Comfrey, scientifically known as Symphytum officinale, is a perennial herb with a deep history in traditional medicine across Europe and Asia. The plant is easily recognizable by its large, hairy leaves and bell-shaped flowers, which typically range in color from purple to cream. For over 2,000 years, comfrey has been utilized by herbalists, earning the evocative common name “Knitbone” due to its reputed ability to help mend sprains, bruises, and even bone fractures. This long-standing reputation as a powerful healing agent has led many people to explore its use in various forms, including as a brewed beverage. The plant contains a potent mix of compounds, including allantoin and rosmarinic acid, which contribute to its anti-inflammatory and wound-healing properties, making it a subject of enduring interest.
Step-by-Step Guide to Preparation
Traditional methods for preparing comfrey as a tea, or infusion, focus on extracting the compounds from the harvested plant material. The first step involves sourcing the herb, with both the leaves and the roots being used, although the roots generally contain higher concentrations of the plant’s constituents. Whether using fresh or dried material, the leaves should be cleaned of any dirt and then coarsely chopped to expose more surface area. Using dried material is often preferred for a tea intended for consumption, as the drying process can slightly alter the chemical profile.
To create the infusion, a ratio of dried comfrey to hot water is typically used, such as one to two teaspoons of dried herb per cup of water. The choice of plant part is significant because comfrey roots contain more of the compounds relevant to this discussion than the leaves do. Boiling water should be poured over the chopped or dried material, and the mixture is allowed to steep for approximately 10 to 15 minutes before straining.
It is important to note that these steps describe the traditional method for creating a comfrey infusion historically taken internally. Historically, people would drink this liquid straight, or sometimes sweetened with honey, believing it would aid internal ailments like stomach issues or diarrhea. This method is detailed here to inform the reader of the traditional preparation, but this practice is now universally discouraged.
Severe Health Risks of Ingesting Comfrey
The primary reason to avoid drinking comfrey tea is the presence of toxic compounds called Pyrrolizidine Alkaloids (PAs). Comfrey contains several different PAs, including echimidine, symphytine, and lycopsamine, which are highly damaging to the body when ingested. The concentration of these toxic alkaloids varies depending on the species of comfrey and the part of the plant used, but all oral consumption carries a significant risk.
When comfrey is consumed, the PAs are metabolized in the liver into highly reactive pyrrole metabolites. These metabolites are powerful alkylating agents that can damage the endothelial cells lining the small veins of the liver. This damage leads to a condition known as veno-occlusive disease (VOD), or sinusoidal obstruction syndrome (SOS), where the small hepatic veins become blocked. The resulting obstruction can cause severe liver injury, potentially leading to cirrhosis and liver failure.
Due to this danger, many international regulatory bodies, including the United States Food and Drug Administration (FDA), have banned or severely restricted the sale of oral comfrey products. Even low-level or chronic ingestion can cause liver damage. Specific populations are at a much higher risk, including individuals with pre-existing liver conditions. Pregnant and nursing women are also strongly advised against any internal use, as the toxic PAs can cross the placenta and be transferred through breast milk.
Safe External Application and Usage
While internal consumption is unsafe, comfrey has a well-established and safer history of use as a topical remedy. The herb’s anti-inflammatory and cell-regenerating properties are primarily attributed to compounds like allantoin and rosmarinic acid. These compounds are effectively absorbed through intact skin, making external application the preferred method for utilizing the herb’s benefits.
Comfrey is commonly applied topically to address musculoskeletal issues such as sprains, bruises, and joint pain. Preparations include oils, salves, and poultices made from the leaves or roots. A poultice is created by crushing the fresh or dried plant material into a paste, often with a binder like flour, and applying it directly to the affected area. Topical use is considered generally safe because PAs are poorly absorbed through healthy skin, provided the skin is not broken or deeply wounded.
Comfrey for Gardening
A completely different, non-health-related application is the creation of comfrey liquid fertilizer, often called “comfrey tea” by gardeners. This liquid is made by steeping large quantities of comfrey leaves in water for several weeks, allowing them to decompose and release their nutrients. Comfrey is a deep-rooted plant that pulls up high concentrations of minerals, especially potassium, making this concentrated liquid a valuable, organic plant food. This garden tea is strictly for plants, not people, and is typically diluted with water before application to boost the growth and fruiting of crops like tomatoes.