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| Dong Quai and Cancer |
Answered by: Conrad Richter
Question from: Jean Bahlow
Posted on: January 29, 1999
A research paper was recently put out by the Pharmacist’s Newsletter stating that Dong Qui may have potential carcenogenic side effects. Is this true? If so where can I find the most recent research on this product? If not, where can I find informaiton refuting this statement?
Thank you for faxing me the page from the "Pharmacist’s Letter" with the warning about dong quai (Angelica polymorpha sinensis). The "Pharmacist’s Letter" appears to be a digest of news for pharmacists and the issue in question contained the warning:
"Warn women NOT to take dong quai. It can cause photosensitivity...and the oil contains a carcinogenic substance." (Vol. 14, No. 6, June 1998)
This, to me, is duplicitous in nature and probably plain wrong. All of the members of the Angelica genus have varying amounts of photoactive compounds that can cause photodermatitis in some sensitive individuals, but the offending compounds are only found in the fresh leaves, not in the roots, as far as I know. As for the "carcinogenic substance" in the oil, this again is probably referring to compounds in the fresh leaves, not the roots.
Many members of the parsley family, of which dong quai is one, have potentially carcinogenic substances in the fresh leaves. The risk however appears to be mostly theoretical because few herbs from this family are known to be carcinogenic despite years of use. Dong quai is one of the most widely used Chinese herbs, with a history of use going back at least 1000 years.
In fact, the roots are cited as having *anti-cancer* effects. Jonathan Hartwell, in his book "Plants Used Against Cancer" (Quarterman Publications) cites references from the Chinese literature that suggest that dong quai may have some effect against breast, stomach, and uterine cancer, as well as nasopharyngeal, thyroid and lymph node cancers.
John Boik in his textbook on "Cancer & Natural Medicine" refers to a variety of studies that show a possible rational basis for dong quai’s anticancer activity. For example, animal studies in which animals were injected with polysaccharides from dong quai survived fibrosarcoma longer. Other studies suggest some role in changing platelet aggregation and vascular permability which could play a role in an anticancer or antitumour effect.
The Botanical Safety Handbook put out by the American Herbal Products Association has nothing about any carcinogenic effect. You might want to contact the AHPA for their take on the report in the "Pharmacist’s Letter."
Of course, virually every food and plant product contains suspected and known tumour and cancer causing compounds the real questions are always: how much of the offending compounds are present and are the concentrations significant; is the uptake of the compounds significant; and are there other compounds that mitigate any possible danger.
To follow further research developments on this topic you can access the Medline database at http://www.nlm.nih.gov and get abtracts of relevant research and clinical papers (except for the most recent ones published in the past few months which are not yet in the database).
By the way, the "Pharmacist’s Letter" also says that "there’s NOT much evidence" that dong quai is effective as a women’s tonic. This too is probably wrong. There are is plenty of evidence that shows that dong quai has a potent regulating effect on the uterus. According to Kee Chang Huang in his book, "The Pharmacology of Chinese Herbs" (CRC Press), dong quai contains "two components... which exert either a stimulating or an inhibiting effect on the uterus. The water soluable and nonvolatile component causes stimulation, while the alcohol soluble componenet, which is an essential oil with a high boiling point, exerts the pharmacological action of inhibiting or relaxing the uterus." Western medicine often has a hard time understanding herbs that have contradictory effects such as those of dong quai, but we believe that it is precisely because of such opposing but non-cancelling effects that make herbs such as dong quai such good regulators. Western medicine is fixated on finding drugs with a one way punch which solve one problem but can cause new problems. Dong quai and other herbs promote balance, stimulating or relaxing as necessary without causing the system to "overshoot" and develop new problems.