So far on our herbal tour of Zaytuna Farm we’ve met Rosemary, Yarrow, Aloe, Mint and Sage. Today we’re stopping in at one of our more controversial herbal heroes. Allow me to introduce you to Symphytum officinale, previously known variously as knitbone, healherb, wound wort and all heal. More commonly known as Comfrey, he’s been used medicinally for aeons, but in recent years has fallen out of favour over fears of toxicity. Comfrey is a complex character, but like many herbal heroes, one that’s worth getting to know better.
To begin with there is not just one comfrey. There are more than 30 species of Comfrey. There’s your regular Symphytum officinale. There’s Russian comfrey, Symphytum x uplandicum, which is said to make the best compost and fertiliser. Isabel Shippard recommends the hybrid species Symphytum uplandicum x peregrinum, as being the most beneficial for human use, as it is free of the problematic alkaloids mentioned below. She also mentions that inaccurate labelling is an issue with comfrey being sold by nurseries and garden shops, adding to the confusion.
Comfrey is a hairy, slightly prickly fellow, quite lovely to look at but not a plant to really snuggle up to. It has deep roots, dark green leaves, and the entire plant is covered in short, rough hairs. Flower colour varies between species, though the hybrid recommended above is a sterile, and does not set seed. Regular picking of the leaves will encourage new growth and discourage flowering.
Comfrey growing at Zaytuna Farm.
At Zaytuna, comfrey moves around, holding up edges here and bordering bananas there, but there’s always some quietly doing it’s thing somewhere on site. At the moment it’s really loving being interplanted with mint and sweet potato under the bananas. In Zaytuna’s subtropical climate comfrey is a perennial herb but in colder climates it can die back in winter. Comfrey likes sun or partial shade and when he finds a place he likes he can really make himself at home, and can be extremely long-lived. He likes humus-rich soil, and plenty of water but doesn’t like being waterlogged.
Comfrey has thick, clumping roots which expand but do not generally run, though at least one species, Creeping Comfrey, will do just that. Comfrey can most easily be propagated by root division, with each piece of root potentially growing into a new plant.
Medicinal uses of comfrey
Comfrey contains Vitamins A, B1, B2, B3, B5, B6, B9, B12, C and E, as well as boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, phosphorous, potassium, selenium, sodium and zinc. As comfrey has deep roots, in can draw up minerals that other plants can’t reach, this in turn can benefit plants growing nearby. It’s also used to enrich soils, as a mulch or liquid tea. In a compost pile, it’s considered an activator, similar to manure, in that it will help speed up the process. As a mulch, it’s especially beneficial for potatoes, strawberries and tomatoes, but also useful for fruit trees and other crops as well.
Comfrey was a traditional nutritive boost for wellness and many people attest to their mothers and grandmothers using it during childhood illnesses. As the leaves are hairy and rough, they are often used finely sliced in salads, cooked in soups, or blended into juices. Although it is illegal for medicinal use it can still be sold and eaten as food.
Comfrey’s use internally is controversial due to the presence of pyrrolizidine alkaloids (PA). In Australia, it’s prohibited for internal therapeutic use by government legislation, as a result of concerns over the possible effects of PAs building up over time, and potentially causing liver damage. There is not a lot of research on comfrey itself and the prohibition appears to be precautionary rather than as a result of proven effects.
Research shows that PA levels in comfrey vary with growth stage and harvest time, with older leaves possessing less than younger. There are some known cases of PA poisoning due to contamination of food with seeds of other plants (not comfrey) much higher in PAs. Shippard also points out that dried comfrey has lower levels of PAs than fresh.
Many herbalists still recommend comfrey internally, and there’s a lot of anecdotal evidence on the benefits of this. Shippard’s book lists numerous cases of people including small amounts of comfrey leaves in their food or drinks for medicinal purposes and benefiting from it. Buhner recommends comfrey root powder as part of a treatment for ulcerated stomachs. Caution is recommended for internal use specifically by pregnant or breastfeeding women, by people with cancers or tumours or a history of liver problems.
Comfrey is more widely used and has long been the go-to-guy for herbalists treating sprains, bruises, ulcers, rheumatism, muscular pain and skin conditions. It is often used in compresses, poultices and salves for many of these purposes. An infused oil is a common base for salves and comfrey leaf treatments. PA intake is not considered an issue when applied externally due to its low absorption through the skin.
Comfrey is a staple in many herbalists’ and permaculturists’ gardens, and I’ve only scratched the surface of how it’s used. It’s careful use is much older than the government rulings on it, so I’d love to hear from readers who’ve had close encounters of the comfrey kind. What was your experience? Have you got any comfrey stories to share?
The Modern Herbal Dispensatory, by Thomas Easley and Steven Horne
How Can I Use Herbs in My Daily Life?, By Isabel Shippard
Herbal Antibiotics, by Stephen Harrod Buhner
Herbal Remedies, by Nicola Peterson