacteria living in our lower intestine can break down some of the soluble fiber components into smaller units and the resulting byproducts benefit the health of the intestinal cells.
Q: Should increased fiber be recommended to prevent or treat childhood obesity?
A: We discussed this with Dr. Maria Stewart, a fiber researcher in the Human Nutrition, Food and Animal Sciences Department at the University of Hawaii Manoa campus. Dr. Stewart indicated that the use of fiber for weight loss has both potential pros and cons.
Q: What are the pros for fiber and weight loss?
A: Some types of fiber make you feel full, so you eat less calories. Fiber is not entirely calorie-free, but it provides a minor amount of calories when compared to food components like starch, protein and fat. Consequently, including good fiber sources in the diet may help to decrease total calorie intake. A third potential benefit of consuming increased fiber is its ability to speed up the movement of food through the intestine and decrease the total calories absorbed. Beans, vegetables, and oatmeal are considered to be good sources of fiber.
Q: What are the potential problems associated with increased fiber intake?
A: Too much fiber can decrease the absorption of some important nutrients. Children who are raised with extremely high fiber diets run the risk of undernutrition. In particular, fiber decreases the absorption of some essential minerals like iron and zinc. These minerals play essential roles in a wide variety of biological processes that include burning calories. Consequently, excess fiber could actually sabotage weight management in the long run if mineral status is compromised.
Joannie Dobbs, PhD, CNS and Alan Titchenal, PhD, CNS
are nutritionists in the Department of Human Nutrition, Food and Animal Sciences,
College of Tropical Agriculture and Human Resources, UH-Manoa.
Dr. Dobbs also works with the University Health Service
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