According to the Huffington Post, an investigative documentary by Al Jazeera alleges that Phillies first baseman Ryan Howard and other prominent professional athletes received human growth hormones from a Texas-based pharmacist. The Huffington Post viewed the documentary, The Dark Side, before it was scheduled to be aired Sunday night.

Howard, 36, denied to Al Jazeera that he used the drug. He was alleged to have received performance enhancers from Charlie Sly, a pharmacist who once worked at an antiaging clinic in Indiana. Sly claims in the documentary to have supplied human growth hormones to Howard, Peyton Manning, Mike Tyson, Washington Nationals infielder Ryan Zimmerman, and others.

Manning's agent denied the claims to Al Jazeera, calling them "outrageous and wrong." Zimmerman also denied the report.

The Huffington Post report says the documentary's credibility "hinges largely on whether Sly should be believed, or whether he's simply concocting stories to impress Liam Collins." Collins, a British hurdler, went undercover in an attempt to expose the widespread use of performance enhancing drugs. Sly's claims were recorded by the network without his knowledge. Collins met with Sly under the guise that he was trying to qualify for the Olympic Games this summer.

Sly posted a video to YouTube on Saturday night saying that Collins was a "recruited fraudster."

"The statements on any recordings or communications that Al Jazeera plans to air are absolutely false," Sly said. "To be clear, I am recanting any such statements and there is no truth to any statement of mine that Al Jazeera plans to air."