What is Comfrey?

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“10 Essential Herbs” by Lalitha Thomas is a detailed guide to botanical medicine.
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Comfrey is famous for its high amount of naturally occurring allantoin, a potent “cell proliferant” that means it actively catalyzes the growth of new cells.

Take the guesswork out of botanicals with 10 Essential Herbs (One World Press, 2011) by Lalitha Thomas. Heralded as the herb book for the self sufficient, it is a handbook to perfect health. Unlock the mysteries of the powerful herb, comfrey, in the following excerpt.

You can purchase this book from the Mother Earth Living store: 10 Essential Herbs.


Symphytum officinale

Miss Comfrey rejuvenates blood and new skin;
Helping inside and out, she’s a real gem.
She clears inflammation, works alone or with more
To mend bleeding and burns, broken bones to the core.

What is Comfrey?

Comfrey has some potent and unique characteristics that are very unusual in the world of plants. Comfrey is famous for its high amount of naturally occurring allantoin, which is found primarily in its roots, but in its leaves as well. Allantoin is a potent “cell proliferant,” which means that it actively catalyzes the growth of new cells in all body tissue including bones.

Allantoin also hastens the cleanup of septic, sloughing surfaces (dead, diseased or slow-healing tissues) making way for the fast, new growth of healthy tissues. In healing flesh and bones, it is well known that new cells will not readily grow and rebuild over septic (diseased) surfaces. While allantoin itself is not antiseptic, it catalyzes growth of leucocytes in the blood, which are our natural infection-fighters and infection preventives. Allantoin acts like a hormone in that even small quantities can catalyze large, positive changes in the body’s ability to slough off diseased cells and rehabilitate with healthy ones. Comfrey is no ordinary herb!

The History of Comfrey and Allantoin

As early as the 16th century in England, doctors were using and writing about comfrey’s potent cell proliferating qualities. This was long before scientists identified the presence of allantoin. Later, allantoin was found to be an active agent in fetal development and in mother’s milk where it helps the baby to grow.

Although allantoin on its own has been proven extremely effective in its healing abilities, there are many other properties of comfrey that work with allantoin to enhance its action. These include comfrey’s strong collection of usable proteins, its rare ability to make available significant amounts of vitamin B12, and the mucilaginous quality of its leaves and roots, which make it extremely soothing to irritated mucous membranes and other inflamed areas. Keep in mind that in herbistry every plant has many properties that work together to enhance each other, and that often, when a so-called “active ingredient” is extracted from a plant and used on its own, we lose this valuable interaction.

Comfrey is most potent when properly prepared. Allantoin is much more soluble in hot water than in cold, yet it begins decomposing quickly with prolonged heat, especially past the boiling point. Allantoin is also at its best when it is not prepared in hard water or left standing in its brewed form for more than 24 hours. What all this means is that for the most potent preparation of comfrey root and leaves, you need to brew the comfrey in distilled or soft water, bringing it just to the boiling point; steep it with a lid on for the needed length of time (10 minutes to 30 minutes, most commonly), and then use it immediately, or at least within 24 hours. For these reasons it is best to have comfrey root powdered or chopped in small bits so it steeps easily and quickly. The dried or fresh leaves are easily torn or crumbled for convenient use. The idea is to have the most surface area of the comfrey parts in contact with the hot water or other extracting medium. Sometimes, if the brew seems not as strong as I think it should be yet it has already cooled off and therefore is not continuing to extract the herb properly, I gently bring it back up to heat and let it sit some more. These “fine points” of comfrey preparation will definitely enhance the potency of the herb usage yet are not so crucial that they ruin comfrey’s effectiveness if they are not followed. Even if you were to lightly simmer the root in regular tap water (as many people do) you could still expect substantial help from this powerful herb.

The Root of Comfrey

Comfrey grows most easily from root cuttings. It is a plant that you will always want to take with you and start growing—indoors or outdoors—wherever you happen to be living. I have taken comfrey root “starts” with me from the east coast to the southwest of the United States and have found that it will grow in a wide variety of circumstances. Comfrey roots should be harvested when the highest concentrations of allantoin are present, during the dormant winter months of January through March. At this time the plant is getting ready for renewed efforts of cell growth in spring, and has concentrated all its resources in the roots. Harvest the roots by digging them up, peeling off their rough external layer, and chopping them into smallish bits (you’ll need a small hand-axe or large, sharp knife) for quick drying and more efficient preparation in the future. The roots will be quite moist. To guard against mold forming on them during drying, lay them out in thin layers on brown paper out of direct sunlight (this is great in hot and dry climates) or perhaps dry them in a low oven (100 to 120 degrees).

If you are not a plant-growing person, you can always get the dried leaves and roots at an herb store. Properly dried comfrey leaves keep much of their deep green color, so don’t buy them if they look all brown or greyish. Dried comfrey root should be varying shades of cream to tan. If it looks blackish it may have been processed improperly. Once comfrey is planted, it’s there for good. Comfrey roots go very deeply into the soil, somewhat like tree roots, and root-portions left in the soil after harvesting will start a new comfrey plant in the spring.

By April and May, allantoin concentrations in the comfrey roots are already beginning to lessen. That’s when allantoin starts moving up—proliferating cells for the growth of fresh stems, leaves, and springtime flowers. While allantoin concentration in stems and leaves is never as dramatic as the amount the winter roots· hold, the leaves (especially) and the stems (to the least degree) still hold significant and usable amounts of allantoin along with vitamins, minerals, and protein, which add to comfrey’s healing properties and make it an important food crop for humans (it can be prepared like spinach, fresh or cooked) and farm animals as well. The flowers are beautiful, and can be eaten, yet hold no significant amounts of allantoin. Therefore, the most “finicky” time for harvesting mature comfrey leaves is anytime before or after the plant flowers. This is when the nutritive and allantoin properties are most potent in the leaves as they are not being directed toward the making of flowers or being withdrawn back into the roots in late fall for winter storage.

