The average American diet simply does not have enough fiber. White enriched flour has almost no fiber content. The most popular veggies are tomatoes, iceberg lettuce, and cucumbers, which have almost no fiber content (or vitamin content for that matter). Fiber helps regulate the digestive system (especially soluble fiber) by moving lipids (i.e. fats) through the blood stream and helping regulate sugar absorption. Insoluble fiber helps move bulk through the intestines, easing constipation and maintaining healthy acid levels.