Margaret, a dedicated Tribest customer, called our office several years ago and told us, "I know about all of them because I've tried them all... Herbal Fiberblend is the only product I've tried that gets the black stuff out without fasting." Psyllium is the main fiber source in Herbal Fiberblend, and is approximately 75% to 80% dietary fiber. Also, the herbs in Herbal Fiberblend bring you a wealth of nutrients. Fourteen herbs contain iron, 14 contain B-complex vitamins, 13 contain calcium, 13 contain vitamin C, 13 contain potassium. Combined, these herbs make Herbal Fiberblend one of the most valuable fiber products available today.