This cancer information summary provides an overview of the use of Essiac and Flor Essence, which are proprietary herbal tea mixtures, as treatments for people with cancer. The summary includes a brief history of the development of Essiac and Flor Essence; a review of laboratory, animal, and human studies; and possible side effects associated with Essiac and Flor Essence use.
This summary contains the following key information:
Many of the medical and scientific terms used in the summary are hypertext linked (at first use in each section) to the
Reference citations in some PDQ cancer information summaries may include links to external websites that are operated by individuals or organizations for the purpose of marketing or advocating the use of specific treatments or products. These reference citations are included for informational purposes only. Their inclusion should not be viewed as an endorsement of the content of the websites, or of any treatment or product, by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board or the National Cancer Institute.
Essiac and Flor Essence are proprietary herbal tea mixtures produced by different manufacturers. Essiac is reported to contain four herbs: burdock root (Arctium lappa L.), Indian rhubarb root (Rheum palmatum L., sometimes known as Turkish rhubarb), sheep sorrel (Rumex acetosella L.), and the inner bark of slippery elm (Ulmus fulva Michx. [synonym Ulmus rubra]).[
The manufacturers of Essiac and Flor Essence both claim they market the original herbal mixture promoted by the developer.[
Essiac and Flor Essence are said to detoxify the body and strengthen the immune system.[
Although the use of Essiac and Flor Essence is generally associated with cancer treatment, both products have been used to treat other health conditions. Essiac has reportedly been used to control diabetes and to treat acquired immunodeficiency syndrome.[
Essiac and Flor Essence are sold worldwide as health tonics or herbal dietary supplements.[
To conduct clinical drug research in the United States, researchers must file an Investigational New Drug (IND) application with the FDA. An IND application must also be made for clinical evaluation of dietary supplements as agents for the treatment or prevention of disease. The FDA's IND process is confidential, and the existence of an IND application can be disclosed only by the applicants. No investigator has announced filing an IND application to study either Essiac or Flor Essence in the treatment of patients with cancer.
Essiac and Flor Essence are administered orally in the form of herbal teas.[
Only minimal information about dose and schedule of administration is freely available from the manufacturer of Essiac.[
The manufacturer of Flor Essence states that adults may consume from 30 to 360 mL (i.e., 1–12 fl oz) of Flor Essence tea per day, depending on individual requirements, and that it may be used continuously.[
The manufacturers of Essiac and Flor Essence both state these products can be used in conjunction with other cancer treatments.[
References:
Essiac was popularized in Canada during the 1920s, when the developer, a nurse from Ontario, began to advocate its use as a cancer treatment. In 1922, the developer obtained an herbal tea formula from a female breast cancer patient who claimed the mixture had cured her disease.[
From 1934 to 1942, the developer operated a cancer clinic in Bracebridge, Ontario, and dispensed Essiac free of charge.[
From 1959 until the late 1970s, the developer collaborated with an American physician to conduct clinical and laboratory studies of Essiac and to promote its use.[
In 1977, the developer provided a four-herb recipe for Essiac to a Canadian corporation.[
In the early 1980s, the Canadian Department of National Health and Welfare (Bureau of Human Prescription Drugs) conducted a retrospective review of case summaries submitted by physicians whose patients had obtained Essiac under the Emergency Drug Release Program.[
Also in the 1980s, the manufacturers of Essiac-like products began to market their formulations as health tonics and to avoid making claims of effectiveness in treating disease. Consequently, the mixtures were no longer subject to regulation as drugs. Essiac is not currently available under Canada's Emergency Drug Release Program.
