Comfrey Root & Leaves

Comfrey Root & Leaves (Symphytum officinale)

You will find Comfrey in Mother Gaia’s Bone Healing Powder.

Other Names: Ass Ear, Black Root, Blackwort, Bruisewort, Common Comfrey, Consolidae Radix, Consound, Consoude, Consoude Officinale, Consuelda, Grande Consoude, Gum Plant, Healing Herb, Herbe aux Charpentiers, Herbe à la Coupure, Knitback, Knitbone, Langue-de-Vache, Oreille d’Âne, Salsify, Slippery Root, Symphytum officinale,

OVERVIEW – Comfrey is a shrub that grows in parts of Europe, Asia, and North America. It can grow up to 5 feet tall. It produces clusters of purple, blue, and white flowers, and it’s famous for its long, slender leaves and black-skinned roots. The root and leaves of the comfrey plant have been used in traditional medicine in many parts of the world. In Japan, the plant has been harvested and used as a traditional treatment for over 2,000 years. Europeans have also used comfrey to treat inflammatory conditions, such as arthritis and gout. Some traditional healers have also used it to treat diarrhea and other stomach ailments.

Comfrey leaf has been used since Roman times, dating back thousands of years. This herb has been utilized in folk medicine throughout Europe and North America and has been widely cultivated. Much debate surrounds the safety of comfrey due to various parts and preparations containing potentially toxic alkaloids. It is important to understand that the part used, species, and time of harvest all come in to play when determining the safety of this herb. A large body of traditional use supports its safety and efficacy if used intelligently and cautiously.

Comfrey has a centuries-old tradition as a medicinal plant. Today, multiple randomized controlled trials have demonstrated the efficacy and safety of Comfrey preparations for the topical treatment of pain, inflammation and swelling of muscles and joints in degenerative arthritis, acute myalgia in the back, sprains, contusions and strains after sports injuries and accidents, also in children aged 3 or 4 and over.

BOTANY – A member of the Borage or Boraginaceae family, comfrey’s relatives include both borage (Borago sp.) and heliotrope (Heliotropium sp.). The Symphytum genus contains about 35 species, all of which can be used interchangeably, although pyrrolizidine alkaloid content varies between species and are highest in Russian comfrey (S. x uplandicum) and prickly comfrey or (S. asperum). Comfrey has large, rough, hairy, and lance-shaped leaves with whitish, pink, or purple flower spikes which have a slight heliotrope like curl typical of this family. It is native to much of Europe, and various regions in Asia such as the Caucasus, Kazakhstan, Siberia, and Turkey, and is commonly found as a weed in temperate northern latitudes.

The roots of leaves of the comfrey plant contain chemical substances called allantoin and rosmarinic acid. Allantoin boosts the growth of new skin cells, while rosmarinic acid helps relieve pain and inflammation. Extracts are still made from the roots and leaves and turned into ointments, creams, or salves. These solutions typically have a comfrey content of 5 to 20 percent.

The chief and most important constituent of Comfrey root is mucilage, which it contains in great abundance, more even than Marshmallow. It also contains from 0.6 to 0.8 per cent. of Allantoin and a little tannin. Starch is present in a very small amount.

Constituents of comfrey also include mucilage, steroidal saponins, tannins, pyrrolizidine alkaloids, inulin, and proteins.

Comfrey is rich in vitamin B12, which is important to vegans and vegetarians, as very few plants have B12, and is also rich in vitamins B1, B2, C, E, A, pantothenic acid plus calcium, iron, manganese, and phosphorus.

Uses for Comfrey

Even though this plant contains poisonous chemicals called pyrrolizidine alkaloids (PAs), the leaf, root, and root-like stem (rhizome) are used to make medicine. The amount of PAs found in comfrey changes according to the time of harvesting and the age of the plant. The roots have 10 times higher amounts of PAs than the leaves. Some products labeled “common comfrey” or Symphytum officinale actually contain the more poisonous “prickly comfrey” (Symphytum asperum) or “Russian comfrey” (Symphytum x uplandicum) species.

