Comfrey: Ancient bone mender or liver damaging poison?

Herbalism

Sep 29

*The information shared in this podcast is for educational purposes only. While I strive to present accurate, evidence-based information, this content is not intended as medical advice, nor should it replace guidance from a qualified healthcare professional. Herbs, supplements, and natural products can affect everyone differently, may interact with medications, and are not appropriate for every individual. Always consult your physician, pharmacist or other qualified healthcare provider before using herbal products or making changes to your healthcare routine, and never consume or handle wild plants without proper identification and appropriate knowledge.

Botanical Profile

Comfrey, or Symphytum officinale, is a member of the Boraginaceae family; the same family as borage, Forget-me-nots, and Virginia bluebells.

It’s native to parts of Europe and Asia but has been naturalized in many places, including North America.

Comfrey prefers damp areas with full sun and grows in dense clumps, reaching 3-5 feet tall and 2-3 feet wide. It is covered in coarse hairs and has broad leaves that can grow more than 8 inches long (1). It also has long stems that grow from the center of the plant, on the ends of which grow bell shaped flowers in shades of purple, pink, blue or white.

There are 35 known species of comfrey, but today when I mention comfrey, I’m specifically referring to Common Comfrey.

Ecological Significance

Comfrey is incredibly beneficial to the environment.

With roots burrowing 6 to 10 feet deep, it pulls up nutrients that would otherwise remain inaccessible to other plants. (3)

Because it can access these nutrients, the plant itself is very nutrient rich, making it great for fertilizer, mulch and compost. You can steep the leaves in water to make a balanced fertilizer that won’t burn your plants, lay the leaves down like mulch to suppress weeds, provide nutrients, and enrich the soil, and add it to your compost, where the nitrogen rich leaves help speed up decomposition and balance carbon heavy substrates such as wood chips or dried autumn leaves. (4)

While the leaves add nutrients to the soil, comfrey’s deep roots help soil health by breaking up compacted earth, creating channels for air, water and beneficial insects like earthworms. They also help hold soil in place, helping prevent soil erosion. (4)

Comfrey is also a friend to beneficial insects. The flowers provide nectar for bees and butterflies well into the summer, and the dense foliage provide shelter for ground beetles and other insects that eat pests, helping keep your garden healthy. (4)

Traditional Use

Aside from being nutrient rich, comfrey contains multiple beneficial compounds, including mucilage, allantoin, and rosmarinic acid. (5) (10)

Mucilage is a gelatinous substance that helps protect plants from microorganisms and germinate seeds. Because this gelly is cooling and moistening, plants that produce mucilage have been used topically to hydrate and protect the skin, and to soothe irritation and wounds such as cuts and burns. (6)

Allantoin is a naturally occurring chemical produced by our bodies, and by some plants. It’s often found in skincare products, as it stimulates cell turnover, helps hydrate and moisturize the skin, and is antimicrobial. (7)

Rosmarinic acid is a compound found in plants that has anti-oxidative, anti-inflammatory, and neuroprotective effects on the body. (8)

While our ancestors didn’t have labs and microscopes to detect these compounds, they understood that comfrey has beneficial effects on the body and used it to treat a variety of ailments.

Comfrey has been used as far back as 400 BCE, with the ancient Greeks and Romans. (3)

It’s most known for helping mend broken bones, earning it the nickname ‘knitbone’, but has also been used to treat digestive problems, lung problems, arthritis, ulcers, bruises, strains & sprains, burns, gum disease, sore throats, hemorrhoids, varicose veins, chest colds, athlete's foot, cuts, excessive menstrual bleeding, and chest pain. (9)

Modern research supports comfrey’s topical use for pain, strains & sprains, bruises. inflammation, and the swelling of muscles and joints. It has also been shown to stimulate granulation (a stage in wound healing where new connective tissue is formed) and tissue regeneration, and supports callus formation. (10)

Cautions & Toxic Compounds

As mentioned, comfrey was historically used internally to treat conditions like ulcers and digestive problems, but this is no longer recommended, as comfrey has been found to contain pyrrolizidine alkaloids, which can cause damage to the liver if ingested. (9) (10) Furthermore, the liver damage causes no noticeable symptoms until it reaches an advanced stage, so there are no warning signs to signal you should stop using it before it’s too late. (11)

These alkaloids are more concentrated in the root and in older leaves, with younger leaves containing very small amounts. (12) They are poorly soluble in oil, so infused oils and salves will only contain small amounts of them. (11) (9) Even so, comfrey should not be used internally, long term, or on broken skin, especially on deep or infected wounds. The reason it should not be used on deep or infected wounds is actually due to its healing abilities, which seems counterintuitive, but the compounds in comfrey are so good at helping with cell turnover, that it can heal the top layer of skin, trapping pathogens in the deeper, unhealed layers, which can lead to an abscess. (11)

History & Folklore

Comfrey’s reputation as a bone healer has earned it many nicknames, including Healing Herb, Knitback, Knitbone, Boneset and Bruisewort. (9).

Boneset is the common name of another plant used in herbal medicine. To avoid confusion, the latin name for Boneset is Eupatorium perfoliatum, and as mentioned, the latin name for Comfrey is Symphytum officinale.

Comfrey is also sometimes referred to as Ass Ear (9), due to its resemblance to the ear of a donkey.

The genus portion of the Latin name (Symphytum) comes from two Greek words: ‘symphyo’, which means “to grow together” and “phyton”, which means plant. The species portion of the name (officinale) indicates that the plant was used for medicinal purposes. (13)

Comfrey has long been used in magical practices for protection, luck, and prosperity. (14)

It was traditionally kept in purses or wallets, placed near cash registers, or rubbed over money with the belief that any money spent would be returned. Comfrey was also popular among gamblers, who kept it alongside their gambling money in hopes of attracting good luck and large winnings. (14)

For protection, comfrey has been a popular herb among travellers. It was traditionally carried in luggage, kept in cars, or tucked into shoes and pockets to ensure a safe journey and ward off negative entities one may encounter along the way. It was also planted near doors and windows to ward off thieves, and kept near those practising astral travel, for protection and to ensure their soul returned safely to their body. (14)

Sources

1 - https://hortsense.cahnrs.wsu.edu/fact-sheet/weeds-comfrey-symphytum-officinale/

2 - https://practicalselfreliance.com/comfrey-symphytum-sp/

3 - https://www.permaculture.co.uk/articles/comfrey-its-history-uses-benefits/

4 - https://positivebloom.com/convincing-reasons-you-should-grow-comfrey-in-your-garden-and-how-to-use-it-right/

5 - https://www.ages.at/en/human/pharmaceuticals-medical-devices/medicinal-plants/comfrey

6 - https://www.botanical-online.com/en/medicinal-plants/mucilage

7 - https://health.clevelandclinic.org/allantoin

8 - https://www.sciencedirect.com/topics/neuroscience/rosmarinic-acid

9 - https://www.canada.ca/content/dam/dnd-mdn/documents/health/nutrition/supplement-fact-sheet-comfrey.pdf

10 - https://pmc.ncbi.nlm.nih.gov/articles/PMC3491633/

11 - Commonwealth Herbs, Family Herbalist program, Materia Medica course