Knott played 12 games mostly on special teams and made six tackles last season as an undrafted rookie out of Iowa State. He is allowed to participate in all Eagles offseason activities and preseason games.
The league announced the suspension Friday. Knott says he uses nutritional supplements and didn't realize he used a banned substance.
"Unfortunately, I now know that supplements are not regulated and thus may contain things that are not listed on the label," Knott says.
Copyright 2014 by The Associated Press