Comfrey is applied to the skin for ulcers, wounds, joint inflammation, bruises, rheumatoid arthritis, swollen veins (phlebitis), gout, and fractures

As the plant abounds in mucilage, it is frequently given whenever a mucilaginous medicine is required and has been used like Marshmallow for intestinal troubles. It is very similar in its emollient action to Marshmallow, but in many cases, is even preferred to it and is an ingredient in a large number of herbal preparations. It forms a gentle remedy in cases of diarrhea and dysentery. A decoction is made by boiling 1/2 to 1 OZ. of crushed root in 1 quart of water or milk, which is taken in wineglassful doses, frequently. For its demulcent action it has long been employed domestically in lung troubles and also for quinsy and whooping-cough. The root is more effectual than the leaves and is the part usually used in cases of coughs. It is highly esteemed for all pulmonary complaints, consumption and bleeding of the lungs. A strong decoction, or tea, is recommended in cases of internal hemorrhage, whether from the lungs, stomach, bowels or from bleeding piles -to be taken every two hours till the hemorrhage ceases, in severe cases, a teaspoonful of Witch Hazel extract being added to the Comfrey root tea.

Comfrey leaves are of much value as an external remedy, both in the form of fomentations, for sprains, swellings and bruises, and as a poultice, to severe cuts, to promote suppuration of boils and abscesses, and gangrenous and ill-conditioned ulcers. The whole plant, beaten to a cataplasm and applied hot as a poultice, has always been deemed excellent for soothing pain in any tender, inflamed or suppurating part. It was formerly applied to raw, indolent ulcers as a glutinous astringent. It is useful in any kind of inflammatory swelling.

The reputation of Comfrey as a vulnerary has been considered due partly to the fact of its reducing the swollen parts in the immediate neighborhood of fractures, causing union to take place with greater facility. Gerard affirmed: ‘A salve concocted from the fresh herb will certainly tend to promote the healing of bruised and broken parts.’ Surgeons have declared that the powdered root, if dissolved in water to a mucilage, is far from contemptible for bleedings and fractures, whilst it hastens the callus of bones under repair. Its virtues as a vulnerary are now attributed to the Allantoin it contains. According to Macalister (British Medical Journal, Jan. 6, 1912), Allantoin in aqueous solution in strengths of 0.3 per cent has a powerful action in strengthening epithelial formations, and is a valuable remedy not only in external ulceration, but also in ulcers of the stomach and duodenum. Comfrey Root is used as a source of this cell proliferant Allantoin, employed in the dealing of chronic wounds, burns, ulcers, etc., though Allantoin is also made artificially.

Comfrey roots, together with Chichory and Dandelion roots, are used to make a well-known vegetation ‘Coffee,’ that tastes practically the same as ordinary coffee, with none of its injurious effects.

A strong decoction has been used on the Continent for tanning leather, and in Angora a sort of glue is got from the common Comfrey, which is used for spinning the famous fleeces of that country.

USING COMFREY ROOT TO HEAL BROKEN BONES

Comfrey, otherwise known as Knit-Bone, is a miracle plant; and as its nickname suggests, is an herb esteemed for its ability to repair tissues & mend broken bones faster than any other plant. Comfrey has historically been used to help the knitting together of bones in cases of fractures.  It was a folklore remedy and its other names are Boneknit, Boneset, Healing Blade and even The Great Comfrey.

What Is Comfrey Oil?

Comfrey oil is extracted from comfrey (Symphytum officinale), a perennial herb of the Boraginaceae family with a black, turnip-like root and large, hairy broad leaves bearings small, bell-shaped flowers. The plant is native to Europe and grows in damp, grassy places such as ditches and riverbanks. It is typically found in Ireland and Britain on ditches and riverbanks, but it also grows in profusion in North America and western Asia.

The plant has found widespread use in folk and herbal medicine for its properties as a healing agent. Its oil, for instance, is ideal as a base for salves and has been used in folk medicine to treat wounds and skin infections.

Uses of Comfrey Oil  

Many of the beneficial properties of comfrey are attributed to its high content of allantoin, a substance that, according to the University of Maryland Medical Center, helps promote new skin cell growth, along with other substances that may work in reducing inflammation and maintaining healthy skin. Comfrey ointments have been used to help heal bruises and pulled muscles and ligaments.

Previously, comfrey was used in its tea form to aid in treating stomach problems, as well as ulcers, heavy menstrual periods, diarrhea, bloody urine, persistent cough and even cancer and chest pain. But experts have raised the alarm on consuming it, as it contains toxic substances called pyrrolizidine alkaloids (PAs), which damage the liver and can lead to fatality. According to the FDA, there is even evidence that PAs may be carcinogenic in sensitive body tissues when used orally.

