A U.S. Army Special Forces (SF) unit was studied to determine characteristics of supplement users, assess nutrition knowledge, and identify nutrition information sources. SF-qualified (n = 119) and non-SF, support soldiers (n = 38) participated. Most soldiers (87%) reported current supplement use with more SF (90%) than non-SF, support soldiers (76%) using supplements (p < or = 0.05). Supplements SF reported using most were multivitamins, sports bars/drinks, and vitamin C. The mean nutrition knowledge score for all soldiers was 48.5 +/- 15.2% correct responses. Most soldiers incorrectly believe protein is used for energy for short-term athletic events (64%) and that vitamins provide energy (58%). The most common information sources reportedly used were popular magazines/books (75%), friends/teammates (55%), physicians/nurses, radio/television (34%), and the Internet (31%).