The company which makes 6-Oxo Extreme, the supplement in question, says yes. Major League baseball disagrees.
Proviant Technologies, the maker of 6-Oxo Extreme, said in a statement reported by the Philadelphia Inquirer: "While advances in analytical testing and sensitivity in detection of metabolites have made drug testers more proficient at catching cheaters, the unintended consequence is that a perfectly legal and untainted substance can cause a positive test for a banned or illegal substance.
"Although little information has been released about the specifics of the alleged positive test, our preliminary investigation of these allegations has uncovered information showing that the main active ingredient in our product will trigger a false positive for androstenedione."
Major League Baseball executive vice president of labor relations and human resources Rob Manfred told MLB.com: "All I can say about that is that there definitely wasn't a false positive in Mr. Romero's case. We've been through the lab results with the director of the WADA [World Anti-Doping Association] lab in Montreal and she's completely confident with the report that there was a banned substance in his urine."
Romero was suspended earlier this month after losing an appeal. The winning pitcher in two of the four Phillies' wins in the World Series will miss the first 50 games of the 2009 season.
Romero has contended he isn't a drug cheat. He tested positive twice late last season. His appeal was held before the World Series, but was ultimately denied.
"I still cannot see where I did something wrong," Romero said. "There is nothing that should take away from the rings of my teammates. I didn't cheat. I tried to follow the rules."