The Pentagon is warning members of the military services to avoid consuming poppy seeds, which can cause positive drug test results for opiates.

The poppy plant is the source of opium and such derived products as heroin and the medical drugs codeine and morphine, though the seeds naturally contain only trace amounts of opium and cannot produce a “high.”

However, production and harvesting can, even with the best intentions, contaminate the seeds with the plant’s opium-yielding chemicals and thus register similarly on drug tests for up to 48 hours after consumption, according to the U.S. Anti-Doping Agency.

The Department of Defense testing regime differentiates between the presence of codeine or morphine from seeds and the same presence from drug use.

The Pentagon is now cautioning though that new data showed that certain varieties of seeds may be being contaminated with higher levels of codeine during harvesting and processing than thought.

To avoid false positives from seeds undermining the military’s efforts to prevent illicit drug use, U.S. Undersecretary of Defense for Personnel and Readiness Gilbert Cisneros Jr. warned military personnel to avoid consuming poppy seeds and associated products such as some popular bagels or cakes in a memo last week.

Civilians have previously run afoul of drug tests due to eating poppy seeds, including a pair of New York mothers tested in the hospital while giving birth.

The premise of poppy seeds leading to a positive drug test also came up in a 1996 episode of the TV comedy “Seinfeld,” wherein poppy seeds caused a positive drug test that prevented Elaine from going to Africa.

• Brad Matthews can be reached at bmatthews@washingtontimes.com.