This is an excerpt from Athlete's Guide to Sports Supplements, The by Kimberly Mueller & Josh Hingst.
A-to-Z Supplement Guide
The supplement entries use the symbols listed in the following table to easily identify the supplements that have been proven to be beneficial or possibly beneficial for the corresponding performance variables. If a supplement has been proven to be beneficial for a particular performance variable, the supplement entry is marked with a black symbol; if the research shows that a supplement is possibly beneficial, the entry is marked with a gray version of the corresponding symbol.
Learn more about The Athlete's Guide to Sports Supplements.