In the 1920s when essiac tea first emerged, it created a sensation as the ‘miracle’ tea which could cure cancer. Popularised by a Canadian nurse named Rene Caisse who claimed that it came from a native medicine man, the tea created an immediate buzz. The name Essiac is actually Cassie spelled backward. Indeed, it is still considered a popular treatment in alternative medicine. However, the benefits of essiac tea as a cancer cure are not validated by scientific research.
This not to say that it has no benefits. The various components of essiac tea can stimulate the immune system, reduce free radical activity, eliminate inflammation, prevent tumor growth, reduce cellular mutation, and detoxify the body. However, it is its efficacy in treating cancer that appears inconclusive. The extensive research into its anticancer properties seems to contradict itself. A research report published in the Journal of Ethnopharmacology revealed that essiac tea had potent antioxidant qualities and is very effective in DNA-protective activity. Another research paper showed that it could inhibit tumor cell growth while boosting the immune response to antigenic stimulation.  
However, a comparative evaluation of essiac did not find any significant antiproliferative effects on prostate cancer cells. A study published in Breast Cancer Research and Treatment contradicted essiac’s ability to treat cancer. It was found to stimulate the in vitro growth of breast cancer cells, indicating that it may not be beneficial for all cancer patients.  
History Of Essiac Tea Research
When it first started to gain ground, essiac created such a sensation that the Canadian government decided to investigate its scientific validity, holding public hearings in the late 30s. Subsequently, The Memorial Sloan Kettering Cancer Center carried out animal research into the benefits of the tea, followed by Resperin Corporation Ltd., which acquired the Essiac name. However, neither of the studies saw completion with concerns raised over the preparation of the formula.
The Memorial Sloan Kettering Cancer Center website today points out the contradictory studies published on the effectiveness of essiac tea. When listing its purported uses, the website reveals that there is a lack of scientific evidence to back claims of essiac’s effectiveness against cancer, HIV, AIDS and as a tonic. 
Ingredients in Essiac Tea & Their Benefits
Many of the benefits attributed to essiac tea can be traced to its constituent herbs. Essiac tea is composed of sheep sorrel, burdock root, Indian rhubarb root and the inner bark of the slippery elm. Each of these ingredients contributes to different health benefits and active ingredients, such as flavones, tannins, and anthraquinones, as well as polysaccharides that further boost the immune system.
Rumex acetosella or sheep sorrel is a common ingredient in French cuisine. Its uses range from home remedies to stain removal. According to the American Botanical Council, it is full of vitamins and minerals, such as sodium, calcium, iron potassium, magnesium, vitamin A, and C. Research published by the journal Molecules found that the flowers of sorrel have phenolic compounds that help us fight cancer through their antiproliferative effects and ability to arrest tumors. Even at low concentrations, the phenolic compounds in these flowers can prohibit cell proliferation substantially.  
Burdock root (Arctium lappa) contains Sesquiterpenes, pyridine & quinoline alkaloids. A study published in the journal Inflammopharmacology found that burdock roots were packed with beneficial compounds that can help in the management of chronic diseases like cancer, AIDS and diabetes.
Indian Rhubarb Root
A 2018 animal study published in The Journal of Pharmacy and Pharmacology on Indian rhubarb root by researchers in Egypt showed that it may reduce the progression of cancer cells in the liver. The researchers concluded that the root has the potential to be used in the treatment of hepatocellular carcinoma, recommending further clinical trials with humans.
Slippery Elm (Inner Bark)
The Native-Americans used slippery elm to treat diarrhea, cough, and diseases of the gastrointestinal tract. It is also believed to contain anti-inflammatory and antioxidant properties. 
Essiac Tea Benefits
Essiac tea gets the most attention because of its reputation as an anti-cancer herb. While this may not be conclusive, it does have other benefits. Published online in 2018, the PDQ Cancer Information Summaries, a comprehensive, evidence-based, peer-reviewed, review of essiac for health professionals agreed that while there was no research-backed data to show the tea’s anti-cancer power, its individual herbs could indeed be beneficial for our health. 
- Inflammation: Antioxidant compounds found in sheep sorrel and burdock root also have anti-inflammatory properties that can help people suffering from arthritis, headaches, gout, heart disease, joint disorders, muscle aches, hemorrhoids and a range of other common inflammatory issues. 
- Digestion: A 2018 study published in the Journal of Alternative and Complementary Medicine explored the prebiotic potential of slippery elm. The herb was found to be beneficial for modulating the gut microbiota. This could improve colon function, reduce inflammations, and protect from infections. 
- Antioxidant: As the PDQ review points out, the herbs used in essiac formulation have strong antioxidant properties. Burdock root contains flavonoids and polyphenols, while the Indian rhubarb root and sheep sorrel are rich in anthraquinones, including emodin and aloe-emodin. These have shown anti-inflammatory and cytotoxic effects.
- Respiratory Issues: Slippery elm was used by native Americans for its medicinal properties, particularly as a cough suppressant and for soothing a sore throat. 
Essiac Tea Ingredients
The classic recipe for essiac tea includes sheep sorrel, burdock root, Indian rhubarb root, and slippery elm bark. While the exact composition of the original tea seems uncertain, there have been a number of variations on the formula in recent decades. There are more than 40 essiac-like products available in North America today. The most popular “improvement” on Rene Caisse’s formula is called Flor Essence and adds four additional herbs to the mix – watercress, blessed thistle, red clover, and kelp. These additional components are claimed to improve the anti-cancer effects of this herbal health tonic. However, these claims remain equally inconclusive.
Essiac is not recognized as a medicine by the FDA. It is sold worldwide as a herbal supplement. Since these are not strictly regulated by the FDA, the purity and safety of the formulation can vary. It is always recommended to take advise from a healthcare professional before taking herbal supplements, especially if one is taking other medications.
The side-effects of essiac are not very well-researched. Most safety warnings are based on research into its constituent herbs. According to Susan G komen foundation, one of the largest breast cancer foundations in the US, side effects include diarrhea, intestinal cramping, and anticholinergic reactions. Caution is advised for people with diabetes, pregnant, and breastfeeding women. The exact formulation of essiac can also vary from one brand to another. It is advisable to check the composition and look out for any other additions.