The FDA reported this in 2001, when it sent letters to supplement manufacturers warning them not to put this herb in dietary supplements. Today, in the United States, comfrey is sold only in creams and ointments; countries like the United Kingdom, Australia, Canada and Germany have also banned the sale of comfrey-containing oral products.

But this isn’t to ignore the potential healing effects of a common comfrey product, which is its oil. Comfrey oil can help you naturally address wound healing and skin issues such as scratches, rash (including diaper rash), bug bites (particularly spiders) and shallow wounds. It is also deemed helpful as a massage salve easing pain from arthritis, muscle aches, low back pain and soreness.

Here are different comfrey oil benefits classified according to skin or health condition:

For skin rashes —– Comfrey oil can help in treating rashes. However, caution should be taken when it comes to deep wounds – the oil can help heal the skin so quickly that the new tissue may cover the wound before deep healing inside, resulting in an abscess or skin infection. Remember, too, that there are warnings against using comfrey on broken skin because its PAs can still be absorbed by your skin.

As a poultice — A poultice is a good alternative if you have an infection but don’t want to apply comfrey oil directly. Here’s how to do it: Blend 4 cups of chopped comfrey leaves and stems with 1/4 cup of carrier oil, such as jojoba, almond or olive oil. Without straining out the herb, wrap the comfrey oil paste with a cotton cloth. Freeze this poultice before applying to help reduce pain and inflammation. Otherwise, you may apply it directly on the affected area for at least 30 minutes.

For bone fractures — Apart from helping treat superficial wounds, comfrey oil has also been used for fractured bones or torn ligaments in areas of the body where it is not possible to place a cast, such as a rib. It can be applied directly onto your skin or in a poultice, potentially promoting faster healing. It is also said to help reconstruct torn muscles that might have been injured.

Modern Uses – Today, you may use topical or oral remedies containing comfrey root extract for many of the same traditional purposes. You might use topical comfrey root remedies to treat back pain, sprains and strains, bone fractures, bruises, varicose veins, conjunctivitis, skin ulcers and minor wounds. Although these are the proposed uses for comfrey root extract, you should talk with your health care provider before using comfrey herbal remedies.

Natural fibromyalgia remedy – Because fibromyalgia is associated with pain in various parts of the body, comfrey application might help to offer some relief. Again, stick to no more than 10 consecutive days of application. And limit use to four to six weeks per year. If you suffer from fibromyalgia pain, remember that your best option is to seek a multi-targeted approach to address whatever the root cause of this pain may be. Adjusting lifestyle to lose extra weight, eliminating problematic food ingredients like excitotoxins and eating anti-inflammatory foods may offer some additional relief.

Possibly Effective for:

Back pain. Applying a specific comfrey extract (Kytta-Salbe f by Merck Selbstmedikation GmbH) to the affected area for 5 days seems to decrease lower or upper back pain.

Osteoarthritis. Applying a specific comfrey extract (Kytta-Salbe f) to the affected area for 3 weeks or applying a specific cream containing comfrey extract, tannic acid, Aloe vera gel, eucalyptus oil, and frankincense oil (4Jointz) to the affected are for 12 weeks seems to decrease pain in people with knee osteoarthritis.

Sprains. Early research suggests that applying comfrey ointment to the affected area for up to 2 weeks improves mobility, decreases pain, and reduces tenderness and swelling of sprains. The effect of comfrey ointment in relieving pain and reducing swelling seems to be comparable to the effects of diclofenac gel. Most of the studies have used a specific comfrey ointment that is low in pyrrolizidine alkaloids (Kytta-Salbe f).

How to Use It

Application – To apply comfrey to affected skin areas, simmer 3 ½ ounces of fresh or dried peeled root in 1 pint of water for 10 or 15 minutes and soak a cloth in the liquid, says the University of Michigan Health System. Then, you can apply the cloth to the skin area for about 15 minutes several times each day. You can also use ointments or creams containing 25-percent comfrey root extract. Discuss this application method with your doctor first.

Pediatric – Never give a child comfrey by mouth. DO NOT put creams or ointments with comfrey on a child’s skin.

Adult – Never take comfrey by mouth. Severe liver poisoning and even death may occur. When using herb and leaf ointments, creams, and other preparations for the skin, follow these safety recommendations:

Never apply comfrey to broken skin. Use only small amounts of creams with comfrey for no longer than 10 days at a time. DO NOT use any comfrey product for more than 4 to 6 total weeks in one calendar year.

