Gerson therapy

The Gerson Therapy™ uses a special plant-based diet, supplements and also coffee enemas to detoxify and stimulate the body’s metabolism. Proponents of the Gerson Therapy™ have made claims that it is an effective treatment for cancer and other illnesses, through balancing the levels of potassium and sodium in the body, removal of toxins and regeneration of liver function as well as improving overall nutritional status.

Based on one methodologically flawed retrospective study and several case reports, there is no clear evidence that Gerson Therapy™ is an effective treatment for people with cancer. A small best case series review concluded that both physical and psychological benefits, appeared to be offered by this regime, but these findings have not been replicated in any acceptable trials.

Some evidence exists to suggest that elements of the therapy (coffee enemas in particular) are potentially dangerous if used excessively. In addition to this the excessive demands of time, money and other resources on the patient undergoing the therapy may be extreme. An indirect risk is that patients following Gerson Therapy™ are advised to cease conventional cancer treatments including chemo-or radiotherapy.


Mora D, Wider B, CAM-Cancer Consortium. Gerson therapy [online document], Jul 31, 2023

Document history

Assessed as up to date in July 2023 by Dana Mora, revised by Barbara Wider. Assessed as up to date in May 2020, January 2019, February 2017, April 2016, January 2015 and August 2013 by Barbara Wider. Updated and revised in September 2012, August 2011 and November 2009 by Helen Cooke. Summary first published in July 2005, authored by Helen Seers and Helen Cooke. Next update due: July 2026


The Gerson Therapy™ uses a special diet, supplements and also coffee enemas to detoxify and stimulate the body’s metabolism. It was originally devised by the German physician Dr. Max Gerson (1881-1959). After his death his daughter Charlotte Gerson (1922-2019) continued his work and founded the Gerson Gerson Institute in the USA. Worldwide, there are two licensed Gerson clinics: the «Health Institute de Tijuana» in Playas de Tijuana, Mexico and the “Gerson Health Centre” in Budapest, Hungary. To publicise the therapy as much as possible, Charlotte Gerson toured the world lecturing and providing workshops for patients and health care professionals (Gerson Institute 2023).


The Gerson diet is an entirely organic, plant-based diet. It also includes multiple glasses of juices which are prepared hourly from fresh, raw, organic fruits and vegetables. Coffee enemas are administered as the primary method of detoxification; these are claimed to eliminate wastes, regenerate the liver, reactivate the immune system and restore the body’s essential defenses – enzyme, mineral and hormone systems. (Gerson Institute 2023)

A variety of supplements may also be administered administered on the Gerson regime, these include: potassium compound, Lugol’s solution (an inorganic solution of iodine with potassium iodide), thyroid hormones, pancreatic enzymes and niacin. (Gerson Institute 2023)

Alleged indications

The Gerson Therapy™ is not targeted at any one specific symptom or disease. Its promoters claim that “by addressing the root causes of most degenerative diseases – toxicity and nutritional deficiency – the Gerson Therapy™ effectively treats a wide range of different ailments." (Gerson Institute 2023)

Mechanisms of action

The intensive treatment based on nutrition and detoxification is claimed to restore and revitalise the body, strengthen the immune, enzyme and hormone systems and correct the function of the essential organs.

According to the Gerson Institute “an abundance of nutrients from copious amounts of fresh, organic juices are consumed daily, providing the body with a super-dose of enzymes, minerals and nutrients that is easily assimilated. In addition, raw and cooked solid foods are generously consumed. These substances then break down diseased tissue in the body, while coffee enemas aid in eliminating toxins from the liver. Oxygenation is usually more than doubled, as oxygen deficiency in the blood contributes to many degenerative diseases. The metabolism is also stimulated through the addition of thyroid, potassium and other supplements, and by avoiding heavy animal fats, excess protein, sodium and other toxins.» (Gerson Institute 2023)

Application and dosage

Treatment is initially provided by Gerson clinics. Worldwide, there are two clinics licensed by the Gerson Institute: the Health Institute de Tijuana in Mexico and the Gerson Clinic Europe  in Hungary. For those unable to visit a licensed clinic or undergoing conventional treatments, the Gerson Institute offers Web-Based Case Management where practitioners certified Gerson by the Gerson Insitute provide individualized Gerson Therapy protocols online.

The Gerson Institute provides a newsletter and contact details of support groups run by long-term recovered patients. It offers a list of “Recovered Patient Referrals” to prospective new patients.

One published review of the therapy found that the theoretical rationale behind the Gerson Therapy™ does not stand up to scrutiny (Green 1992).

Prevalence of use

Reliable estimates of how many people follow the therapy worldwide are not available.

Legal issues

There are two Gerson treatment centres licensed by the Gerson Institute in the world, one in Mexico and one in Hungary. The Gerson Institute offers training to a variety of different health practitioners to enable people to become licensed Gerson Practitioners.

