Check out this graphic. The size of each bubble indicates how much research has been done on the supplement, and its position on the chart indicates how beneficial the supplement is. Supplements higher on the chart are more effective according to studies. The chart also suggests a "worth it" line. Supplements below this line are not really worth your time or money given current scientific understanding. (My apologies if this has already been posted.)

Source: http://www.informationisbeautiful.ne...l-supplements/
Interactive version: http://www.informationisbeautiful.ne...l-supplements/