Fiber and Children's Diets

Children older than 2 years should gradually adopt the American Heart Association Eating Plan. That means saturated fat intake should be 8–10 percent of total calories and dietary cholesterol should be limited to no more than 300 mg daily. Children should also get the majority of calories from complex carbohydrates high in fiber.

A fiber guideline of "age plus 5" has been proposed to set dietary fiber amounts for young children. This means, for example, a 5-year-old should consume 5+5=10 grams of fiber per day. Once a child's caloric intake approaches that of an adult (1500 calories or more), 25 total grams should be well tolerated.
http://www.americanheart.org/presenter.jhtml?identifier=4608
High Fiber Health