No controlled trials have been conducted on the Gerson Therapy™. One methodologically flawed retrospective study and several case reports are available. There is no clear evidence that Gerson Therapy™  is an effective treatment for people with cancer. A small ‘Best Case Series’ review concluded that both physical and psychological benefits, appeared to be offered by this regime, but these findings have not been replicated in any rigorous trials. Attempts to evaluate the Gerson Therapy™ as a whole are problematic due to the complexity of the treatment, time taken for its possible effectiveness and poor record keeping/tracking of previous patients by the Gerson Institute (Moss 2005).

Clinical trials

A five-year survival rate retrospective study of 153 cancer patients found higher survival rates in patients with melanoma, colorectal and ovarian cancers undergoing the Gerson regime than for patients undergoing other therapies (Lowell 1986). However, it should be noted this work was conducted by members of the Gerson Research Organisation and has been criticised as being seriously methodologically flawed (Hildenbrund 1995). This research did not use the same matched control for each of their categories studied. Furthermore, it was not performed under tightly controlled conditions assessing the other therapies that the patients may have been receiving.

Case reports/series

Since the 1940s several attempts have been made to assess the efficacy of the Gerson Therapy™. In 1947 the NCI (National Cancer Institute) reviewed case studies of ten people from Gerson and found no evidence to support Gerson’s claims of the therapy being effective (Ernst 2006). The 50 cases presented in Gerson’s 1958 book (US DoH 1987)were also reviewed by the NCI in 1959, however, it was concluded that the case histories were not presented in sufficient detail (for instance, verification of the tumour, previous treatment history) to be able to evaluate the clinical benefit of the therapy (Gerson 1999).

A preliminary study conducted in 1983 tracked down 21 patients over a five-year period and found all but one (who was not cancer free) had died at the end of the study period (Avery 1982). However, due to not obtaining detailed medical records at the start of this study this research is not very substantive.

In 1989, Reed et al. visited the Gerson clinic to evaluate the efficacy of the therapy on behalf of a British medical insurance company (Austin 1994). Two investigations were conducted and presented in one paper. The first investigation concerned how patients responded to the therapy and the other was a psychological study of the patients at the clinic. For the first investigation, the Gerson clinic presented 149 cases to the researchers. Of the 149 only 27 cases were able to be assessed as they possessed independent documentation of their disease from a mainstream physician. The researchers concluded that there was little evidence for the Gerson Therapy™ having an anti-tumour effect, instead finding only a very small amount of successful responses with three of the 27 cases showing a complete response and one patient with a stable disease result. The second study by Reed et al collected data from 15 patients concerning their psychological state while undergoing the therapy (Austin 1994). The researchers found a marked enhancement of pain control and quality of life was enhanced. However, it must be noted that no firm conclusions can be drawn from this observational study due to the small number of participants.

A 2007 case study analysis of six people with cancer who followed the Gerson Therapy™ concluded that some support, both physical and psychological, appeared to be offered by this regime (Reed 2020). The analysis reported that some potential anti-cancer effects appeared to be present in the patients who undertook this regime. The patients also had an increased sense of hope and empowerment. The authors stated however that many cofactors may have influenced these findings; some of the patients were undergoing conventional treatment, some were also using other complementary approaches. The analysis was conducted using the 'Best Case Series' criteria developed by the National Cancer Institute (Molassiotis 2007).

A 2010 overview of the Gerson regimen reported that case reviews by the National Cancer Institute (NCI) and the New York County Medical Society found no evidence of usefulness for the Gerson diet (Cassileth 2010).

There is concern that people may choose to use this regime as an alternative to chemotherapy, thereby avoiding mainstream treatment. The Gerson Institute does not recommend the use of chemotherapy with the diet since the chemotherapy is seen as a poison in the body, and during detoxification the body would find difficulty in dealing with the level of toxins1. Several aspects of the Gerson therapy itself have been seen as possible causes of adverse effects. These include: coffee enemas17, the restrictive nature of the diet, thyroid supplements and also the now disused practice of drinking liver juice. The American Cancer Society and the US National Cancer Institute, do not recommend the use of the Gerson therapy, warning that patients should not turn away from mainstream therapy to rely only on this alternative approach.

Adverse effects

Coffee enemas

Serious illnesses, colitis, electrolyte imbalance and even death have been associated with the use of coffee enemas (Eisele 1980). However, these incidences have not been reported in patients undergoing the Gerson treatment at the clinic. In two isolated cases reported two women in Seattle (one with cancer) died due to the enemas removing potassium from the body leading to serious electrolyte imbalance. In either case enemas were used more frequently than is recommended by the Gerson Therapy™ guidelines. It is thought that continued home use of enemas may weaken the colon’s natural function leading to problems such as constipation and colitis (Eisele 1980).

Restricted diet

The use of a restricted detoxifying metabolic diet alongside enemas may cause an “inflammatory reaction” which is believed to be part of the healing process (US DoH 1987). Negative symptoms of this inflammatory reaction include dehydration, nausea, diarrhoea, flu-like symptoms and death (Eisele 1980; Anonymous 1993).


