Thujone, is it safe?


Thujone is a known poison and the FDA (food and drug adminstration in the U.S) have restricted it’s use, but is this an overreaction?

Tansy, mugwort, wormwood and yarrow have all been used in food and drink for centuries can they really be that poisonous?  As with most science the answer is not black and white, but shades in between. Whether or not you decide to use food containing thujone is entirely your choice, but being armed with a little more information might help you make up your mind.

I spoke to Khaled M. Abass, Phd a European Registered Toxicologist from the Research Unit of Biomedicine, University of Oulu, Finland. Who told me that the, “Committee of Herbal Medicinal Products gives two different maximum daily intakes, 3 and 5 mg of thujone/person (70 kg). However, Occurrences of alpha- and beta-thujone in plants depend on plants, batch, seasons, and origins”.  This makes it rather difficult to judge how much is a safe level to use when foraging for any plant that contains thujone.  So, I asked him what he thought about collecting and eating or drinking wild plants that contain thujone and more specifically in tansy and he said , “It is difficult to estimate thujone in tansy or other mixture unless the content of thujone is shown in batch”.  Which isn’t really much help for the forager.

Needless to say there have been some animal studies that might help us come up with an anwser especially as one of them states that humans have, “claimed to be at least as sensitive as experimental animals to the central nervous system (CNS) effects of thujone”.  I’m not really sure how many rats and mice were asked, but lets just have a bit of faith in the scientific approach. One study gave stupidly high measured brain concentrations (Hold et al, 2000) and within a few minutes almost all of the animals tested died. I’m never sure about the validity of these studies, they seem a bit pointless really you could go as far as saying feeding mice water can kill them as we got a 200g mouse and gave it one cubic tonne of water. It blew up. It tells us nothing.

Luckily, that wasn’t the only study. Another (Margaria, 1963) gave  four groups of 10 female and 10 male rats various doses (0mg, 5mg, 10mg and 20mg) of thujone, (per kg of weight), six times a week for fourteen weeks. There was no observable effect reported in the 10mg does for males and 5mg for females. At the highest does there were convulsions in nine females and six males and in the 10mg group only one female convulsed and this was in day 38.  Further, there were three deaths in the female rats and one male death.  The take home from both studies is moderation. But again it is hard to know what this moderate level should be.

Thujone a poison that is in sage, wormwood mugwort and tansy

What is needed in the name of science is to turn to some anecdotal evidence as seen on a TV program.

What is needed in the name of science is to turn to some anecdotal evidence as seen on a TV program.

A few years ago Sue Perkins (Bake Off) and Giles Coren (Journalist and TV presenter) starred in a series of shows called Supersizers go… and they, for a few days, ate only food from different periods of time. In the Restoration episode Sue ate most of the tansy pudding (and according to industry gossip she was fed more off screen). That evening she complained that she “awoke feeling sick, hot and cold, intensely paranoid, a bit dark and sad”.  I tweeted her for more information and she stated that she felt very woosy and a bit trippy. Conclusive evidence indeed that tansy (and therfore thujone), does cause some sort of psychotropic response.

Indeed, to spin this out even further a bloke I met a food festival once told me that he makes a sage tincture with vodka and sage leaves and drinks copious amounts of an evening. The effects are better than acid, he states. This I think is on the other end of the scale and would certainly warn people wishing to copy his gung-ho antics to really take it very steady.

Remember the rat study, deaths can occur if you get the dose wrong! According to WebMd tansy is unsafe and they cite that, “deaths have occurred from people using tansy tea”. On the surface it would seem that the risks outweigh the benefits in using tansy. But tansy doesn’t have as high levels of thujone as common sage or even wormwood. Yet I have never seen any report to suggest that Paxo should be banned.  The trouble with force feeding a TV presenter with high levels of something that could be toxic or citing that deaths have occurred is that it doesn’t put tansy use into any context.

Many foragers I have spoken to about thujone have stated that they have not reported any problems with either eating or imbibing high levels. The most I think I’ve personally drank is around 6-10 pints of yarrow beer in a night, or a bottle of homemade vermouth. I did not feel any convulsions nor did I die.  Top Irish chef Darina Allen advocates it’s use and having met her at a food festival I found that she was a very pleasant and charming women and one would assume that she didn’t secretly want to kill everyone. It would also suggest that tansy is fairly widely eaten, at least in Ireland. On a personal note too, I’ve eaten or drank it from time to time along with wormwood rich home made vermouth, sage and onion stuffing and mugwort ale. Not at the same time and all in some moderation. I am of the personal opinion that if you do decide to try it then treat it like any other new food, eat a little see if you react then eat a bit more.

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