Medical Evidence

A 2004 double-blind study of 142 people suffering from ankle sprains found that applying comfrey root extract cream helped to reduce healing time, pain and swelling over the course of eight days, compared to placebo, says the University of Pittsburgh Medical Center. Another double-blind clinical trial published in 2009 found that comfrey root extract ointment helped to treat acute back pain, according to the Memorial Sloan-Kettering Cancer Center. A three-week-long, double-blind study of 220 people published in 2006 also found that comfrey root extract ointment relieved symptoms related to osteoarthritis of the knee, compared to placebo. A 2007 study of mice indicated that comfrey root extract had antiproliferative actions in hepatic cancer cells. Finally, a 2007 double-blind study of 278 people with fresh skin abrasions determined that applying a 10-percent concentration comfrey cream increased wound healing speed after just two to three days. None of these studies and clinical trials prove that comfrey root is safe and effective for treating any medical condition, so be sure to consult your physician before using comfrey remedies.

Precautions

Comfrey has toxic substances that can cause severe liver damage and even death. You should never take comfrey by mouth.

The toxic substances in comfrey can be absorbed by the skin. Even creams and ointments should be used for only a short time, and only under a doctor’s supervision.

DO NOT use comfrey on open wounds or broken skin.

DO NOT use comfrey if you have liver disease, alcoholism, or cancer.

The elderly and pregnant or breastfeeding women should not use comfrey products, even ones for the skin.

COMFREY SIDE EFFECTS & SAFETY

Today, eating or taking any form of comfrey by mouth isn’t recommended. It’s considered unsafe, due to the pyrrolizidine alkaloids that comfrey contains. These are dangerous chemicals that can cause cancer, severe liver damage, and even death when you consume them. For this reason, the Food and Drug Administration and European countries have banned oral comfrey products.

Comfrey is POSSIBLY SAFE for most people when applied to unbroken skin in small amounts for less than 10 days. It’s important to remember that the poisonous chemicals in comfrey can pass through the skin. Absorption of these chemicals increases if the skin is broken or if large amounts are applied.

Comfrey is LIKELY UNSAFE for anyone when taken by mouth. It contains chemicals (pyrrolizidine alkaloids, PAs) that can cause liver damage, lung damage, and cancer. The FDA has recommended removal of oral comfrey products from the market.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Comfrey is LIKELY UNSAFE to take by mouth or apply to the skin if you are pregnant or breast-feeding. In addition to causing liver damage and possibly cancer, the PAs in comfrey might also cause birth defects. Even topical use is unwise, since the PAs can be absorbed through the skin.

Broken or damaged skin: Don’t apply comfrey to broken or damaged skin. Doing so might expose you to large amounts of the chemicals in comfrey that can cause liver damage and other serious health effects.

Liver disease: There is a concern that comfrey might make liver disease worse. Don’t use comfrey if you have any problems with your liver.

Major Interaction Do not take this combination

Medications that can harm the liver (Hepatotoxic drugs) interacts with COMFREY

Comfrey might harm the liver. Taking comfrey along with medication that might also harm the liver can increase the risk of liver damage. Do not take comfrey if you are taking a medication that can harm the liver.

Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin), lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.

Moderate Interaction Be cautious with this combination

Medications that increase the breakdown of other medications by the liver (Cytochrome P450 3A4 (CYP3A4) inducers) interacts with COMFREY

Comfrey is broken down by the liver. Some chemicals that form when the liver breaks down comfrey can be harmful. Medications that cause the liver to break down comfrey might enhance the toxic effects of chemicals contained in comfrey.

Some of these medicines include carbamazepine (Tegretol), phenobarbital, phenytoin (Dilantin), rifampin, rifabutin (Mycobutin), and others.

Recipes

How to Make Your Own Comfrey Oil Infusion – Create an herbal oil infusion by infusing 2 cups of cut comfrey leaves in 4 cups of olive oil with a steady low heat (110 degrees) for two to three weeks. Strain and pour into a clean, dry bottle.

