OptiFiber® Lean features Shimizu Propol® A propolmannan. Propol A is a highly pure, natural soluble fiber created from Amorphophallus konjac–derived glucomannan using proprietary processing technology. This fiber has been studied for its viscosity and stability through the digestive tract, and studies support its health effects, including satiety, weight control, glucose and lipid metabolism, and bowel regularity.*