(CNN) -- The US Defense Department issued an official warning to troops last week: If you don't want to test positive on a drug test, you should avoid poppy seeds.
A memo distributed on Friday from Gilbert Cisneros, the under secretary of Defense for personnel and readiness, directed military service leaders to "notify service members to avoid consumption of all poppy seeds to include food products and baked goods containing poppy seeds."
"Out of an abundance of caution, I find protecting service members and the integrity of the drug testing program requires a warning to avoid poppy seeds," Cisneros wrote in the memo, released on Tuesday. "As more information becomes available, we will revise this policy accordingly."
The concerns over poppy seeds resulting in positive drug tests are not new, as Cisneros pointed out in his memo. Indeed, a 1998 study said drug screen cut-offs had been questioned because of the positive results "following the ingestion of poppy seed containing food products."
That has persisted over the years. Another study published just last year says consuming poppy seed products can lead to "opiate-positive urine drug test results."
However, Cisneros said that recent data suggests some poppy seed variants have higher codeine contamination than previously thought.
"Consumption of poppy seed products could cause a codeine positive urinalysis result and undermine the Department's ability to identify illicit drug use," Cisneros wrote.
The contamination could pose a problem for service members with a proclivity for poppy seed bagels or muffins who can be drug tested at random by their unit.
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