OPUS (Osteoporosis Prevention Using Soy) is the first multi-site, long-term research study on the use of soy isoflavone supplements to prevent bone loss in postmenopausal women.

Conducted by researchers at six university-related healthcare centers and funded by a grant from the USDA's Cooperative State Research, Education and Extension Service (CSREES) , the OPUS project is dedicated to conducting research studies and developing educational materials that help women and their primary-care physicians make informed decisions regarding the use of soy-based dietary supplements to prevent osteoporosis.