DALLAS (AP) — A world champion swimmer and former University of Texas athlete is suing a Dallas-based health company claiming that its multivitamins led to her suspension from international competition.

Madisyn Cox sued Cooper Concepts on Monday in state court. She says the vitamins caused a failed drug test and a suspension handed down by the international swimming governing body.

Last year, FINA suspended Cox after she tested positive for the stimulant trimetazidine. Cox was forced to miss several major events. Her lawsuit says Cox fought the suspension and eventually had a lab conduct testing. It found the banned substance in the Cooper vitamins she’d been taking.

The company says it was “saddened and disappointed” for Cox and “immediately removed” the vitamins from its product line last year upon learning of the issue.