Gerson Detailed Scientific Review

Overview

Background

The Gerson program, one of the oldest Western nutritional approaches to cancer treatment, was developed by German physician Max B. Gerson (1881-1959)¹. Gerson had initially devised a diet in an attempt to relieve his own migraine headaches. During the course of prescribing the diet for other patients with migraines, he discovered that it also appeared to be effective for patients with lupus vulgaris and arthritis. In 1928, a patient with bile duct cancer and liver metastases insisted that he prescribe a diet for her. He reluctantly agreed because of her poor prognosis, but was surprised when she apparently recovered six months later¹. None of his next seven patients with cancer appeared to be helped by the diet, but others were and he continued to develop the theory and elements of the diet.

Dr. Gerson emigrated to the United States in 1938, passed his state medical board examination and began practicing and developing his treatment in New York City. He developed a reputation for helping patients and was invited to present case histories to a 1946 Congressional hearing on another subject. He presented written case histories of ten patients treated with his diet who he claimed were cured of advanced cancer. The American Medical Association (AMA) strongly criticized these presentations as being only "clinical impressions" and not "scientific evidence". At that time, diet was not accepted by mainstream medical opinion as having any role in cancer development or treatment and Dr. Gerson lost his hospital affiliation and was denied malpractice insurance¹.

His program was revived in 1976 by his daughter, Charlotte Gerson, RN, who opened a clinic in Tijuana, Mexico. Currently, the Gerson Institute, based in San Diego, California, trains clinicians for the Tijuana and other clinics². The Gerson Research Organization conducts research into the role of diet and nutrition in the management of cancer and other diseases with a focus upon the Gerson diet plus a related metabolic intervention program known as Issels therapy³. [Dr. Josef Maria Issels (1907-1997), a retired member of the German Federal Cancer Commission, became co-principal investigator with the Gerson Institute for a short time before his death⁴.].

The Gerson Therapy and Program

The Gerson theory is based upon an understanding of cancer as a process involving fermentation rather than oxidative metabolism and the ability of the body to mount a general inflammatory response to the cancer. The Gerson dietary program seeks to restore the body to its optimal functioning in order to respond to the cancer by: 1) supporting the vitality of intestinal flora through the provision of oxidative enzymes; 2) detoxifying and supporting the liver and other vital organs with daily enemas and supplements of vitamins, minerals, and thyroid hormones; 3) managing abnormal water retention in cells by restricting dietary sodium and supplementing the diet with potassium^1,5.

Accomplishing these goals is sought through a diet of fresh, organic produce year round with daily vegetable and fruit juices plus cooked vegetables, whole grains and whole fruits. These foods are supplemented with vitamin B₁₂, minerals, pancreatic enzymes and thyroid extracts when judged necessary. Dietary fat is strictly reduced and protein temporarily restricted with a vegetarian diet. Multiple daily enemas are frequently prescribed for detoxification².

Previously, patients were required to drink three glasses of fresh calves liver daily, but this was discontinued due to risks associated with raw liver^1,5. Injectable crude liver extracts rather than juice are currently included². Details of the Gerson diet have been described and compared with two other similar diets (Kelley and Modified Kelley)⁶.

Proposed Mechanism of Action

Fermentation/anaerobic metabolism of cancer cells

Gerson’s proposal of a fermentative process was based upon the theories of Otto Warburg, a respected scientist of the time. However, that theory was subsequently disproved and current Gerson practitioners no longer endorse it³.

Inflammatory response to cancer

Gerson’s proposal of killing cancer cells through a general inflammatory response has also been critiqued. Saul Green, PhD, a recognized expert in biochemistry, immunology and nutrition, notes that attempts to initiate inflammatory responses to tumors (see also Coley toxins on this website) have shown only occasional success. He also points out that inflammatory responses damage normal as well as cancerous cells⁷.

Oxidative enzymes in foods

Gerson proposed that tumor cells thrive in an environment depleted of oxygen, but can be destroyed when oxidative reactions occur that are catalyzed by oxidative enzymes. Accordingly, he promoted the concentrated intake of intact oxidative enzymes from fresh fruits and vegetable juices obtained through special (non centrifugal) juicers.

Green also critiqued this theory of oxidative damage and cited a 1961 review that provided several lines of evidence that oxygen neither prevented nor inhibited cancer growth. He then noted subsequent research concerning damage to DNA as the culprit in the initiation, promotion and progression of cancer. He also doubted that oxidative enzymes within foods could have any effect on non-digestive tissues since they would normally be broken down into their component amino acids during digestion and not pass intact through the intestinal wall. Otherwise, he asserted, they would be likely to provoke an allergic response from the host⁷.

