What Is Essiac Tea?
Essiac is an herbal mixture, mainly administered as tea, which has been promoted as a cure for cancer for nearly a century. Clinical studies show that Essiac doesn’t cure cancer, and it may even promote the growth of certain types of cancer.
The herbal ingredients of Essiac tea include:
- Burdock root
Slippery elm bark
Reports of a cancer-curing tea originating in the forests of Ontario, Canada, surfaced in the 1920s. The tea’s ingredients remained secret for decades. Canadian nurse Rene M. Caisse held the only recipe, and she protected it until just before her death.
Caisse said the herbal recipe came from an English miner’s wife. The wife claimed a Native American healer from Ontario had cured her of breast cancer with the tea 20 years earlier. Caisse named the tea Essiac (the reverse spelling of her last name) and reportedly gave it to cancer patients for free.
Not only are its origins and healing properties steeped in mystery, Essiac is also linked to federal restrictions on its use, a report of toxicity and a death.
Despite lack of clinical evidence, thousands of people with cancer consume Essiac hoping it will help them reach remission. A survey from 2000 found 15% of Canadian women with breast cancer use Essiac. In 2006, a separate U.S. survey of 5,051 Essiac users found 22% had breast cancer.
The research conducted on Essiac in humans hasn’t held much clout in scientific communities.
Results of human studies completed in the 1970s were kept hidden. Some studies of the effect of Essiac on cancer cells in test tubes or in animals have been published, but no peer-reviewed journal has published any clinical trial of Essiac in humans. No research involving Essiac has been conducted on people with mesothelioma, either.
Caisse alleges she observed an 80% survival rate among all cancers with Essiac treatment. This claim has never been backed by records or scientific study.
What Are the Side Effects of Essiac Tea?
Side effects of Essiac tea include skin problems, nausea and vomiting. The tea’s manufacturers don’t recommend its use in pregnant or nursing women.
Increased bowel movements
Heart block (arrhythmia)
A 2022 case report published in Heart Rhythm described a patient diagnosed with a complete heart block caused by drinking a homemade version of Essiac tea containing burdock root, sheep sorrel, Indian rhubarb root and slippery elm bark.
A detailed review of the tea’s ingredients and nutritional value found it high in potassium, which was determined to be the cause of the patient’s complete heart block. The patient required a pacemaker to fix the block.
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What Drugs Interact with Essiac?
Drugs such as birth control pills, diabetic drugs and even chemotherapy may interact with Essiac tea. Make sure you talk to your doctor if you currently take or plan to take medications before ingesting Essiac tea.
- Diuretic drugs
Birth control pills
Hormone replacement drugs
Drugs that affect the kidneys and liver
DX-8951f (experimental chemotherapy drug)
Cancer Research on Essiac
Scientific research on Essiac has yielded mixed results, but the consensus is clear that it cannot cure cancer.
All human clinical trials were either stopped by government authorities or kept hidden from the public. An unpublished 1977 report of a Phase II clinical study of Essiac in cancer patients found the tea did not affect survival or shrink tumors.
Nonhuman studies have found evidence that Essiac both slows and promotes the growth of different cancers, according to a 2005 National Cancer Institute review of Essiac research. Some studies found Essiac had no positive or negative impact on cancer.
- Mid-1970s: A study conducted by Memorial Sloan Kettering Cancer Center (MSKCC) tested Essiac on mice with cancer. It found Essiac did not boost the immune system or impact cancer growth.
1980s: MSKCC continued testing Essiac on animals with cancer. They conducted 17 studies in the 1980s and found no anti-cancer effect with Essiac.
1983: The National Cancer Institute tested Essiac in mice with leukemia and found no anti-cancer effect. High doses of Essiac killed test animals in this study.
2004: In a study published in Oncology Reports, Essiac slowed the growth of certain leukemia and breast cancer cells in test tubes.
2004: Another 2004 study published in The Journal of Alternative and Complementary Medicine reported Essiac slowed prostate cancer cell growth in test tubes.
2006: A study published in Breast Cancer Research and Treatment showed Essiac stimulates breast cancer growth.
2007: A study published in Nutrition and Cancer found Essiac had no effect on prostate cancer cells.
Research on the Individual Ingredients in Essiac
Research conducted on the herbs in Essiac show they have compounds that protect DNA from damage and can influence the immune system, but they also have the potential to promote cancer growth.
- Roots of burdock and rhubarb have shown anti-cancer effects in test tube and rat studies. But these roots also contain carcinogenic compounds that cause and promote cancer.
A 2008 Chinese study published in Lung Cancer showed rhubarb extract significantly reduced pulmonary toxicity and improved lung function among lung cancer patients receiving radiation therapy.