References:

  1. https://www.mountainroseherbs.com/products/comfrey-root-powder/profile
  2. https://www.webmd.com/vitamins-supplements/ingredientmono-295-comfrey.aspx?activeingredientid=295&activeingredientname=comfrey
  3. https://kauaifarmacy.com/using-comfrey-root-to-heal-bones/
  4. https://www.healthline.com/health/what-is-comfrey
  5. https://www.botanical.com/botanical/mgmh/c/comfre92.html
  6. https://articles.mercola.com/herbal-oils/comfrey-oil.aspx
  7. https://en.wikipedia.org/wiki/Comfrey
  8. http://www.gardenorganic.org.uk/about_us/history.php
  9. http://gardenofeaden.blogspot.com/2010/05/how-to-grow-comfrey.html
  10. https://notdabblinginnormal.wordpress.com/2009/05/15/everything-you-always-wanted-to-know-about-comfrey-but-were-afraid-to-ask/
  11. http://www.dailymail.co.uk/home/article-1048976/Comfrey-compost-The-superfood-plants.html
  12. http://www.hort.purdue.edu/newcrop/afcm/comfrey.html
  13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3580139
  14. http://www.umm.edu/altmed/articles/comfrey-000234.htm
  15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2399473
  16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259911/
  17. https://wellnessmama.com/8230/comfrey-leaf-herb-profile/
  18. https://draxe.com/comfrey/
  19. https://doi.org/10.1001%2Farchinte.158.20.2200
  20. https://doi.org/10.1111%2Fj.1440-1746.1990.tb01827.x
  21. http://www.fda.gov/Food/RecallsOutbreaksEmergencies/SafetyAlertsAdvisories/ucm111219.htm
  22. https://doi.org/10.1017%2Fs1368980000000586
  23. http://www.umm.edu/health/medical/altmed/herb/comfrey
  24. https://www.livestrong.com/article/156691-what-is-comfrey-root-extract/
  25. https://remedygrove.com/remedies/How-to-use-Comfrey-to-Heal-Broken-Bones
  26. http://www.askanaturopath.com/faqs/comfrey-question/p/156
  27. http://herbclass.com/comfrey-speeds-healing/
  28. https://taniamarieartist.wordpress.com/2012/02/29/comfrey-poultices-bone-mending-magick/
  29. Abbott, P. J. Comfrey: assessing the low-dose health risk. Med.J.Aust. 12-5-1988;149(11-12):678-682. View abstract.
  30. Aftab, K., Shaheen, F., Mohammad, F. V., Noorwala, M., and Ahmad, V. U. Phyto-pharmacology of saponins from Symphytum officinale L. Adv Exp Med Biol 1996;404:429-442. View abstract.
  31. Ahmad, V. U., Noorwala, M., Mohammad, F. V., and Sener, B. A new triterpene glycoside from the roots of Symphytum officinale. J Nat Prod. 1993;56(3):329-334. View abstract.
  32. Altamirano, J. C., Gratz, S. R., and Wolnik, K. A. Investigation of pyrrolizidine alkaloids and their N-oxides in commercial comfrey-containing products and botanical materials by liquid chromatography electrospray ionization mass spectrometry. J AOAC Int 2005;88(2):406-412. View abstract.
  33. Barbakadze, V. V., Kemertelidze, E. P., Targamadze, I. L., Shashkov, A. S., and Usov, A. I. [Novel biologically active polymer of 3-(3,4-dihydroxyphenyl)glyceric acid from two types of the comphrey Symphytum asperum and S. caucasicvum (Boraginoceae)]. Bioorg.Khim. 2002;28(4):362-366. View abstract.
  34. Barna, M., Kucera, A., Hladicova, M., and Kucera, M. [Wound healing effects of a Symphytum herb extract cream (Symphytum x uplandicum NYMAN: ): results of a randomized, controlled double-blind study]. Wien.Med.Wochenschr. 2007;157(21-22):569-574. View abstract.
  35. Barna, M., Kucera, A., Hladikova, M., and Kucera, M. Randomized double-blind study: wound-healing effects of a Symphytum herb extract cream (Symphytumxuplandicum Nyman) in children. Arzneimittelforschung. 2012;62(6):285-289. View abstract.
  36. Barthomeuf, C. M., Debiton, E., Barbakadze, V. V., and Kemertelidze, E. P. Evaluation of the dietetic and therapeutic potential of a high molecular weight hydroxycinnamate-derived polymer from Symphytum asperum Lepech. Regarding its antioxidant, antilipoperoxidant, antiinflammatory, and cytotoxic properties. J Agric.Food Chem 2001;49(8):3942-3946. View abstract.
