What is Essiac tea and can it cure cancer?

Essiac tea has been touted as a cure but what does the evidence show?

What if I told you that I have a secret mix of roots and herbs passed down from an ancient tribe that, when combined into a tea called Essiac, could cure you of cancer? How much would you be willing to pay?

These are the claims made about the natural cancer treatment known as Essiac tea. Essiac tea is not a new home remedy. It was developed by a nurse in the 1920s who claimed the recipe came from a Native American tribe and could be used to treat different types of cancer. Yet Essiac is still sold today, available on the shelves of health food stores and online from numerous retailers. So what exactly is Essiac tea, and what evidence is there for the claims behind it?

How Essiac tea really got its name

Essiac tea is a blend of four roots and herbs—burdock root, slippery elm bark, sheep sorrel, and Indian rhubarb root—with various other combinations of herbs added depending on the recipe. Separately, these ingredients have been touted for all sorts of benefits, including immune-boosting and antioxidant properties. 

The tea was popularized by Rene Caisse, a Canadian nurse who claims she received the recipe from a patient in the 1920s who said it cured her breast cancer. The patient also said the tea was based on a traditional medicine of the Ojibwa tribe but, in fact, there is no evidence that the tea was ever developed or used as a First Nations remedy or by any Native American culture. 

Caisse named the new tea “Essiac,” which is her last name spelled backwards. Eventually, she quit her job as a nurse to open her own clinic to treat cancer patients using Essiac tea. 

But there was no evidence that the treatment worked and the clinic closed in 1942.

After her initial failure, Caisse was given new opportunities to have the tea tested over the following decades. She declined most of these opportunities, but allowed the Memorial Sloan-Kettering Cancer Center to study the efficacy of Essiac on cancer in a variety of animals in the 1970s and 1980s. 

Eventually, Caisse decided to sell her recipe to a Canadian company that attempted to commercialize it as a medicine. Caisse passed away shortly thereafter. 

Today you can find forty different versions of the tea recipe online, some of which include watercress, blessed thistle, red clover, or kelp as additional ingredients. The tea is produced commercially by Flor Essence. You can read the full story of Rene Caisse and the development of her tea on their company’s website.

What does the evidence show?

Caisse believed that 80% of her patients were cured of many types of cancer. But when the Royal Cancer Commission of Canada looked into Caisse’s claims, researchers found little evidence that the tea was effective as a cancer treatment. 

Today, proponents claim Essiac tea is not only a cancer cure-all but also an immune system booster. Proponents also say it soothes irritations, reduces inflammation, cures viral disease like COVID-19, is a source of antioxidants, an antimicrobial, a detoxifier, and a way to improve overall health and wellbeing. Some websites even encourage use in children. 

Whenever a product is touted as a cure for a wide range of illnesses, be skeptical. Such broad claims are a red flag that the claims are not valid. 

There is little scientific evidence to support any of the claims for Essiac tea. Multiple studies exploring the effectiveness of the tea on cancer regression did not show meaningful results:

  • Early animal studies (mid-1970s) at Memorial Sloan Kettering Cancer Center did not show significant results. 
  • A retrospective study published in the Journal of Alternative and Complementary Medicine found no difference between the tea versus non-tea users for health-related quality or mood in breast cancer patients. 
  • A phase two clinical trial from 1977 found no effect of the tea on cancer survival. 
  • A Canadian government review of unpublished trial data determined that the tea had no effect on tumor growth or survival. 
  • Researchers at the Lawrence Livermore National Laboratory have shown in rats that Essiac tea actually promotes breast cancer tumor growth. 

To this day, there is no evidence published in a peer-reviewed scientific journal indicating any positive effects on cancer. The National Cancer Institute also affirms the tea is not an effective cancer treatment. 

Overall, testimonials for the tea are not backed by any conclusive scientific evidence. The Canadian company that bought rights to the tea was also unable to show any efficacy of the product against cancer. Because of this, Essiac tea was and still is marketed as a dietary supplement, not a cancer treatment. Supplements do not require the proof of effectiveness that medicines do.

So what’s the harm of drinking Essiac tea?

There is no evidence to support Essiac tea as a treatment for cancer or any other disease, but is there any risk to drinking it, just in case? Research shows that there are risks and negative effects of consuming Essiac tea. When there is no potential benefit, we must be extra wary of risks.

Of major concern for cancer patients, Essiac interferes with the way the body processes certain medications and other dietary supplements (see this link for details). It can block the cytochrome p450 pathway, which is important for how the liver breaks down many drugs and chemicals. This means that ingredients in Essiac tea can interfere with the body’s ability to process chemotherapy medications, leading to toxic blood levels of the drugs and more severe toxic reactions to chemotherapy.

Other studies found that consuming this supplement in high doses can result in kidney or liver damage due to high levels of oxalic acid. Drinking this tea can also cause side effects like nausea, vomiting, diarrhea, frequent urination, swollen glands, skin blemishes, flu-like symptoms, slight headaches, or disruptions in fluid balance. 

Bottom Line: Essiac isn’t a cure for cancer

When we are sick with a disease like cancer for which doctors don’t have all of the answers, a simple and cheap purported “cure” like Essiac tea can seem awfully appealing. But the easiest solutions aren’t always the best ones. Essiac may cause dangerous interactions with some types of cancer treatments, which is why it’s important to let your doctor know if you are thinking of using it or any other alternative treatment. 

Even though you cannot cure cancer with a dietary supplement like Essiac, there are many benefits to a healthy diet for cancer patients. Working with a registered dietitian can help ensure that you are eating well during treatment for cancer as well as post-cancer treatment. 

As for Essiac, while this tea may have a murky history, the evidence is clear. Essiac tea isn’t an effective treatment for cancer or any other condition, and it comes with plenty of risks.

.Danielle Penick

This guest post was written by Danielle Penick, RD. Danielle is a writer and registered dietitian who connects cancer survivors with evidence based research on nutrition and health. She is the creator of Survivors’ Table, an online resource for cancer survivors, and she is a practicing dietitian in Phoenix, AZ. For updates, you can follow Survivors’ Table on Facebook