Comfrey has been used since 400 BC internally (and eaten as a vegetable) until I think one research experiment with rats that ate 3-4 times its body weight for a long period of time determined it was dangerous.
One website says:
"When taken internally, comfrey can cause severe liver damage. Several studies have shown that comfrey contains toxic compounds called pyrrolizidine alkaloids or PAs, which can cause severe liver damage. Animal studies have also shown that these chemicals lead to the development of liver tumors."
Here is what she said:
"Every time I mention comfrey, someone asks if it isn't "unsafe." When I identify with comfrey, I feel like a persecuted witch wrongly accused of evil-doing. Comfrey has so much to offer as an aid to health and healing. How did such a wonderful green ally come to have such a terrible reputation?
Perhaps it starts with confusion, aided by imprecise language. There are two species of comfrey: wild comfrey, Symphytum officinale, and cultivated comfrey, Symphytum uplandica x. (The "x" means it is a hybrid, a cross.)Wild comfrey (S. off.) is a small plant--up to a meter tall--with yellow flowers. Cultivated comfrey (S. uplandica x.) is a large plant--often surpassing two meters--with blue or purple flowers.
Everyone I know grows uplandica and that is what is sold in stores. But gardeners and herbal sellers alike usually mislabel it, causing no end of confusion.
To complicate the situation even more: the roots and the leaves of comfrey contain different constituents. Comfrey roots, like most perennial roots, contain poisons. Wild comfrey (officinale) leaves have some of the same poisons. But cultivated comfrey (uplandica) leaves don't.
How can I be so sure that cultivated comfrey is safe to consume internally? Three things have convinced me.
• One: An herbal group that I belong to sent three samples of comfrey leaf (one from the west coast, one from the east coast, and one from the Rocky Mountains) to a lab to be tested for the problematic alkaloids; they found none.
• Two: During the second World War, an Englishman named Henry Doubleday devoted himself to hybridizing comfrey and making it safe to eat as a cooked green. His crosses--sterile hybrids that don't produce seeds--are what we grow in our gardens. And several generations of comfrey-eaters at his research station have no comfrey-related health problems.
• Three: I have drunk a quart or more of comfrey infusion once or twice a week for twenty years with no problems.
Drinking comfrey infusion has benefitted me in many ways: It keeps my bones strong and flexible. (An old country name for comfrey is "knit bone.") It strengthens my digestion and elimination. It keeps my lungs and respiratory tract healthy. It keeps my face wrinkle-free and my skin and scalp supple. And, please don't forget, comfrey contains special proteins needed for the formation of short-term memory cells.
the Art of Cindy Thorrington Haggerty - Comfrey leaves are not only rich in proteins, they are a great source of folic acid, many vitamins, and every mineral and trace mineral we need for a strong immune system, a calm nervous system, and a happy hormone system. See why I'm so fond of comfrey? What a marvelous ally she is! Not dangerous at all.
When I identify with comfrey, I feel powerful and proud, beautiful and exuberant. When I identify with comfrey, I feel the flexibly that comes from being knit together. When I identify with comfrey, I feel very green."
So, what I'm thinking here is that I'd like to get some comfrey tested to
1 - see how many pyrrolizidine alkaloids are really in the comfrey that I have which is bocking #4 I think - whatever Coe's Comfrey sells and
2 - see what the livers of chickens look like after eating comfrey for a few months (but not 3-4 times their body weight!) Would love to know if it really is ok to use with chickens, goats, cattle etc since that seems to cause confusion on the internet too.
3 - see if it really does cause cancer
4 - see if it causes liver issues (I just have a feeling it would clean my liver)
Anyone know how to do this research? Where to go? How much it would cost?
I'm certainly not a scientist so I wouldn't be able to do it myself (and I am in a community (track housing) that doesn't allow me to raise chickens)
Maybe we can get some permies pooling money to finally get this sorted out!
1) You do not have to be a scientist to conduct the experiment yourself. DIY Bio is a global network of like minded individuals devoted to bringing science to the public. The way most DIY Bio labs work is that one pays a membership fee, and they are then allowed to conduct their own experiments in the lab and use the equipment on site.