This study might be promising: http://www.landmarkstudy.com/ http://www.landmarkstudy.com/ "Usage patterns, health, and nutritional status of long-term multipl

This study might be promising: http://www.landmarkstudy.com/ http://www.landmarkstudy.com/ "Usage patterns, health, and nutritional status of long-term multiple dietary supplement users: a cross-sectional study" It was conducted by researchers from the University of California (Berkeley)