Ninkovich, 32, was surprised at the news and accepted responsibility for it.
“Few things are more important to me than my name and reputation. This might call that into question for some, which has me heartbroken," Ninkovich told ESPN. "I don't want to cut any corners. I want to do things the right way, with high integrity, and that's what I have always wanted to stand for.”
“Any supplement I've ever used was bought at a store. I was unaware something I bought had a substance in it that would give me a positive test because it wasn't listed [as an ingredient],” he added. “One thing I have learned is that if a supplement is not NSF certified there are no regulations that ensure that what is on the label is 100 percent accurate. That is a hard lesson for me to learn at this stage in my career, but I take responsibility for it. It's a mistake I made and it hurts that I won't be there for my teammates.”
Ninkovich has played in 116 consecutive games since joining the Patriots in 2009. He was dealing with a torn triceps injury suffered in preseason and was likely to have missed the start of the season anyway.