Slippery elm bark contains mucilage, a gelatinous substance that may relieve coughs and throat irritation. It may offer relief to pleural mesothelioma patients coping with pulmonary symptoms.
In 2007, Anticancer Research published a Canadian study that was conducted in a lab with no human test subjects. It revealed Essiac contains more antioxidant properties than red wine or green tea. No antibacterial effects were observed. But Essiac did stimulate several immune system cells and enzymes.
The National Institute for Occupational Safety and Health examined the antioxidant power of Essiac in a 2006 study that was published in the Journal of Ethnopharmacology. The study found Essiac protected DNA from free-radical damage. This DNA-protective effect won’t repair damage that already led to cancer, but it could have a preventative effect with long-term use.
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Claims of Essiac as a Cancer Cure Are Anecdotal
The claims that Essiac cures cancer are anecdotal, meaning self-reported and not proven by scientific research. Clinical studies have not found evidence that Essiac can cure cancer. But research has found it high in antioxidants.
- A 2006 study published in the Journal of Ethnopharmacology shows Essiac contains antioxidants that protect against DNA damage. Antioxidants also help to counteract the effects of aging and exposure to carcinogens such as asbestos.
A 2007 study published in Anticancer Research reported Essiac has greater antioxidant properties than red wine, green tea and cocoa.
Overall, scientific research has confirmed Essiac’s antioxidant power and presented no evidence it can cure cancer.
In 2009, the U.S. Food and Drug Administration cited a brand of Essiac tea on a list of fake cancer cures that consumers should avoid.
The FDA has not approved Essiac or Flor-Essence to treat cancer or any other medical condition. Companies sell Essiac and Flor-Essence as herbal dietary supplements, which the FDA does not regulate.
Secret Recipe Blocked Research
The origins of the recipe are debated because several of the herbs are not indigenous to North America and reportedly hadn’t yet made it to the Americas through trade routes when Caisse first promoted the tea.
Originally, Caisse brewed three of the herbs into a tea and injected the other herb intramuscularly. No one but Caisse knew which herbs were brewed and which one was injected.
The secrecy of the recipe and preparation became a road block to scientific research and a source of controversy in later investigations.
Clinic Closed by Canadian Government
Caisse provided Essiac to cancer patients at the Bracebridge Cancer Clinic in Ontario starting in 1935. Evidence of a reported death and one report of toxicity caused the Cancer Commission of Canada to investigate the clinic in 1938. Although the Canadian government closed the clinic in 1941, Cassie continued to provide Essiac to cancer patients from her home.
Unpublished Clinical Trials
During the 1960s and 1970s, Caisse worked with American physician Dr. Charles Armao Brusch to modify the Essiac recipe and promote its use. Brusch also served as President John F. Kennedy’s personal doctor.
Brusch and Caisse performed clinical and laboratory studies, but they never published the results. They expanded the recipe with four additional herbs: Blessed thistle, kelp, red clover and watercress.
The pair named the new blend Flor-Essence. This new formula contained the formerly injected herb. With its inclusion, Caisse stopped providing injections.
Secret Recipe Sold
In 1977, a year before her death, Caisse sold the original, four-ingredient recipe for Essiac to a Canadian corporation. That company filed a preclinical new drug submission with the Canadian Department of National Health and Welfare.
The company received approval and began clinical studies of Essiac in cancer patients. But in 1982, the Canadian government learned the study wasn’t being conducted as planned and stopped the research.
The secret Essiac recipe was sold again, this time to Essiac Products Inc., which currently makes and sells a variety of Essiac supplements.
Flor-Essence is manufactured in British Columbia, and Brusch was reportedly involved in its production before his death. Today, several companies manufacture more than 40 different Essiac formulas and sell them worldwide.
Be Cautious of Unfounded Claims
Some promoters of Essiac make unfounded claims that it should not be taken alongside conventional cancer treatments such as chemotherapy. This promotes Essiac as an alternative medicine rather than a complementary therapy, which could have a negative impact on patient outcomes.
If cancer patients take Essiac as a first-line treatment, they run the risk of their cancer progressing to the point that conventional cancer treatment will no longer be effective.
Dr. Andrew Weil, a widely known supporter of natural medicine, issued a warning about Essiac.
Some Essiac promoters irresponsibly advise against chemotherapy and other conventional treatments when using the tea to help it work effectively. This is a reckless and dangerous recommendation. There is no clinical evidence that either Essiac or Flor-Essence has any anti-cancer activity. My advice? Avoid it.
Consumption of Essiac is unlikely to cause serious side effects among cancer patients when used as directed, but people with mesothelioma should get approval from their doctor before they try any herbal remedy. Report any changes in your health to your doctor after taking herbal supplements.