Our local baker makes a very good wholemeal loaf which he garnishes liberally with poppy seeds. As I tucked in to a sandwich made from this excellent bread, I spared a thought for the governor of London’s Brixton Prison who recently suffered the exquisite embarrassment of failing a drugs test. Routine heroin tests for several inmates at the Prison had come up positive but the prisoners protested their innocence and challenged the governor to take a test himself. Generously he did and that’s when the embarrassment occurred. Eventually, the source of the “drugs” was traced to bread laced with poppy seeds. The seeds contain morphine and other opiates which register as positive in the prison-drugs test and although this story sounds like an urban myth, poppy seeds are now banned from the prison.
Poppy seeds are used in many cultures as a food ingredient, for example to garnish breads and rolls, as an ingredient in cakes or ground in sauces and pastry fillings. The seeds are harvested from the dried seed capsule of the opium poppy (Papaver somniferum). The opium poppy is well known as the source of the powerful painkillers and drugs of abuse, morphine and codeine (opiates). Although the seeds themselves contain only trace amounts of the opiates, they can be contaminated by poor harvesting practices or insect damage so that commercially available poppy seeds contain varying amounts of morphine.
But does it matter that poppy seeds contain opiates? The EU clearly thinks it does matter because in 2011 it commissioned a huge report on the public health risks of consuming opiates in poppy seeds. Consumption of the seeds in food varies considerably across the EU but some Central-Eastern European cultures use poppy seeds widely. The report contains a mass of data and found that, although some groups may be consuming morphine at active levels from poppy seeds, few side effects are reported. One person did, however, report morphine-like side effects after consuming a meal sprinkled with a massive 75g of contaminated poppy seeds.
Poppy seed-opiates also matter to people undergoing drug testing and there are numerous reports of failed workplace heroin tests, and lost jobs, after consumption of food containing poppy seeds. It may seem surprising but consumption of just one poppy seed bagel can lead to urinary morphine levels of 250ng/ml after three hours. Workplace heroin testing actually assesses morphine levels so that it can be difficult to distinguish between consumption of heroin (heroin is broken down to morphine) and of poppy seeds. To try to eliminate the poppy seed-false positives, the threshold for a positive test was raised from 300 ng morphine/ml to 2000 ng/ml in US Federal Workplaces in 1998. Not all employers follow this rule so that confusion can still arise. For similar reasons, US Federal Prisons forbid prisoners to eat foods containing poppy seeds and athletes undergoing routine drug testing are advised to avoid foods containing the seeds.
A better solution would be to find a heroin-specific test. Forensic scientists identified 6-monoacetylmorphine (6-MAM) as a heroin-specific metabolite found in the urine of heroin users and absent after poppy seed ingestion. In principle, this should deal with the confusion but 6-MAM is broken down fairly quickly in the body so that it can be missed. Very recently a team from King’s College, London have reported another heroin-specific metabolite, ATM4G, that they hope might provide the basis of a better test.
Some people have taken advantage of the presence of opiates in poppy seeds by steeping the seeds in water to release the active compounds. We could call this a poppy seed tea, and it should in principle produce low level opiate effects. The problem with these brews is that because the levels of morphine in the seeds are very variable so the potencies of the teas also vary in a largely unpredictable manner. Great care should be taken and there are more than a dozen reports of deaths occurring after consuming poppy seed tea owing to morphine overdose.
The poppy seed-opiate story also exposes an interesting conundrum. If someone takes morphine or even uses poppy seed tea we would call them a drug user. If another person eats poppy seeds, we would say that it’s part of their culture, even if they experience low-level morphine effects. All I know is that I shan’t stop buying my baker’s bread or his lemon and poppy seed cake!