In 1995, the corporation that acquired the four-herb recipe for Essiac from the developer dissolved voluntarily.[
References:
Essiac
In 2004, a mixture of the Essiac herbs showed a decreased proliferation in a prostate cancer cell line.[
In the mid-1970s, the developer submitted both dried and liquid samples of Essiac to the Memorial Sloan Kettering Cancer Center (MSKCC) in New York City for evaluation of its immunotherapeutic and chemotherapeutic potential.[
In the early 1980s, the corporation that acquired the four-herb recipe for Essiac from the developer submitted another sample to the MSKCC for evaluation in additional animal studies. No anticancer activity was detected in 17 separate experiments that utilized a variety of animal leukemia and tumor models.[
In 1983, the National Cancer Institute tested a liquid sample of Essiac that was provided by the manufacturer after the Canadian Department of National Health and Welfare (Health Protection Branch) requested that it be tested in animals.[
Flor Essence
There are conflicting results in the peer-reviewed literature. One study suggests that Flor Essence enhances tumor growth in vitro, a finding that contradicts the widely available anecdotal evidence that this product suppresses or inhibits tumor development.[
The 2004 in vivo study of Flor Essence in a rat model looked at mammary tumor development following administration of the herbal compound. Sprague-Dawley rats (N = 112) were assigned to one of three groups. The control group (n = 35) received water only. The second group (n = 40) received 3% Flor Essence in their drinking water in an attempt to provide a dose equivalent to that recommended in the popular literature. The third group (n = 37) received 6% Flor Essence in their drinking water to investigate the dose-response relationship. Mammary tumors were induced by a 40 mg/kg of body weight dose of 7,12-dimethylbenz(a)anthracene. At 19 weeks, palpable mammary tumor incidence was higher (65% and 59.4%) in both Flor Essence groups, compared with controls (51%). Terminal necropsy was performed at age 23 weeks or when tumor burden became too great. Results showed mammary tumor incidence was 82.5% for controls, compared with 90% and 97.3%, respectively, for rats consuming 3% and 6% Flor Essence.[
The Individual Herbs of Essiac and Flor Essence
Laboratory and animal experiments have shown that some of the chemicals in the herbs used to make Essiac and Flor Essence have antioxidant, anti-inflammatory, estrogenic, or anticancer activity.[
Among the herbs used in both mixtures, burdock root (Arctium lappa L.) contains several flavonoids and polyphenols that have shown antioxidant activity; Indian rhubarb root (Rheum palmatum L.) contains several anthraquinones, including emodin and aloe-emodin, which have demonstrated anti-inflammatory and cytotoxic effects; sheep sorrel (Rumex acetosella L.) contains several types of anthraquinones, including emodin and aloe-emodin, as well as phytoestrogens, which may possess both procancer and anticancer activity; and slippery elm bark (Ulmus fulva Michx.) has been shown to contain antioxidants.[
Among the herbs found in Flor Essence alone, watercress (Nasturtium officinale R.Br.) contains phenethyl isothiocyanate (PEITC), which has shown cytotoxic and antitumor activities; blessed thistle (Cnicus benedictus L.) contains cnicin, which is a sesquiterpene lactone that has demonstrated cytotoxic, antitumor, and anti-inflammatory effects, and arctiin and arctigenin, which are lignans that have shown anticancer activity; red clover (Trifolium pratense L.) contains a complex mixture of phytoestrogens, including genistein, which has demonstrated antiangiogenic, estrogenic, and procancer and anticancer effects (depending on the dose); and extracts of kelp (Laminaria digitata [Hudson] Lamx.) have shown immunostimulatory and antitumor activities.[
Whether equivalent concentrations of relevant molecules can be achieved in the bloodstream of individuals who consume Essiac or Flor Essence in the amounts recommended by their manufacturers has not been determined. An uncharacterized Flor Essence commercial product was dosed at amounts lower than those recommended by the manufacturers for humans, and there was an increase in tumor incidence in this model.[
References:
Essiac
No report of a clinical study of Essiac has been published in the peer-reviewed scientific literature. Brief descriptions of one incomplete clinical study and one retrospective evaluation of Essiac as a treatment for cancer have been published.[
As noted previously, the developer provided a four-herb recipe for Essiac to a Canadian corporation in 1977.[
In the early 1980s, the Canadian Department of National Health and Welfare (Bureau of Human Prescription Drugs) conducted a retrospective review of data voluntarily submitted by physicians for 86 cancer patients who had obtained Essiac under Canada's Emergency Drug Release Program between 1978 and 1982.[
A brief case study was published on a patient with prostate cancer who began drinking Essiac tea after experiencing a rising prostate-specific antigen (PSA) level despite hormonal therapy.[
Flor Essence
No results of human studies of Flor Essence have been reported anecdotally or in the peer-reviewed scientific literature.
References:
Nausea and vomiting are the only reported adverse effects associated with the use of Essiac.[
References:
To assist readers in evaluating the results of human/clinical studies of integrative, alternative, and complementary therapies for cancer, a scoring system has been devised that allows studies of individual treatments to be ranked according to the strength of their evidence (i.e., their level of evidence). Not all studies, however, are given a level of evidence score. To be eligible, a study must:
Evidence from studies that do not meet these requirements is considered extremely weak. In addition to scoring individual studies, an overall level of evidence assessment is usually made.
Because no study of the use of Essiac or Flor Essence in humans has been reported in a peer-reviewed scientific journal, no level-of-evidence analysis is possible for these mixtures. The data that are available, however, do not support claims that Essiac and Flor Essence can detoxify the body, strengthen the immune system, or fight cancer. At this time, evidence does not support the use of either Essiac or Flor Essence in the treatment of cancer patients outside the context of well-designed clinical trials.
Separate levels-of-evidence scores are assigned to qualifying human studies on the basis of statistical strength of the study design and scientific strength of the treatment outcomes (i.e., endpoints) measured. The resulting two scores are then combined to produce an overall score. For additional information about levels of evidence analysis, see
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Revised
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Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the use of Essiac/Flor Essence in the treatment of people with cancer. It is intended as a resource to inform and assist clinicians in the care of their patients. It does not provide formal guidelines or recommendations for making health care decisions.
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Levels of Evidence
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PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. PDQ Essiac/Flor Essence. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at:
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Last Revised: 2024-04-05
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