Psyllium husk is a type of dietary fiber derived from the plant Plantago ovata, also known as Indian psyllium or blond psyllium. Psyllium husk is a form of soluble fiber that helps to promote regularity and has been used for centuries to treat constipation, diarrhea, and irritable bowel syndrome. It can be used as a supplement for those with certain medical conditions to help prevent or reduce the symptoms of digestive issues. It is also used in baking as an egg substitute, to add texture and moisture to baked goods.