Jarvis Jenkins runs through a drill during minicamp. He is not eligible to participate until Game 5. (John McDonnell/The Washington Post)

Updated, 4:38, 4:52 and 6:32 p.m.

RICHMOND — The NFL has suspended Washington Redskins defensive end Jarvis Jenkins for the first four games of the season for a violation of the league’s policy on banned performance-enhancing substances.

The league announced the suspension but did not provide details about Jenkins’s violation.

He is eligible to participate in training camp practices and preseason games. His suspension is without pay.

Jenkins took over as a starter last season after Adam Carriker’s season-ending injury. He was to remain the starter this season, with Carriker remaining sidelined after undergoing a third surgery this week for his injured quadriceps tendon.

In a written statement, Jenkins said: “When I learned that I tested positive for a substance that is banned under the NFL policy, I was shocked and confused. It’s an obscure substance that I’ve never even heard of, and I still don’t know how it got into my body. My only guess is that it came from one of the supplements I was taking around the time of the test, even though none of them listed anything banned.

“I’m very sorry for the effect of this situation on my teammates and coaches, and I also apologize to my family and all Redskins fans. I will be very, very ready to contribute as soon as I get back for Game 5.”

The suspension will cost Jenkins $167,009 of his $709,789 salary for the season.

Redskins reserve linebacker Rob Jackson also is suspended for the first four games of the season for a violation of the same policy.

The team has had at least eight players suspended over the past three seasons for violations of the league’s two drug-related policies, the substance abuse policy and the policy on banned performance-enhancing substances. That list includes left tackle Trent Williams, tight end Fred Davis, cornerback Phillip Buchanon, safety Tanard Jackson, offensive tackle Jordan Black, cornerback Cedric Griffin, Rob Jackson and Jenkins.

Tanard Jackson signed a one-year contract with the Redskins last year after he was released by the Tampa Bay Buccaneers. He did not play at all last season because he was suspended indefinitely by the NFL last summer for violating the substance abuse policy. His one-year contract rolled over into this season under league rules. He is eligible to be reinstated by the NFL in late August.

Jenkins spoke to reporters following Friday’s practice and said: “I want to apologize to my fans, my parents, the Redskins. It was surprising news, just like it is to me, to you guys. [It was an] honest mistake, you know, but the NFL has rules. The thing is, I was trying to do everything by the right rules and obviously they tell us to take supplements that have ‘NSF’ on it that’s tested by the NFL. I took recovery and pre-workout supplements. Nobody knows what’s in those supplements even though the label doesn’t say it has a banned substance on it. And they tell us we’re responsible for what’s in our body. … They tell me everything to do by the book.

“Like I said, it was just a simple mistake. I accepted my responsibilities like a man. I’m going to take the suspension. Obviously I let my team down and the defense. But I’m going to come back stronger from this.”

The league and NFL Players Association have a program, with the company NSF International, to certify supplements that don’t contain any substance banned by the sport.

Jenkins said he took an over-the-counter recovery supplement that was not certified under the program. He found out in late March, he said, about his possible violation. He said he did not recall the name of the banned substance but was told it is on the league’s list of banned substances as a possible masking agent, he said.

“The NFL, [Commissioner] Roger Goodell tells us, ‘Don’t take nothing unless it has that label on it,’ ” Jenkins said. “Even though I’ve been taking this since college, you never know what these companies are testing in these machines that you’re taking these with. Obviously something may have got mixed up. I’m not making any excuses. But it’s something that happened. I’m going to step up like a man and say I did it.

“It was just a simple mistake. I figured it was cool. I read labels and it didn’t have anything on it. I looked up on it. It’s just a simple mistake.”

Said Redskins Coach Mike Shanahan: “Any time a person has a suspension, it’s always a tough blow for your football team. Hopefully our players will learn that without the label of ‘NSF,’ you can’t take any supplement because you never know what’s going to be in the supplements. So we’ll pay the price for it. He’ll be suspended for four games and hopefully our players will learn from it.”

Shanahan said there is no common thread to the drug suspensions the Redskins have suffered since the beginning of the 2011 season. He said that team officials stress caution and compliance to their players but acknowledged that the issue perhaps has not been stressed enough.

“Every situation is a little bit different,” Shanahan said. “You deal with those situations, try to make the best of it. But it’s happened a lot throughout the National Football League and we’re trying to do our due diligence to make it right, to make it a fair playing level for all players. We’ve got some strict rules and if you don’t abide by those rules, you’re going to get penalized. Unfortunately we have emphasized it but maybe not enough. Every year, we’re trying to emphasize it better and better.”

Related: Other Redskins suspensions | Jenkins had planned to take on bigger role

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More on Jenkins’s suspension and injuries to Robinson and Carriker

John Keim talks to Pierre Garcon, and examines the number of hits Robert Griffin III takes.

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