Essiac and Flor-Essence

1. What are Essiac and Flor-Essence?

Essiac and Flor-Essence are herbal tea mixtures that have been used as anticancer treatments. Essiac is reported to contain 4 herbs: burdock root, Indian rhubarb root, sheep sorrel, and the inner bark of slippery elm. Flor-Essence is reported to contain the same 4 herbs found in Essiac plus 4 additional herbs: watercress, blessed thistle, red clover, and kelp. Different batches of these 2 mixtures may contain different ingredients and the effects may not always be the same.

Essiac and Flor-Essence are sold worldwide as health tonics or herbal dietary supplements. Although only one company sells Flor-Essence, several companies produce and market Essiac-like products. This summary refers to the trademarked mixtures only and differentiates between Essiac and Flor-Essence whenever possible.

2. What is the history of the discovery and use of Essiac and Flor-Essence as complementary or alternative treatments for cancer?

A nurse in Canada first began to promote Essiac as a cancer treatment in the 1920s. The nurse obtained the herbal tea formula from a breast cancer patient who said it had cured her disease. The patient reportedly received the formula from an Ontario Ojibwa Native American medicine man. In 1934, the nurse began operating a cancer clinic in Ontario and distributed Essiac free of charge. In 1938, the Royal Cancer Commission of Canada visited the clinic but found only limited evidence that Essiac was effective. The nurse closed the clinic in 1942 but continued to provide Essiac to patients until the late 1970s.

Between 1959 and the late 1970s, the nurse collaborated with an American physician to conduct clinical and laboratory studies of Essiac and to promote its use. The results of these studies were not reported in any peer-reviewed scientific journals. The 2 also developed the formula now called Flor-Essence. In 1977, the nurse provided the recipe for Essiac to a Canadian corporation. In 1978, the Canadian government gave this company permission to conduct clinical studies on the safety and effectiveness of Essiac but withdrew its permission in 1982 (see Question 5). This company also filed an unsuccessful Investigational New Drug (IND) application with the US Food and Drug Administration (FDA) (see Question 8).

In the 1980s, manufacturers of Essiac-like products began to market their preparations as health tonics. Because the manufacturers did not make claims of effectiveness in treating disease, Essiac was no longer subject to regulation as a drug.

3. What is the theory behind the claim that Essiac and Flor-Essence are useful in treating cancer?

Proponents of Essiac and Flor-Essence say that these products strengthen the immune system, have anti-inflammatory effects, and show anticancer activity because the herbs they contain are present in the correct proportions. This claim, however, has not been rigorously studied. The individual herbs in the Essiac and Flor-Essence formulas have been shown to contain molecules that have anticancer, anti-inflammatory, antioxidant, or immunostimulatory activity. Refer to the PDQ health professional summary on Essiac/Flor-Essence for more information on theory.

4. How are Essiac and Flor-Essence administered?

Essiac and Flor-Essence are administered by mouth (orally) in the form of herbal teas. According to the manufacturer, the proper dosage of Essiac depends on why a person is taking it. The manufacturer’s recommended schedules of administration assume that Essiac will be taken for 12 continuous weeks. The manufacturer of Flor-Essence states that adults may take between 30 and 360 milliliters (1 to 12 fluid ounces) of Flor-Essence tea a day, depending on individual requirements, and may take it on an ongoing basis.

The manufacturers of Essiac and Flor-Essence state that the products can be used with other therapies. Some proponents of Essiac, however, recommend that patients avoid any additional anticancer therapy (such as chemotherapy or radiation therapy) when taking Essiac because it may interfere with immune system function and prevent Essiac from working effectively.

5. Have any preclinical (laboratory or animal) studies been conducted using Essiac or Flor-Essence?

No results of laboratory or animal studies using Flor-Essence have been reported in the peer-reviewed scientific literature or in other publications. Although no reports of laboratory or animal studies using Essiac have been published in peer-reviewed scientific journals, researchers have conducted 3 animal studies with this product.
* In the mid 1970s, the Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City tested dried and liquid samples of Essiac in 8 experiments involving the S–180 mouse sarcoma tumour model (a type of animal model used to study treatment). Researchers found that Essiac did not stimulate the immune system or act as an anticancer drug.
* In the early 1980s, researchers at MSKCC tested Essiac again. They found no anticancer activity after conducting 17 experiments that used a variety of animal leukemia models and other tumour models.
* In 1983, NCI tested a liquid sample of Essiac in the mouse P388 lymphocytic leukemia tumour system but found no anticancer activity. The highest concentrations of Essiac killed the test animals. Scientists, however, do not know how this finding applies to people who take more than the recommended doses of Essiac.
* A 2004 animal study of Flor-Essence found that Flor-Essence can promote mammary tumour development in rat models of breast cancer.

6. Have any clinical trials (research studies with people) of Essiac or Flor-Essence been conducted?

No results of human studies of Flor-Essence have been reported. In addition, no reports of clinical trials (research studies) of Essiac have been reported in the peer-reviewed scientific literature. Brief descriptions of one incomplete clinical trial and one retrospective evaluation of Essiac as a cancer treatment have been published, however. (A retrospective study looks backward in time, usually using medical records and interviews with patients.)
* In 1978, the Canadian government gave permission to a Canadian company to begin studying Essiac for safety and efficacy. In 1982, the government withdrew its permission after determining that the company was not adequately controlling the manufacturing consistency of Essiac or conducting appropriate clinical trials. A review of data from this incomplete study showed no clear evidence of improved survival in cancer patients who took Essiac. Findings also showed that Essiac was not toxic.
* In the early 1980s, the Canadian government reviewed information submitted by physicians regarding 86 cancer patients who had taken Essiac. This retrospective evaluation was based on written summaries submitted by the physicians and not on a review of the original patient records. The researchers concluded that the benefits of treatment could not be clearly attributed to Essiac.

7. Have any side effects or risks been reported from Essiac or Flor-Essence?

The only reported side effects associated with Essiac are nausea and vomiting. According to the manufacturer, potential side effects of Flor-Essence include increased bowel movements, frequent urination, swollen glands, skin blemishes, flu-like symptoms, and slight headaches.

8. Is Essiac or Flor-Essence approved by the FDA for use as a cancer treatment in the United States?

The FDA has not approved Essiac or Flor-Essence as a cancer treatment or to treat any other medical condition. An IND application was filed for Essiac, but it was not successful (see Question 2).

The manufacturers market Essiac and Flor-Essence as health tonics or herbal dietary supplements, which are regulated as foods by the FDA. Essiac or Flor-Essence would have to be approved by the FDA as a drug for manufacturers to claim that the products treat or prevent a disease.