The Severe Risks of Eating Raw Comfrey
For centuries, comfrey has been a fixture in folk medicine, revered for its ability to heal external wounds and mend bones—earning it the nickname "knitbone". However, modern scientific understanding has revealed a dark side to this traditional remedy, making internal consumption, especially raw, extremely dangerous. The primary culprit is a group of chemicals called pyrrolizidine alkaloids (PAs). These compounds are hepatotoxic, meaning they are poisonous to the liver and can cause severe, irreversible damage.
What are Pyrrolizidine Alkaloids?
Pyrrolizidine alkaloids are naturally occurring substances found in many plants, including comfrey. When ingested, PAs are metabolized by the liver into highly reactive toxic metabolites. This process can damage the small veins in the liver, leading to a condition known as veno-occlusive disease (VOD). VOD is a serious and potentially fatal condition where blood flow through the liver is blocked, leading to severe liver injury, cirrhosis, and liver failure. Ingestion of comfrey-containing products has been linked to numerous cases of VOD and death. Animal studies also show that PAs can cause cancer.
Official Warnings and Market Bans
Due to the well-documented risks associated with internal use, multiple health agencies have issued strong warnings against consuming comfrey.
- The U.S. FDA has advised all dietary supplement manufacturers to remove comfrey products intended for internal use from the market.
- Health Canada has also issued warnings, advising against ingesting any health product containing comfrey due to the risk of liver-damaging PAs.
- Most countries have banned or restricted the sale of oral comfrey preparations due to these serious safety concerns.
Despite historical use, the scientific community is now unified in its position that the internal consumption of comfrey is unsafe.
Comparison of Comfrey Uses: Safe vs. Unsafe
The most important distinction to understand is the difference between internal consumption and topical application. The following table clarifies the applications and associated risks.
| Aspect | Internal Consumption (Raw, Cooked, Tea, Supplement) | External Application (Unbroken Skin) |
|---|---|---|
| Health Risk | Extremely High: Liver damage (VOD), liver failure, potential cancer. | Low, but requires caution: Some skin irritation or allergic reactions possible. |
| Active Compounds | Toxic pyrrolizidine alkaloids are absorbed and metabolized by the liver, causing damage. | Active ingredients like allantoin and rosmarinic acid may be absorbed in small amounts, offering anti-inflammatory benefits without high PA load. |
| Regulatory Status | FDA-banned for oral products; not recommended by experts. | Potentially safe for short-term, supervised use on unbroken skin. |
| Historical Practice | Used in folk medicine for various internal ailments despite the risks. | Long-standing traditional use for bruises, sprains, and closed wounds. |
| Modern Recommendation | Avoid completely. | Use with caution on unbroken skin for short periods (less than 10 days). |
Safe Topical Applications
Even when used topically, there are important safety guidelines to follow. The poisonous PAs can be absorbed through the skin, so care must be taken to minimize exposure.
- Use on unbroken skin only: Never apply comfrey to open wounds, cuts, or damaged skin. The risk of absorption through compromised skin is significantly higher.
- Limit duration: Topical use should be limited to short periods, typically no more than 10 days in a row, with a total annual usage not exceeding 4 to 6 weeks.
- Consider product type: Comfrey is often used in salves, ointments, or poultices. These should be applied carefully and sparingly.
The Allure of Comfrey and the All-Important Warning
Comfrey's historical reputation for its wound-healing and anti-inflammatory properties, largely attributed to compounds like allantoin, has unfortunately perpetuated the dangerous misconception of its edibility. The plant’s leaves and roots contain different concentrations of PAs, with the roots generally containing higher levels. However, this is not a reliable safety metric, as all parts contain PAs and are considered unsafe for internal consumption. The serious and potentially fatal consequences of PA-induced liver damage far outweigh any purported benefits of internal consumption.
Furthermore, the varying levels of PAs in different comfrey species (e.g., Russian comfrey vs. Common comfrey) and inconsistent concentrations based on growing conditions make it impossible to determine a "safe" amount for ingestion. The safest and only recommended approach is to avoid internal consumption entirely. For documented information from a reliable source, see the National Center for Biotechnology Information entry on comfrey hepatotoxicity.
