Comfrey widely used in southeast Asia. The plant was also widely used and
cultivated by Europeans, who introduced comfrey to the New World in the
17th century. It is also often grown as an ornamental garden plant.
Although comfrey was used to produce teas and infusions for hundreds of
years, the presence of more than half a dozen pyrrolizidine alkaloids in
the leaf and root pose a risk of liver toxicity to animals and people.
The root, in fact, contains up to 16 times more pyrrolizidine alkaloids
than the leaf.
