Avocado Soybean Unsaponifiables is a natural extract combination ingredient made from avocado and soybean oils. It is mixed in a ratio of one part avocado to two parts soybean and has been used in Europe for joint health since the early 90s. Based on the research that has been done with individual components of ASU, the bulk of the evidence points towards phytosterols, a natural group of fatty substances found in all plants, as the active nutrient in ASU.