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Coltsfoot toxicity.

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"Coltsfoot" includes both Tussilago and the various species of Petasites.

They've been used as cough herbs. And both Petasites spp. and Tussilago farfara contain livertoxic PAs.

Trouble with livertoxic PAs is, they're insidious: you cannot detect their effects unless you do a liver biopsy (on live people) or a liver autopsy (after they died). Which is why people insist that "comfrey (Symphytum spp.) is perfectly safe - I've been eating it for years!" - oo-kay. So when was your last liver biopsy then? Any signs of VOD (veno-occlusive liver disease), the surefire sign of PA poisoning, and a disease that will slowly but surely do your liver in?

The livertoxic PAs are catalysts: a very tiny amount of livertoxic PAs will destroy a very large number of liver cells. Much like freons taking out the ozone layer.

It's a cumulative poisoning; eat coltsfoot, or comfrey, or Senecio, or one of the other plants which contain livertoxic PAs regularly or even irregularly, and watch the progress of VOD in your liver. You can't get VOD any other way, and if you do let it progress it means either a liver transplant or death, in the long run.

Of course we all die one day, but oh the irony, to die of a herb you use to stay healthy.

It's the "Well, aunty was poorly, may she rest in peace." -thing. So you didn't have a liver autopsy done, then? Of course you didn't - any fool could see that she wasn't well.

A hidden disease. Insidious.

I don't use any plants that contain livertoxic PAs.

Note, there's nontoxic PAs as well, so don't paint all plants that contain PAs with the same brush; but do avoid the ones with livertoxic PAs.

For safe cough herbs have a look at iceland moss, elecampane (there's a cool root!), mullein, plantago, horehound, thyme, hyssop, licorice ... there's lots.

Pretty much all of the Asteraceae (daisy family) and Boraginaceae (borage family) contain pyrrolizidine alkaloids. What you want to know is if they're toxic PAs.

They're toxic in most species of comfrey (Boraginaceae), and in the coltsfoots (be they Petasites or Tussilago) (Asteraceae).
They're nontoxic in the Echinaceas (Asteraceae).
And as far as I know, they're not toxic in boneset (Eupatorium perfoliatum), gravelroot (Eupatorium purpureum), or Joe Pye weed (Eupatorium maculatum) (Asteraceae).
Again as far as I know, they're toxic in the Ageratinas, which used to be Eupatoriums (Asteraceae).

And so on.

More about the livertoxicity of some PA -containing plants here and here.

There are rumors that pyrrolizidine alkaloids could be destroyed by heat. I haven't heard anything definitive, and a lot of other alkaloids aren't destroyed by heat. The xanthine alkaloids, for instance: caffeine, theine, theobromine. And nicotine, from tobacco. Among others. So can you heat the coltsfoots and hope that they're then nontoxic? I have no clue, and no lab to test this with. I just avoid the coltsfoots.

Related entries: Livertoxic PAs - Coltsfoots in flower - Comfrey again


...wonder if anyone could talk susun weed into donating her liver for autopsy? that might settle the endless debate...

(post mortem, of course)

A liver biopsy would do the trick, too, pre-mortem.

i'd been taught by the "oh it's been used for eons, what does science know?" school of thought, which didn't sit well, so i'm glad to see some more solid proof about what science DOES know.

the more important question is though, is the damage done from PAs you've already ingested reversible? and if so, is it the normal be-kind-to-your-liver kind of reversible, or some antidote-required kind of reverisble?

The liver can repair itself, if enough healthy tissue is left, given time to do so.

And the Germans, who are more or less sane about livertoxic PAs, say you should do at most a few weeks a year of the less toxic ones, and to avoid the more toxic ones altogether.

I expect that the damage is reversible, provided you steer clear of livertoxic PAs for long enough.

in researching further, i found this link, which references the roeder text. he lists (i think it's a he, but actually i don't have any proof) lungwort, boneset, and joe pye weed as well, though he does note that lungwort is of "questionable" PA content [whereas roeder listed it as safe]. it's a nice article. he also lists some plants that we don't use medicinally but which are animal fodder or which grow as weeds that contaminate food supplies, which is not useless information...
further, he's got descriptions of the symptoms, and of reported poisoning incidents, which was very interesting.

Nice article, thanks. Prof. Röder has sent me two PA articles in addition to the one I have online; one of these months I'll get around to asking him if I can put those online, too.

Where do you get your information. I see your statements but you do not sight your references. Who did the tests to determen Coltsfoot has the toxic PAs you speak of?

That's CITE references, not sight. Pet peeve...
Try the PA paper I have online for references. The livertoxicity of PAs in coltsfoot (both Petasites and Tussilago) has been known for at least 20 years.

I there quite a while since I left a comment, but I do make coltsfoot wine. Apart from the alcoholic affect to the liver what about the flowers.

They contain livertoxic pyrrolizidine alkaloids - I'd stop making that, especially if you're talking Petasites, not Tussilago.

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