In recent years, many health claims have been made about dietary and supplemental fiber. However, some reports (eg, those regarding oat bran) have been controversial. A review of scientifically rigorous studies shows that fiber has some preventive or therapeutic benefits in irritable bowel syndrome, diverticulosis, colorectal cancer, diabetes, and hypercholesterolemia. However, it appears to have no direct benefit in patients with inflammatory bowel disease, gallstones, or obesity. The United States has one of the lowest per capita intakes of fiber in the world. Therefore, increasing daily fiber intake either through diet or with supplements is recommended for most Americans. Consumer interest groups should lobby for more fiber-enriched foods. The challenge for education and healthcare professionals alike is to remold the nation's interest in and understanding of dietary fiber.