In response, Gar Hildenbrand and Peter Lechner of the Gerson Research Organization said that they had already publicly acknowledged that the oxygen theory was out-of-date³. They also disagreed with the statement that intact proteins would necessarily provoke immune responses if they passed through the intestinal wall³.

Coffee enemas

Gerson proposed that coffee enemas would help the liver to excrete toxins because the caffeine in the coffee dilated liver bile ducts, which then absorbed toxic products (e.g. phenacetin and other free radicals) into bile which would subsequently be injected into the small intestine and then excreted. He also proposed that enemas would cause another route of excretion through direct dialysis through the colonic wall into the colon. This theory was consistent with practices of Gerson’s time and coffee enemas were endorsed as a short-term detoxification regimen by the Merck Manual as late as 1972⁵.

Bile as a vehicle for detoxification was also critiqued by Green who cited literature descriptions of 95% of bile being recirculated from the small intestine back to the liver via the portal circulation. He noted no references in the literature to bile flow being stimulated by caffeine, questioned the bioavailability of related components in roasted coffee and generally characterized the practice of enemas as a fifth century concept of purging⁷.

Hildenbrand and Lechner responded with a description of the extraction process and demonstration of stimulated bile flow in animal experiments. They also cited other contemporary investigators of enemas for decontamination after poisoning and for active Crohn’s disease. They then emphasized that Gerson had proposed the use of enemas chiefly for the relief of pain rather than curing of cancer³.

Potassium/sodium balance

Gerson proposed that the potassium/sodium balance was critical to correction of generalized tissue damage and inferred that cancer regressed faster in the presence of a higher ratio of potassium to sodium.

This potassium/sodium ratio theory was supported by some research efforts in the 1980s. A study of normal and malignant human thyroid biopsy samples reported that increasing levels of sodium in relation to potassium were associated with increasing malignancy⁸. Maintenance of the normal phenotype of rat kidney cells challenged with a sarcoma virus was associated with higher levels of potassium in a study by investigators at The University of Texas MD Anderson Cancer Center. However, the largest percentage of protected cells were in hypertonic solutions in which potassium was added to sodium rather than replacing it⁹. Geographical variations in the potassium content of ground waters were examined in relation to cancer mortality rates by another MD Anderson investigator. He reported significant associations of higher potassium levels with lower cancer mortality rates and his extensive analyses also uncovered interactions of potassium with altitude (related to oxygen air pressures), blood acid/base levels, sodium, calcium, dietary sources, genetic predisposition to hypertension and aging factors^10-13.

Other research on potassium/sodium ratios has produced conflicting results. A review by Bortner and Cidlowski of the National Institute of Environmental Health Sciences of the NIH relates the process of cell shrinkage during apoptosis (programmed cell death) to the movement of potassium ions out of and sodium ions into cells. This process has been shown to modify cellular metabolism and gene expression in liver cells and control glutamine and glucose metabolism in lymphocytes and macrophages¹⁴. Two other in vitro studies have demonstrated that inhibition of potassium channels inhibited the proliferation of human myeloblastic ML-1 cells and induced apoptosis in malignant astrocytoma cells. It was unclear whether the inhibition of potassium channels was directly involved in apoptosis or secondary to the generalized process of cell death¹⁴.

Toxicity

In Lechner and Kronberger’s matched-control study of a modified Gerson diet, four enemas per day caused three patients to develop colitis. They then reduced the number of enemas to two daily. Also in this study, thyroid supplementation was associated with severe bleeding in patients with abnormal hemostasis due to liver metastases⁵.

More information on the science and research in Gerson therapy is provided in the Summary of Research.

Summary of Research

Amount and Type of Research

A search of the PubMed, Scopus, CINAHL and Alt HealthWatch databases for “Gerson” as a keyword between 3/01/2003 and 1/31/2006 identified nine new articles, none of which were applicable to Gerson diet and cancer or its treatment. A previous search of the Medline and Alt HealthWatch databases between 10/31/97 and 1/31/03 identified 12 new articles, three of which were applicable to the Gerson diet and cancer or its treatment, but no new studies were identified. (A separate search for potassium and cancer related terms is not included in these totals.)

A review of the literature and other sources prior to 10/31/97 had identified 47 references, of which 45 (96%) were applicable to cancer. Thus, these three sets of reviews have identified 48 applicable articles of which we have retrieved 43 (91%) and classified these references in the following types of information:

Of the human related articles, we coded the studies (7*) by the following study designs:

**One article reported two studies¹⁵.
** These are not National Cancer Institute certified "best cases"; rather they are defined as "best cases" because of their selection by the author of the study from among a larger group of cases.

