THE BENEFITS OF THE USE OF COMFREY
IN HERBAL PREPARATIONS
CHEMICAL CONSTITUENTS OF COMFREY
IN HERBAL PREPARATIONS
CHEMICAL CONSTITUENTS OF COMFREY
COMFREY
by Sabrina G. Seitz, RN
by Sabrina G. Seitz, RN
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"Natural Healing with Herbs for a Healthier You"
Comfrey is a complicated herb, containing a large number of constituents. The Pyrrolizidine-type alkaloids (PA) have been the major topic of concern. There are 12 known PA’s in comfrey which include: symphytine, symlandine, echimidine, intermidine, lycopsamine, myoscorpine, acetyllycopsamine, acetylintermidine, lasiocarpine, heliosupine, viridiflorine, and echiumine. It also contains carbohydrates e.g. glucose and fructose in the form of Inulin, as well as the gums: arabinose, glucoronic acid, mannose, rhamnose, and xylose. Comfrey contains tannins which are substances that bind up proteins giving them astringent properties; and the Triterpenes: sitosterol, stigmasterol, steroidal saponins and isobauerenol. Other constituents include allantoin, caffeic acid, carotene, chlorogenic acid, choline, lithospermic acid, rosmarinic acid and silicic acid. The therapeutic value of comfrey is attributed to its content of allantoin, a cell proliferant, and rosmarinic acid, an anti-inflammatory agent and inhibitor of microvascular pulmonary injury. The rhizome of comfrey contains a higher percentage of allantoin in the early spring (January to March), decreasing as the plant grows. The allantoin then transfers to the young shoots and buds until the fall. Comfrey also contains an abundance of mucilage, a slimy, moist polysaccharide that works to moisten and soothe tissues.
Nutritionally, comfrey is rich in constituents. It contains sodium, potassium, calcium, chromium, cobalt, copper, magnesium, manganese, boron, zinc and iron. It is high in vegetable protein; in fact, you can get 20 times more protein from an acre of comfrey than you can from the equivalent amount of soybeans. Comfrey is one of the few plants that contain B-12 and is high in vitamin A, plus B-1, B-2, B-3, B-5, B-6, C and E. It has been considered as a potential food source for starving countries due to its protein content and is high in chlorophyll.
Unfortunately, poorly conducted laboratory studies have caused comfrey to garner a rather bad reputation. In 1993, the FDA posted a list of supplements that had associated illness and injuries and included Chaparral, comfrey, yohimbe, lobelia, germander, willow bark and Ma huang. The culprit constituent is the PA’s in comfrey, which is present in higher concentrations in the root. In 2001, the FDA and the FTC announced its intentions to take action against manufacturers who sold comfrey for internal use and promoted any health giving claims. In fact, Christopher Enterprises,Inc. and Western Botanicals, Inc. were targeted and suits were brought against them. Canada, Germany and the United Kingdom have similar laws restricting the distribution, sale and/or use of comfrey.
So what are pyrrolizidine alkaloids (PA’s) and are they as dangerous as the FDA would lead us to believe? Technically, the PA’s are not toxic in themselves. They are transformed in the liver to pyrroles which then exert their toxic effect by reacting with the proteins and DNA of the cells. If the liver retains these new toxins, it will result in chronic tissue changes. However, it is possible that the PA’s could be detoxified by the liver into a more soluble form and safely excreted by the kidneys. Also there is evidence that other metabolites may play a role in the toxic effects that have been attributed solely to PA’s.
These PA compounds are widely present in as many as 6,000 plant species. However, only about ½ of the identified PA’s are toxic. There is a great difference in the type and extent of toxicity within the various PA’s. Variations may include the stability of the toxic metabolite (pyrrole) that is produced from it, the rate at which the reactive metabolite is produced, the species and sex of the exposed subject, the dose, the route of administration and the healthy/nutritional status of the test subject. Toxicity will also depend on what plant part is being used e.g. the root, leaf, etc., the growth stage of the plant, the individual plant used and how long the plant has been stored. It is important to note that these variations place comfrey PA’s in a class with lower toxicity than the PA’s implicated in significant human poisonings. In fact, the journal “Science” published data by biochemist Bruce Ames, Ph.D., of the University of California at Berkeley, that indicates that comfrey leaf tea is less carcinogenic than an equivalent amount of beer. Cheers!
Nutritionally, comfrey is rich in constituents. It contains sodium, potassium, calcium, chromium, cobalt, copper, magnesium, manganese, boron, zinc and iron. It is high in vegetable protein; in fact, you can get 20 times more protein from an acre of comfrey than you can from the equivalent amount of soybeans. Comfrey is one of the few plants that contain B-12 and is high in vitamin A, plus B-1, B-2, B-3, B-5, B-6, C and E. It has been considered as a potential food source for starving countries due to its protein content and is high in chlorophyll.
Unfortunately, poorly conducted laboratory studies have caused comfrey to garner a rather bad reputation. In 1993, the FDA posted a list of supplements that had associated illness and injuries and included Chaparral, comfrey, yohimbe, lobelia, germander, willow bark and Ma huang. The culprit constituent is the PA’s in comfrey, which is present in higher concentrations in the root. In 2001, the FDA and the FTC announced its intentions to take action against manufacturers who sold comfrey for internal use and promoted any health giving claims. In fact, Christopher Enterprises,Inc. and Western Botanicals, Inc. were targeted and suits were brought against them. Canada, Germany and the United Kingdom have similar laws restricting the distribution, sale and/or use of comfrey.
So what are pyrrolizidine alkaloids (PA’s) and are they as dangerous as the FDA would lead us to believe? Technically, the PA’s are not toxic in themselves. They are transformed in the liver to pyrroles which then exert their toxic effect by reacting with the proteins and DNA of the cells. If the liver retains these new toxins, it will result in chronic tissue changes. However, it is possible that the PA’s could be detoxified by the liver into a more soluble form and safely excreted by the kidneys. Also there is evidence that other metabolites may play a role in the toxic effects that have been attributed solely to PA’s.
These PA compounds are widely present in as many as 6,000 plant species. However, only about ½ of the identified PA’s are toxic. There is a great difference in the type and extent of toxicity within the various PA’s. Variations may include the stability of the toxic metabolite (pyrrole) that is produced from it, the rate at which the reactive metabolite is produced, the species and sex of the exposed subject, the dose, the route of administration and the healthy/nutritional status of the test subject. Toxicity will also depend on what plant part is being used e.g. the root, leaf, etc., the growth stage of the plant, the individual plant used and how long the plant has been stored. It is important to note that these variations place comfrey PA’s in a class with lower toxicity than the PA’s implicated in significant human poisonings. In fact, the journal “Science” published data by biochemist Bruce Ames, Ph.D., of the University of California at Berkeley, that indicates that comfrey leaf tea is less carcinogenic than an equivalent amount of beer. Cheers!