As a result of these negative findings some researchers and doctors have begun to question the idea that insoluble fiber protects against colon cancer, a concept that had arisen from a large body of older research. Fiber also fills the stomach, reducing appetite. In theory, fiber should therefore reduce eating, leading to weight loss . However, at least some research has found increased fiber to have no effect on body weight despite decreasing appetite. 14 Lignan, a fiber-like substance, has mild antiestrogenic activity.
Whole grains are particularly high in insoluble fiber.
Most people are fiber deficient. Many so-called whole wheat products contain mostly white flour. Junk food is also fiber depleted. The diseases listed above are more likely to occur with low-fiber diets. Western diets generally provide approximately 10 grams of fiber per day.