A total of seven human studies have been identified in the literature as of January 31, 2006. Two were matched control studies¹⁵, one was a prospective cohort study¹⁶, two were retrospective reviews with historical controls^17,18, one was a best case series¹⁹ and one was a set of case reports²⁰.

The two prospective matched control studies (reported in one article) evaluated patients with colon cancer that had metastasized to the liver and patients with breast cancer. They were started on a Gerson diet and compared with matched controls without the diet. In the colon cancer study, the average survival was longer for the Gerson subjects, but no statistics were reported to assess the significance of this difference. (Averages are not a recommended way for assessing survival differences; medians and cumulative rates are preferred.) Among breast cancer patients, no significant differences in metastases or rates of survival were reported between cases and controls¹⁵.

One study of three sets of prospective cohorts consisted of 108 patients with various histologically confirmed late-stage cancers treated with one of three therapies (Contreras, Hoxsey or Gerson) provided by three different clinics in Tijuana, Mexico. Of the 38 patients treated with the Gerson therapy, 20 were lost to follow-up, 17 died with a mean survival of nine months and one patient remained with disease at five years¹⁶.

One retrospective cohort study reported higher survival rates for patients with melanoma, colorectal and ovarian cancers than rates in the literature¹⁸, but no statistics were reported to substantiate the results. The other retrospective study¹⁷ analyzed the survival of 153 stage I through IV melanoma patients who were treated with the Gerson diet. All 14 early stage (I and II) patients were disease free at 17 years, but this number was too small for statistical comparison with other cohorts. Of the 35 stage III patients, the five-year survival rate was 71%, compared to survival rates reported in the literature of 27% to 42% (p=0.002). Of the 18 stage IV patients, the five-year survival was 39%, compared to 6% in the literature (p<0.001). Not included in this analysis were 53 patients who were lost to follow-up¹⁷. The exclusion of lost-to-follow-up could have affected these survival comparisons since standard practice would have been to include them until their last date known alive.

A best-case series of six patients "improved remarkably"¹⁹ and a set of 10 case reports had "improvements" in general body health and regression of tumor masses²⁰. A set of 17 "Gerson Recoveries" reported in a Gerson Institute booklet² can not be evaluated because this series has not been reported in the peer-reviewed literature.

Conclusions concerning the effectiveness of the Gerson therapy are not possible based upon these current studies. However, if the retrospective review of melanoma patients¹⁷ were to be reanalyzed with the lost-to-follow up patients included, it would then be more appropriate to compare their survival rates with those of other series in the literature. Similarly, a reanalysis of the two matched control studies to include median and cumulative survival rates would make comparison of those results more appropriate. For all studies of dietary therapies, an assessment of compliance with the regimen is a challenging, but necessary task.

Abbreviated study notes are provided in the Gerson Summary of Human Studies Table (pdf).

Study descriptions and sources for these data are available in the Annotated Bibliography.

Annotated Bibliography

Human Studies

¹⁵Lechner P, Kronberger J. Erfahrungen mit dem einsatz der diat-therapie in der chirurgischen onkologie. (Experience with the use of dietary therapy in surgical oncology) Akt.Ernahr-Med. 1990;15:72-78.

Purpose: Survival and disease response
Type of Study: Prospective cohort with matched controls
Methods & Results: Two studies were reported in this article:

Study #1: Patients who had carcinoma of the colon with liver metastasis (n=36) were selected from the General Surgery Department of the authors’ clinic in Austria. Patients were selected for the study if a matched control could be found. Controls were matched on age, sex, localization and stage of tumor. (Duration of diet not stated).

Results: In the diet group the mean survival was 28.6 months. For the control groups it was 16.2 months. (Statistical significance not reported.)

Study #2: Breast cancer. (n= 38) Patients were selected from the General Surgery Department of the authors’ clinic in Austria. Patients were selected for the study if a matched control could be found. Controls were matched on age, sex, localization of tumor, receptor status, menopausal status and type of adjuvant treatment (chemotherapy or radiation). (Duration of diet not stated).

Results: No significant differences were seen in terms of metastases and rates of survival between the two groups.

¹⁶Austin S, Dale EB, Dekadt S. Longterm followup of cancer patients using Contreras, Hoxsey and Gerson therapies. Journal of Naturopathic Medicine. 1994;5:74-76.

¹⁷Hildenbrand, G., Hildenbrand, L. Five-year survival rates of melanoma patients treated by diet therapy after the manner of Gerson: A retrospective review. Alternative Therapies. 1995;V1.

