ABSTRACT
Most guidelines recommend a high-fiber diet of at least 25-30 g/day for patients with constipation or 14 g per 1,000 kcal/day. The average American ingests only 15 g/day of dietary fiber. A systematic review evaluating the effects of dietary fiber from cereals, fruits, and vegetables in healthy individuals demonstrated that cereal and vegetable fiber resulted in similarly increased fecal weight, which was higher than that from fruit fiber. This study also showed that in healthy individuals with a slower whole gut transit time of =48 hours, each gram of increased dietary fiber reduced the transit time by 30 minutes, regardless of the food fiber type. Despite heterogeneity among available data, soluble fiber, especially psyllium, has been shown to be effective in chronic constipation. There are not enough data on non-psyllium soluble fiber, insoluble fiber, and synthetic fiber to support recommending them for chronic constipation.