There are safety concerns over the excessive ingestion of potassium. Those with too much potassium in their blood may suffer from hyperkalemia; symptoms include muscle numbness, tingling, abnormal heart rhythm, paralysis and possible heart failure (Tobian 1997).

Calves liver juice

The drinking of calves’ liver juice was removed from the Gerson Therapy™ guidelines in 1989 after a history of it being associated with infection with Campylobacter fetus subspecies fetus (Gerson Institute 1989). An outbreak of this bacterial infection was seen in 1981 which killed nine cancer patients who were thought to be using the Gerson treatment (Gerson Institute 1989; Ginsberg 1981). After learning of this outbreak staff at the Gerson Institute worked with those at the clinic in Mexico to ensure patient safety and by 1989 the policy of drinking liver juice was altered to receiving crude liver extract injections.


Due to the complex nature of the therapy many interactions with other drugs may occur.


There is concern that people may choose to use this regime as an alternative to chemotherapy, thereby avoiding mainstream treatment.  The American Cancer Society and the US National Cancer Institute, do not recommend the use of the Gerson Therapy™; the National Cancer Institute urges patients to not seek treatment from the Gerson clinic due to a lack of evidence of the anti-cancer effects and also potential hazards associated with the therapy. (NCI 2016) 

Anonymous. Questionable methods of cancer management: 'nutritional' therapies. CA Cancer J Clin. 1993; 43(5):309-19. Accessed 8th of September 2020.

Austin, S, Dale, EB, & DeKadt, S. Long-term follow-up of cancer patients using Contreras, Hoxsey and Gerson therapies. Journal of Naturopathic Medicine. 1994; 5(1):74-76

Avery, RJ, Office of Cancer Communications, National Cancer Institute, National Institutes of Health, U.S. Department of Health and Human Services, letter to G. Dego, University of London, August 24, 1982.

Cassileth B. Gerson regimen. Oncology (Williston Part) 2010; 24(20): 201.

Eisele, JW, & Reay, DT. Deaths related to coffee enemas, JAMA. 1980; 244: 1608-9.

Ernst E, Pittler MH, Wider B. The Desktop Guide to Complementary and Alternative Medicine: An Evidence-Based Approach, Mosby, London; 2006.

Gerson Health Centre, Europe. Gerson Institute Homepage [available online]. 2023. Accessed 11th of July, 2023.

Gerson Institute Homepage [available online]. 2023. Accessed 11th July, 2023.

Gerson Institute, "Raw Liver Juice Has Been Discontinued," Memo, October 3 1989.

Gerson, C & Walker, M. The Gerson Therapy. 60 years of proven success! Kensington Publishing, USA; 2001.

Gerson, M. A Cancer Therapy. Results of Fifty Cases, 6th Ed. Bonita, CA: Gerson Institute, 1999.

Ginsberg, MM, Thompson, MA, Peter CR, et al., "Campylobacter Sepsis Associated With 'Nutritional Therapy'--California," M.M.W.R. 1981; 30(24): 294-295.

Green S. A critique of the rationale for cancer treatment with coffee enemas and diet. JAMA. 1992; 268: 3224-3227. 

Health Institute de Tijuana. Gerson Institute Homepage [available online]. 2023. Accessed 11th of July, 2023.

Hildenbrand, GL, Hildenbrand, LC, Bradford, K, & Cavin, SW. Five-year survival rates of melanoma patients treated by diet therapy after the manner of Gerson: a retrospective review. Altern Ther Health Med. 1995; 1:29-37. 

Lowell, J. The Gerson Clinic. Nutrition Forum. 1986; 3(2):9-12.

Molassiotis A, Peat P. Surviving against all odds: analysis of 6 case studies of patients with cancer who followed the Gerson therapy. Integrative Cancer Therapies. [Case Reports]. 2007 Mar;6(1):80-8.

Moss RW. Patient perspectives: Tijuana cancer clinics in the post-NAFTA era. Integrative Cancer Therapies. [Historical Article]. 2005 Mar;4(1):65-86. Accessed 8th of September 2020.

NCI, National Cancer Institute. Gerson Therapy PDQ. Available online. Accessed 11th July 2023.

Reed A, James, N, & Sikora, K. Mexico: juices, coffee enemas, and cancer. Lancet, 1990; 336 (8716):677-678. 

Revill, J. Now Charles backs coffee cure for cancer, Observer, June 27 2004.

Tobian, L. Dietary sodium chloride and potassium have effects on the pathophysiology of hypertension in humans and animals. American Journal of Clinical Nutrition. 1997; 65: S606- S611.

US DoH, US Department of Health and Human Services, Public Health Service, National Institutes of Health, National Cancer Institute, National Cancer Institute Statement, "Unproven Methods: The Gerson Therapy," February 5, 1987.


Norway's National Research Center in Complementary and Alternative Medicine

We work to give you facts about complementary and alternative medicine, so that you can make safer choices for your health.

Read more about NAFKAM

Other websites from NAFKAM: