Category: Medicines - plant based
Introduction and description
Comfrey (Symphytum officinale L.) is a perennial herb of the family Boraginaceae.
It is native to Europe, growing in damp, grassy places, and is frequently found throughout Ireland and Britain on river banks and ditches.
Its range is from Scandinavia to Spain, Siberia and Turkey. The very young leaves can be eaten and we have provided information about this, but Comfrey is generally classified as a medicinal plant.
Symphytum officinale grows to 1.2 m (4ft) by 0.6 m (2ft in) at a fast rate. It has a black, turnip-like root and large, hairy broad leaves that bear small bell-shaped flowers of various colours, typically cream or purplish, which may be striped.
It is hardy and is not frost tender. It is in flower from May to June, and the seeds ripen from Jun to July. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees.
The Comfrey family
Comfrey (also comphrey) is also the common name for plants in the genus Symphytum. As the plant is grown both commercially and ornamentally, a number of hybrids have been produced. The properties of the plant depend a great deal on which plant or hybrid is being described.
Russian comfrey Symphytum × uplandicum , for example, is a cross or hybrid of Symphytum officinale (Common Comfrey) and Symphytum asperum (Rough Comfrey). Symphytum × uplandicum is widespread in the British Isles, and interbreeds with S. officinale. Compared to S. officinale, S. × uplandicum is generally more bristly and has flowers which tend to be more blue or violet.
The "Bocking 14" cultivar of Russian Comfrey was developed during the 1950s by Lawrence D Hills, the founder of the Henry Doubleday Research Association (the organic gardening organisation named after the Quaker pioneer) following trials at Bocking, near Braintree, the original home of the organization. Bocking 14 is sterile, and therefore will not set seed (one of its advantages over other cultivars as it will not spread out of control). It is propagated from root cuttings. Despite being sterile, Bocking 14 Russian Comfrey will also steadily increase in size via its roots.
Bocking 14 has high levels of allantoin (for healing) and high levels of Potassium which makes it less palatable. A more palatable variety is Bocking 4 which has less Potassium. Bocking 4 became popular as a folk remedy in America where it was used in 'green drinks' as a tonic.
Apart from its medicinal uses, which are described below, Comfrey is an excellent green manure. The plant grows very quickly, producing a lot of bulk, but it is tolerant of being cut several times a year and can thus be used to provide 'instant compost' for crops.
A two-inch layer of comfrey leaves placed around a crop will slowly break down and release plant nutrients; it is especially useful for crops that need extra potassium, such as fruit bearers but also reported to do well for potatoes. Comfrey can be slightly wilted before application, but either way, avoid using flowering stems as these can root.
A liquid feed can also be obtained by soaking the leaves in a small amount of rain water. If you have a water barrel, this seems to work well. The leaves quickly break down to a thick black liquid. Comfrey is an excellent source of potassium, an essential plant nutrient needed for flower, seed and fruit production. Its leaves contain 2–3 times more potassium than farmyard manure. The resulting liquid is thus excellent for potassium demanding crops such as tomatoes. Incidentally, when people refer to "comfrey tea", it is this they are referring to! Depending on how much water is used the ‘tea’ may need to be diluted.
The leaves are also a very valuable addition to the compost heap. The plants are best grown in an open sunny site in a deep rich soil if they are being grown for compost material. Comfrey is both a compost activator and helps add nitrogen and heat the heap. Comfrey should not be added in quantity, it needs to be balanced with more fibrous, carbon-rich material.
Comfrey should not be harvested in its first season as it needs to become established. Any flowering stems should be removed as these will weaken the plant in its first year.
Mature comfrey plants can be harvested up to four or five times a year, as long as they are fed [see below cultivation]. Comfrey can continue growing into mid-autumn, but it is not advisable to continue taking cuttings after early autumn in order to allow the plants to build up winter reserves. After the growing season, the plant builds up energy reserves in its roots.
Comfrey make good companion crops, as they attract bees. Fruit trees thus benefit from being placed with comfrey plants.
But there is an additional reason why Comfrey are good companion plants. They are what is called a dynamic accumulator. As they are so deep rooted they are able to mine a host of nutrients from deep down in the soil and bring them up to ground level. Over time as they die down and the leaves are shed, these nutrients find their way to the surface, thus benefiting shallower rooted plants. It is worth adding, however, that soil nutrients increase in the presence of comfrey even when its leaves are not used as mulch, but just allowed to grow. In effect the nutrient mining works all the time.
Comfrey can be used to make a very useful general purpose potting mixture, it is too strong for seedlings. In a black plastic sack, alternate 7–10 cm (2.8–3.9 in) layers of two-year-old, well decayed leaf mould and chopped comfrey leaves. Add a little lime to slightly raise pH. Leave for between 2–5 months depending on the season, checking that it does not dry out or become too wet. The mixture is ready when the comfrey leaves have rotted and are no longer visible.
Comfrey is a chelating agent of soils. The blueness of the flower depends on the metals in the soil. Like Hydrangeas, they go bluer the more aluminium there is in the soil. The aluminium is sequestered in the root.
Comfrey is not that particular about soil type and is able to grow in light (sandy), medium (loamy) and even heavy (clay) soils. It can grow in semi-shade (light woodland) or no shade as long as it is not too hot, but it prefers moist soil. We have comfrey in our garden and it grows best by the side of a drainage ditch.
Plants can be invasive, often spreading freely by means of self-sown seed. If growing from seed, it can be sown in spring in situ.
The root system is very deep and difficult to eradicate, even small fragments of root left in the soil can produce new plants. This means however, that division succeeds at almost any time of the year. Simply use a spade to chop off the top 7cm of root just below the soil level. The original root will regrow and you will have a number of root tops, each of which will make a new plant. These can either be potted up or planted out straight into their permanent positions.
Some people find the hairs on the leaf and stem of the plant to be an irritant, so in this case it is best to wear gloves if handling the plant.
Comfrey benefits from the addition of animal manure, and can also be mulched with other nitrogen rich materials such as lawn clippings.
It is “one of the few plants that will tolerate the application of fresh urine diluted 50:50 with water”, [!] although the writer of this added “it should not be regularly added as it may increase salt levels in the soil and have adverse effects on worms”.
Comfrey is generally trouble free once established, although weaker or stressed plants can suffer from comfrey rust or mildew. Another reason to feed them well. Rust and mildew are fungal diseases, although they rarely seriously reduce plant growth and thus do not generally require control. Infected plants should not be used for propagation purposes.
If one is going to eat the plant you use the young leaves.
How palatable the leaf is, depends on the variety. Thus you will get some people saying it is exceptionally tasty and others saying it has “an unpleasant mucilaginous texture and not pleasant eating for most tastes”. This is because one person has eaten one hybrid and maybe another has eaten another, or perhaps not eaten a hybrid at all.
Plants for a future
Comfrey contains small quantities of a toxic alkaloid which can have a cumulative effect upon the liver. Largest concentrations are found in the roots, leaves contain higher quantities of the alkaloid as they grow older and young leaves contain almost none. Most people would have to consume very large quantities of the plant in order to do any harm, though anyone with liver problems should obviously be more cautious. In general, the health-promoting properties of the plant probably far outweigh any possible disbenefits, especially if only the younger leaves are used.
Dr Duke’s analysis of Comfrey has a very detailed analysis of the root, which indeed contains a number of toxic chemicals, but only a little information on the leaf. From the analysis of the root provided by Dr Duke, despite the fact it is actually full of minerals, one would be extremely unwise to eat the root.
One of the really beneficial chemicals in the leaf is Rosmarinic acid, a chemical also found in the herb Rosemary. Amongst other things, this chemical is a blood thinner, antibacterial, an antidepressant, and an antiviral able to combat herpes, and HIV. It is also a pain reliever.
Allantoin, also in the leaf, appears to help with indigestion, as it is Antipeptic [30-130 mg/man/day]. It is also Antiulcer and an Immunostimulant.
In Spain, Comfrey is treated as a delicacy, but they know their plants. Only the young leaves are used and the hairs are cleaned off. The leaves are then simply boiled and used like spinach. In Aragon, it “is a real delicatessen" [sic]. Another equally popular form of preparation again uses the young leaves cleaned of their hairs, but this time fried in a sort of batter, not unlike tempura batter. According to one who has tried it, the taste is “outstanding, especially with a slice of Dutch or Cheddar cheese”.
A stated above, you would not consume the root. But this is not a reason to discard the root as non beneficial medicinally. Many of the chemicals in the root are potentially very useful, but one would have to know how to extract them and separate them from the ones that are toxic.
The Cafffeic acid in the root, for example, is a very potent antiviral agent able to handle HIV, the adenovirus, the flu virus and the vaccinia virus.
Chlorogenic acid, again in the root, has extra antiviral activity being able to deal with EBV, Herpes, HIV, polio, it is also an Antibacterial. Depending on the cause of the tumour, and via the antiviral and antibacterial activity, Chlorogenic acid also has Antitumor activity - Antitumor (Colon); Antitumor (Forestomach); Antitumor (Liver); and Antitumor (Skin). If the tumour was caused by a metal this same chemical may also help as it is a Metal-Chelator.
Glucuronic-Acid in the root is an antidote to both Camphor and Morphine and described as a “Detoxicant”.
On the other hand the last thing you would want to consume are the chemicals Consolicine and Consolidine in the root, which together are CNS-Paralytic; Curaroid; and Myoparalytic. Nor would it be a good idea to consume the Echimidine in the root which is Hepatotoxic and Mutagenic; or the Lasiocarpine and Lycopsamine which are Carcinogenic and Hepatotoxic.
The plant clearly wishes to protect its root. We should respect its wishes.
Comfrey leaves were once used as a sort of poultice or balm to heal wounds. Allantoin, available in the leaf of some varieties in quite high quantities is, according to Dr Duke’s analysis, a very helpful chemical if you have skin complaints or wounds as it is
Antidandruff; Antiinflammatory; Antipsoriac 2%; Antiradicular [pain relief]; Keratolytic [A keratolytic agent is a skin peeling agent] ; a Sunscreen 0.1%; Suppurative [which in this context means an agent that can draw the pus from wounds or boils etc] and a Vulnerary [a medicine used in the healing of wounds]
Symphytum officinale was the principal ingredient in a balsam formula, used in humans and animals, "invented by the great Veterinary Dr Segimón Malats”, who created the first Vet University College in Madrid, sixth in the world, in 1772. It was advertised as “Bàlsam de Malats. Bàlsam contra les ferides, ideat per Segimon Malats i Codina, d’eficaç acció hemostàtica I cicatritzant, molt utilitzat pel tractament de les ferides durant tot el segle XIX i a principis del XX”.
This wound healing ability was once reflected in its common names – knitbone and boneset - and the derivation of its Latin name Symphytum, from the Greek symphis, meaning growing together of bones, and phyton, a plant.
Comfrey was historically used to treat a wide variety of ailments ranging from broken bones, sprains, arthritis, gastric and varicose ulcers, severe burns, acne, cuts, bruises, sores, eczema, varicose veins and other skin conditions – all of which seem to be supported one way or another by Dr Duke’s analysis.
Plants for a future
External applications and internally taken teas or tinctures of the leaves are considered to be completely safe, but internal applications of tablets or capsules are felt to have too many drawbacks for safe usage.
A homeopathic remedy is made from the fresh root, harvested before the plant flowers. This has a very limited range of application, but is of great benefit in the treatment of broken bones and eye injuries. The German Commission E Monographs, a therapeutic guide to herbal medicine, approve Symphytum officinale for blunt injuries .
In 2001, the United States Food and Drug Administration issued a ban of comfrey tablets and capsules marketed for internal use, and a warning label for those products intended for external use.
- Culpepper's Complete Herbal on Comfrey 016805
- Dr Duke's list of aluminium chelating plants 017803
- Dr Duke's list of Chemicals and their Biological Activities in: Symphytum officinale L. (Boraginaceae) -- Comfrey 018925
- Dr Duke's list of Chemicals, Biological Activities and References in: Symphytum officinale L. (Boraginaceae) -- Comfrey 018926
- Dr Duke's list of Plants containing SELENIUM 020550
- Dr Duke's list of Plants with Antilupus activity 018440
- Dr Duke's list of Plants with Antipapillomic Activity of high potency 018898
- Dr Duke's list of Plants with Antitinnitic activity 018434
- Dr Duke's list of Plants with Vulnerary activity 018927
- Medicinal plants used for musculoskeletal disorders in Navarra and their pharmacological validation 016093
- Mrs Grieve on Comfrey 016795
- Philippine Herbs Used in Small Animal Practice 021374