Mike Cameron, the San Diego Padres' center fielder, was suspended for the first 25 games of next season on Wednesday after testing positive a second time for a banned stimulant.
Cameron, who plans to file for free agency, said he believes he took a tainted supplement.
"The one thing I wanted to make sure was explained is, no steroids," Cameron said. "I never took nothing like that before in my life. That would be 50 games, and that would affect me a whole lot more."
Cameron issued a statement through his agent, saying doctors for the players' association helped him narrow down what triggered the positive test.
"After all of the analysis and testing, I can only conclude that a nutritional supplement I was taking was tainted," he said. "Unfortunately, the actual supplement is gone, and therefore cannot be tested. Without the actual supplement in hand, the rules are clear, and I must accept the suspension."
Major League Baseball players who initially test positive for a stimulant receive counseling. Suspensions begin only with a second positive test.
Detroit infielder Neifi Perez, who received a 25-game suspension on July 6 following his second positive test, and an 80-game suspension on Aug. 3 following his third positive test.