Harvesting Comfrey

To harvest the mature leaves simply pick off a few and use them fresh, or cut leaves off—stems and all—and hang them upside down in bunches in a well shaded and dry area (indoors or out) until the leaves are well dried. Then it is easy to rub the leaves off the larger main stems (small, tender stems often stay with the leaf) into a bag or jar for storage somewhere dark and dry, as in a cupboard. Any leftover larger stems are great to put into the compost.

None of this is meant to intimidate you into thinking that you absolutely must stick to this time schedule of harvesting or must necessarily grow your own plants to get good results with comfrey. Rather it is meant to point out when you can get the maximum potency from your comfrey. I use any part of my fresh comfrey plant whenever a need arises, no matter what time of the year it is. But if I am harvesting for later use, then I pay attention to the most potent harvesting times. In the case of using dried comfrey purchased from an herb store, you have to assume that the commercial harvesters knew what they were doing. (Of course you’ll check for proper color anyway, right?) Given the good results that most people have with purchased comfrey, I would guess that such optimism is quite realistic.

Uses for Comfrey

When I first learned about all the ways to use comfrey, I often got stumped trying to decide which part of the plant—root or leaf—to use for any given situation. Many of my herbalist friends would just say, “Use comfrey for such-and-such,” and if I didn’t think to clarify exactly how to prepare it or apply it, I would get home and begin to question how to use it. Often I would be living in such secluded circumstances that it was not possible to make telephone contact when questions arose, so I sometimes felt anxious that I was using roots and leaves interchangeably depending on convenience and not on what might be “the best way,” if only I knew what that was. This situation was further complicated by the fact that even when asked directly which part was best for such-and-such, my more experienced friends might give different answers at different times.

After much study and experience with fresh and dried comfrey roots and leaves, I found that for most average uses—for wounds, digestive ailments, blood tonics, etc.—I got fairly equal and timely results with whatever comfrey parts were handy. The leaves have enough allantoin for many needs and since they are higher in nutritional components and tastier to most people (when needed internally) they are often the first thing I reach for in “everyday” situations. When a friend or student needs help with internal bleeding, more long-term disease conditions, or old wounds or ulcerations that seem to drag on and on without healing, I usually find the comfrey root to be what is called for as it is more potent in the allantoin department.

Comfrey leaves, both fresh and dried, are an extremely potent food source for humans and foraging animals. Years ago I discovered an excellent source book, which contained detailed information about the use, nutritional value, and cultivation of comfrey—Comfier: Food, Fodder & Remedy, by Lawrence D. Hills. Although this book is now out of print, it is well worth searching for a copy through a public or university library. Also, check out Herbal Pharmacy, by John Heinerman, and Natural Healing With Herbs, by Humbart Santillo further contemporary input on the uses and properties of comfrey in general.

At present, some researchers claim that comfrey may contain varying amounts of saturated pyrrolizidine alkaloids (called PA’s). The Herbal Products Association now suggests restricting the use of comfrey to external uses. For certain individuals, saturated PA’s, when taken internally, are found to be harmful to the liver, especially with long-term, daily use. However, many other medicinal-plant educators/authors/users assert that comfrey’s long-standing reputation as a unique, safe, and profoundly healing herb, speaks for itself: I am one of the latter group, and therefore, have not hesitated to include comfrey as one of my 10 Essentials.

However, I’m not “closing the book” on this question for my readers, especially since I realize there are common misconceptions regarding the different species of comfrey. In this book I am speaking strictly of the comfrey species called Symphytum offidnale. For commercial purposes, however, some companies are less accurate in their identification of the species used therefore; it is possible that certain comfrey preparations are using a species of comfrey that might contain varying amounts of the suspicious alkaloids. I recommend a cautious approach when using comfrey internally in some circumstances. (This does not apply to external uses). For children under three years, for pregnant or lactating women, or for those with a history of liver weakness or disease, I suggest using a liquid comfrey concentrate that is totally free of PA’s (thus eliminating the “PA question” altogether). This product is available from a company called “Herb Pharm.” Look for it at your local health food store, or order directly from Herb Pharm.

Comfrey Precautions

If you are not a member of any of the above “caution categories,” yet would like to include extra support for your liver during any long-term (three weeks or more), daily, internal use of comfrey, simply add an equal part of a potent liver-supporting herb, such as artichoke leaf (Cynara scolymus) or milk thistle seed (Silybum marianum) to your comfrey herb or formulation. And/or, you may want to take one week off of comfrey use for every three weeks of daily, internal use.

Growing Comfrey

If you would like to grow your own comfrey, yet are unsure of what species of comfrey you have acquired, or its alkaloid content, remember that comfrey root is much higher in alkaloids than the comfrey leaf, and that young leaves contain more alkaloids than older leaves. Also keep in mind that not all alkaloids in comfrey are being criticized, and only then in specific species for certain, sensitive individuals. In using comfrey leaves as a food, the alkaloids are quite water-soluble. When comfrey leaves are boiled, the vast majority of any alkaloid content in the leaves is removed into the water and this can be thrown away after cooking, especially for sensitive individuals.

Reprinted with permission from 10 Essential Herbs: Everyone’s Handbook to Health by Lalitha Thomas and published by One World Press, 2011. Buy this book from our store: 10 Essential Herbs.

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