  37. Behninger, C., Abel, G., Roder, E., Neuberger, V., and Goggelmann, W. [Studies on the effect of an alkaloid extract of Symphytum officinale on human lymphocyte cultures]. Planta Med. 1989;55(6):518-522. View abstract.
  38. Betz, J. M., Eppley, R. M., Taylor, W. C., and Andrzejewski, D. Determination of pyrrolizidine alkaloids in commercial comfrey products (Symphytum sp.). J Pharm Sci 1994;83(5):649-653. View abstract.
  39. Bleakley, C. M., McDonough, S. M., and MacAuley, D. C. Some conservative strategies are effective when added to controlled mobilisation with external support after acute ankle sprain: a systematic review. Aust.J Physiother. 2008;54(1):7-20. View abstract.
  40. Brauchli, J., Luthy, J., Zweifel, U., and Schlatter, C. Pyrrolizidine alkaloids from Symphytum officinale L. and their percutaneous absorption in rats. Experientia 9-15-1982;38(9):1085-1087. View abstract.
  41. Couet, C. E., Crews, C., and Hanley, A. B. Analysis, separation, and bioassay of pyrrolizidine alkaloids from comfrey (Symphytum officinale). Nat.Toxins. 1996;4(4):163-167. View abstract.
  42. Culvenor, C. C., Clarke, M., Edgar, J. A., Frahn, J. L., Jago, M. V., Peterson, J. E., and Smith, L. W. Structure and toxicity of the alkaloids of Russian comfrey (symphytum x uplandicum Nyman), a medicinal herb and item of human diet. Experientia 4-15-1980;36(4):377-379. View abstract.
  43. D’Anchise, R., Bulitta, M., and Giannetti, B. Comfrey extract ointment in comparison to diclofenac gel in the treatment of acute unilateral ankle sprains (distortions). Arzneimittelforschung. 2007;57(11):712-716. View abstract.
  44. Dasgupta, A. Review of abnormal laboratory test results and toxic effects due to use of herbal medicines. Am J Clin Pathol 2003;120(1):127-137. View abstract.
  45. Di Mambro, V. M. and Fonseca, M. J. Assays of physical stability and antioxidant activity of a topical formulation added with different plant extracts. J Pharm Biomed Anal. 2-23-2005;37(2):287-295. View abstract.
  46. Dolganiuc, A., Radu, L. D., and Olinescu, A. [The effect of products of plant and microbial origin on phagocytic function and on the release of oxygen free radicals by mouse peritoneal macrophages]. Bacteriol.Virusol.Parazitol.Epidemiol. 1997;42(1-2):65-69. View abstract.
  47. Fijalkowski, D. and Seroczynska, M. Herba ol. 1977;23:47.
  48. Franz, G. [Studies on the mucopolysaccharides of Tussilago farfara L., Symphytum officinalis L., Borago officinalis L. and Viola tricolor L]. Planta Med 1969;17(3):217-220. View abstract.
  49. FRIES, B. [Obstructive ileus after ingestion of comfrey (radix Symphyti).]. Sven.Lakartidn. 10-2-1953;50(40):2085-2087. View abstract.
  50. Furmanowa, M., Guzewska, J., and Beldowska, B. Mutagenic effects of aqueous extracts of Symphytum officinale L. and of its alkaloidal fractions. J Appl Toxicol 1983;3(3):127-130. View abstract.
  51. Furuya, T. and Araki, K. Studies on constituents of crude drugs. I. Alkaloids of Symphytum officinale Linn. Chem Pharm Bull.(Tokyo) 1968;16(12):2512-2516. View abstract.
  52. Giannetti, B. M., Staiger, C., Bulitta, M., and Predel, H. G. Efficacy and safety of comfrey root extract ointment in the treatment of acute upper or lower back pain: results of a double-blind, randomised, placebo controlled, multicentre trial. Br.J Sports Med. 2010;44(9):637-641. View abstract.
  53. Gray, D. E., Porter, A., O’Neill, T., Harris, R. K., and Rottinghaus, G. E. A rapid cleanup method for the isolation and concentration of pyrrolizidine alkaloids in comfrey root. J AOAC Int 2004;87(5):1049-1057. View abstract.
  54. Grube, B., Grunwald, J., Krug, L., and Staiger, C. Efficacy of a comfrey root (Symphyti offic. radix) extract ointment in the treatment of patients with painful osteoarthritis of the knee: results of a double-blind, randomised, bicenter, placebo-controlled trial. Phytomedicine. 2007;14(1):2-10. View abstract.

Leave a Reply