Isoflavone bioavailability from foods and supplements dietary factors impacting utilization

Isoflavones comprise a group of phytoestrogenic polyphenols with antioxidant properties occurring especially in plants of the Leguminosae family, and are consumed by humans mostly in form of soy (Glycine max (L.) Merr.) and products. Soy rich isoflavone products have been promoted recently as foods or supplements with functional or nutraceutical characteristics, especially for the prevention of osteoporosis, for improved cardio-vascular function, and against prostate and breast cancer. However, there is controversial discussion on the bioavailability of isoflavones, a prerequisite for their action in the human body, depending potentially on the type of isoflavonoid, its chemical binding state (aglycon vs. glucosides), and the food matrix, such as the presence of dietary fibre. In addition, dosing and factors altering gut microflora, such as prebiotics, have been suggested to affect utilization of isoflavones. KEYWoRdS: isoflavonoids, health, supplements, food matrix, bioavailability. Torsten Bohn