A Conclusion on Comfrey Consumption
In summary, while comfrey holds a long history in external folk medicine, the answer to the question "Can comfrey be eaten raw?" is a definitive and resounding no. Modern scientific research has conclusively demonstrated the high risk of severe liver damage and failure due to toxic pyrrolizidine alkaloids, leading to regulatory bans on oral comfrey products in numerous countries. The risks of internal consumption far outweigh any perceived benefits. For those wishing to use comfrey, topical application on unbroken skin for short periods is the only recommended method, and even that should be approached with caution.
Frequently Asked Questions
Q: Is any part of the comfrey plant safe to eat? A: No, all parts of the comfrey plant contain liver-toxic pyrrolizidine alkaloids and are considered unsafe for internal consumption, whether raw or cooked.
Q: Can comfrey be prepared in a way that makes it safe to eat? A: No. Cooking or drying comfrey does not eliminate the pyrrolizidine alkaloids that cause liver damage.
Q: Can you make and drink comfrey tea? A: No, drinking comfrey tea is dangerous. PAs are water-soluble and can be extracted into the tea, leading to liver toxicity. The FDA has banned oral comfrey products, including teas.
Q: Is it safe to apply comfrey topically to the skin? A: Topical application on unbroken skin is possibly safe for short durations (less than 10 days). However, it should never be applied to open wounds, cuts, or damaged skin.
Q: What are the symptoms of comfrey poisoning? A: Ingesting comfrey can lead to liver damage, potentially causing symptoms such as jaundice (yellowing skin), pain in the upper abdomen, nausea, and fluid retention.
Q: Is it safe to feed comfrey to livestock or animals? A: No, comfrey is also toxic to livestock, and its use as a commercial animal food source has been banned in many places due to the PA content.
Q: How is comfrey used safely, if not for eating? A: Comfrey is best used for external, topical applications on unbroken skin, or in the garden. It is a potent fertilizer and compost accelerator.
Q: Why was comfrey used in the past if it's so dangerous? A: Historically, the dangers of pyrrolizidine alkaloids were unknown. Traditional use relied on observation rather than scientific understanding of its long-term effects on the liver.
Q: How do I tell comfrey apart from other plants? A: Comfrey has large, hairy, lance-shaped leaves and produces clusters of purple, white, or pink bell-shaped flowers. However, it is easily mistaken for other plants, including the deadly foxglove, so proper identification is crucial.
Key Takeaways
- Raw Comfrey is Extremely Unsafe: All parts of the comfrey plant contain liver-toxic pyrrolizidine alkaloids, making internal consumption highly dangerous.
- FDA Bans Oral Products: Due to the severe risk of liver damage, regulatory bodies like the FDA have banned oral comfrey products from the market.
- Toxicity Varies, but Danger Remains: While PA levels differ between plant parts (roots higher) and species, all varieties contain toxic alkaloids and pose an unacceptable risk when ingested.
- Avoid Internal Consumption Completely: The risk of veno-occlusive disease, liver failure, and potential cancer makes eating, drinking, or supplementing with comfrey unwise.
- Topical Use Only on Unbroken Skin: Topical application is only advised on unbroken skin for short periods, and should be completely avoided on open wounds.
- Use Caution and Identify Correctly: Never consume wild comfrey without absolute certainty of its identity, as it can be confused with other toxic plants like foxglove.
Citations
- WebMD. Comfrey - Uses, Side Effects, and More. http://www.webmd.com/vitamins/ai/ingredientmono-295/comfrey
- ResearchGate. The efficacy and safety of comfrey. https://www.researchgate.net/publication/12057686_The_efficacy_and_safety_of_comfrey
- NCBI Bookshelf. Comfrey - LiverTox. https://www.ncbi.nlm.nih.gov/books/NBK548370/
- Deep Roots Project. Growing and Using Comfrey. https://www.deep-roots-project.org/grow-your-own-food-all/growing-and-using-comfrey
- The Kinnard Homestead. The Complete Guide to Comfrey. https://www.thekinnardhomestead.com/resources/the-complete-guide-to-comfrey/
