Synonyms and Common names: Common comfrey, Knitbone, Boneset, consolida, consormol, consound, Blackwort, Bruisewort, gum plant, healing herb, knitback, salsify, slippery root, wallwort, Yalluc (Saxon), ass ear, nipbone, and knit-bone.
Description and Habitat: Comfrey is an erect perennial growing in most damp areas of the United Kingdom, Europe, western Asia, and the U.S.A. It is a vigorous plant with broadly lanceolate leaves up to 30cm long, which taper into a point. The leaves arise as a rosette from the ground, have a rough texture, and are covered with short stiff hairs. The rosette supports a tall, erect flowering stem up to 1.5m tall, covered with opposite leaves; and forked stalks that support one-sided bell-shaped mauve or white flowers which curve downwards.
The fruits are four greyish-brown nutlets. The rhizome is quite short and thick with black finger-thick sized branched roots. The flowering period is from May to July. And is widely grown for its horticultural and medicinal benefits.
Comfrey leaves are sometimes found as an adulteration to Foxglove leaves, which they somewhat resemble, but may be distinguished by the smaller veins not extending into the wings of the leaf-stalk, and by having on their surface isolated stiff hairs. They are also more lanceolate than Foxglove leaves. Take care the two are recognised and used accordingly, Foxglove leaves can kill.
Parts used: Root and rhizome, leaf.
Harvesting: The roots should be unearthed in the spring or autumn when the allantoin levels are highest, then washed, chopped, and dried at a moderate temperature. The leaves are harvested after flowering in early summer.
Constituents: Leaf - Mucilage, tannin, allantoin, symphytine, echinidine, Vitamin B12.
Root - Allantoin (0.6-4.7%), about 29% mucilage (polysaccharides of fructose and glucose), phytosterols, triterpenoid (isobauerenol), phenolic compounds (including caffeic, chlorogenic and lithospermic acids), tannin, asparagine, pyrrolizidine alkaloids (including symphytine, cynoglossine, consolidine), inulin, resin, gum, starch.
Actions: Leaf - Vulnerary, demulcent, antihaemorrhagic, antirheumatic, anti-inflammatory.
Root - Vulnerary, demulcent, cell proliferant, astringent, antihaemorrhagic, expectorant. Symphytum is an effective stimulant to fibroblast, chondroblast, and osteoblast activity.
Indications: Leaf - Gastric and duodenal ulcer, rheumatic pain, arthritis. Topically as a poultice or fomentation in bruises, sprains, athlete's foot, crural ulcers, and mastitis. Specifically indicated in gastric ulceration, and topically for varicose ulcers.
Root - Gastric and duodenal ulcers, haematemesis, colitis; topically for ulcers, wounds, fractures, and herniae by application of the fresh root preparation. Specifically indicated in gastric ulcer and topically for chronic varicose ulcer.
Therapeutics and Pharmacology: The impressive wound-healing properties of Symphytum are partially due to the presence of allantoin which stimulates cell proliferation, thereby accelerating wound-healing both internally and externally. In superficial wounds, this acceleration of the healing process can prevent scar formation, but one must take care when dealing with infected wounds to ensure that the infection is addressed first.
Allantoin is able to diffuse through the skin and tissues, hence its traditional use as an external application for the treatment of bone fractures. On the surface of the skin, its action is aided by the contracting 'plaster' effect of the mucilage, tannins, and resins as they dry. Comfrey is an excellent remedy in the treatment of chronic and varicose ulcers, and it has been used topically with some success in the treatment of psoriasis (allantoin promotes keratin dispersal).
Allantoin is also effective when taken internally as it absorbed directly from the gut, so it is of use in gastrointestinal disorders. In addition, Symphytum is rich in demulcent mucilage, which augments allantoin’s powerful healing action in gastric and duodenal ulcers, hiatus hernia, and ulcerative colitis. The aqueous extract of the plant increases the release of prostaglandins of the F series from the stomach wall, pointing to direct action in protecting the gastric mucosa from damage.
Comfrey's astringency, due to its tannin content, will help arrest bleeding wherever it occurs. The mucilage also ensures Comfrey's usefulness as a bulk laxative and as a soothing remedy for the lower gut, and this may, in turn, operate by reflex to account for its usefulness in excessive menstrual bleeding, haematuria, and urinary spasm.
Comfrey has been used with success in cases of bronchitis and irritable cough, where it soothes and reduces irritation whilst helping expectoration. It also has a reputed anti-cancer action.
Contraindications: Care should be taken with very deep wounds as the external application of Comfrey can lead to tissue forming over the wound before it has healed deeper down, leading to the possibility of an abscess. Excessive internal consumption of the root should be avoided because of the pyrrolizidine alkaloids, which have been linked by some research to liver cancer in rats (on the other hand, there is data to demonstrate that the whole plant actually has a protective effect against liver poisoning, disease, and tumours in experimental animals). The hepatic veno-occlusive disease has been related to Comfreys ingestion at high doses over long periods, and the effects of the alkaloids are cumulative. Topical application is safer and more effective for arthritis than internal administration. External applications need not be restricted.
Preparation and Dosage: For bruises and strains steep the leaves in boiling water and allow to cool, either bath and soak the affected part in the cooled infusion, or wrap the bruised leaf around the affected part. Can be made into an ointment, combines well with meadowsweet and calendula oil.
Additional Comments & Folklore: Dorothy Hall writes that 'Russian comfrey and garlic could together, according to natural health usage, almost halve the present ills of western civilization'. An extravagant claim perhaps, but Comfrey did indeed have a wealth of medicinal uses in bygone days. Contemporary herbalists view comfrey as an ambivalent and controversial herb that may offer therapeutic benefits but at the potential risk of liver toxicity.
Comfrey was used to treat a wide variety of ailments ranging from bronchial problems, broken bones, sprains, arthritis, gastric and varicose ulcers, severe burns, acne and other skin conditions. It was reputed to have bone and teeth building properties in children, and have value in treating 'many female disorders'. One of its folklore names is ‘knitbone’ for obvious reasons, I well remember a sprained ankle where I sat for a long evening with one foot in a bowl of knitbone and warm water!
In the past, comfrey baths were popular before marriage to repair the hymen and thus 'restore virginity'. Gerard wrote in 1597 that Comfrey should be '...given to drink against the pain of the back, gotten by violent motion as wrestling or overmuch use of women...) Really??
A plant high in protein (up to 35%), comfrey is used as an animal feed and organic manure as well as a medicine. The name knitbone derives from its useful property of healing broken bones and wounds; it has even been used by orthopaedic surgeons on complicated bone fractures. This property has been known at least since Roman times, when it was named conferva, meaning to join together. Modern science confirms that comfrey can influence the course of bone ailments. The herb contains containsallantoin, a cell proliferant that speeds up the natural replacement of body cells. Recently there has been concern that the pyrrolizidine alkaloids contained in comfrey may damage the liver; however, this has been shown only with high doses of plant extracts and not with normal therapeutic doses of the whole herb.
The fresh leaves and shoots may be cooked as a vegetable or eaten raw in a salad. One of the minerals which have been extracted from comfrey is cobalt, which it uses to produce possibly the only plant source of vitamin B12, making it a valuable dietary supplement for vegans.
For the gardener, comfrey makes excellent green compost.