Purpose: Survival
Type of Study: Retrospective review with historical (literature) controls
Methods: (Superficial and nodular melanoma) Patient records were reviewed and family and friends contacted to determine the outcomes of 153 white adult patients (25-72 years) with melanoma who had begun the Gerson's Dietary Treatment. The patients had superficial and nodular melanomas and were classified into four stages of melanoma. Their survival times were compared by stage of disease with survival rates reported in the literature. For most comparisons, chi-square tests was used. When comparing small samples, Fisher's Exact Test was used. Cox regressions and log-rank tests were used for comparisons of homogeneity of survival curves. Not included in the analysis were 53 patients who were lost to follow-up.
Comment: The omission of 53 patients lost-to-follow-up could have biased the results in a direction favorable to the Gerson subjects since standard survival analysis would have included them up to the date when they were last known to be alive.
Results:

¹⁸Hildenbrand G, Hildenbrand L. Defining the role of diet therapy in complementary cancer management: prevention of recurrence vs. regression of disease. Proceedings of the 1996 Alternative Therapies . Symposium: Creating Integrated Healthcare. January 18-21, 1996 Sandiego, CA.

¹⁹Gerson M. Effects of combined dietary regimens on patients with malignant tumors. Exp Med Surg. 1949;7:299-317.

²⁰Gerson, M. Dietary considerations in malignant neoplastic diseases: A preliminary report. Rev Gastroent. 1945;12:419-425.

Note: Not included in this Annotated Bibliography is a set of 17 cases reported in the Gerson Institute literature since this series has not been separately published in peer-reviewed literature.

Reference List

1. U.S. Congressional Office of Technology Assessment. Unconventional Cancer Treatments. Washington, DC: U.S. Government Printing Office, 1990. Report No.: OTA-H-405.
2. Gerson Institute. Gerson Recoveries. San Diego, CA.
3. Hildenbrand G and Hildenbrand C. Gerson Research Organization [Web Page].
4. Hildenbrand G. An appraisal of the life and work of Dr. Josef Maria Issels. The J of Alternative and Complementary Medicine 1998;4(2):137-40.
5. Lerner M. Choices in Healing: Integrating the Best of Conventional and Complementary Approaches to Cancer. Cambridge, MA: MIT Press, 1994.
6. Holl RM. A comparison of three unconventional cancer therapies. Alternative Health Practitioner Winter97;3(4):167-76.
7. Green S. 'Antineoplastons'. An unproved cancer therapy [see comments]. [Review]. JAMA 1992 Jun;267(21):2924-8.
8. Zs.-Nagy I, Lustyik G, Lukacs G, Zs.-Nagy V, Balazs G. Correlation of malignancy with the intracellular Na+:K+ ratio in human thyroid tumors. Cancer Research 1983;43:5395-402.
9. Lai C, Becker F. Potassium induced reverse transformation of cells infected with temperature sensitive transformation mutant virus. Journal of Cellular Physiology 1985;125:259-62.
10. Jansson B. Dietary, total body and intracellular potassium/sodium ratios. Cancer Det Prev 1990;14:563-5.
11. Thompson JR, Brown BW, eds. Cancer Modeling. New York and Basel: Marcel Dekker, Inc, 1987.
12. Jansson B. Geographic cancer risk and intracellular potassium/sodium ratios. Cancer Detection and Prevention 1986;9:171-94.
13. Jansson B. Potassium, sodium, and cancer: a review. J Envir Pathology, Toxicology and Oncology 1996;15(2-4):65-73.
14. Bortner CD, Cidlowski JA. A necessary role for cell shrinkage in apoptosis. Biochem Pharmacol 1998;56(12):1549-59.
15. Lechner P, Kronberger J. Erfahrungen mit dem einsatz der diat-therapie in der chirurgischen onkologie. Akt.Ernahr-Med 1990;15:72-8.
16. 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):74-6.
17. Hildenbrand G, Hildenbrand L. Five year survival rates of melanoma patients treated by diet therapy after the manner of gerson: A retrospective review. Alternative Therapies 1995 Sep;Vol 1(4).
18. Hildenbrand G, Hildenbrand L. Defining the role of diet therapy in complementary cancer management: prevention of recurrence vs. regression of disease. Proceedings of the 1996 Alternative Therapies . Symposium: Creating Integrated Healthcare. January 18-21, 1996 Sandiego, CA.
19. Gerson M. Effects of combined dietary regimens on patients with malignant tumors. Exp Med Surg 1949;7:299-317.
20. Gerson M. Dietary considerations in malignant neoplastic disease. Rev Gastroent 1945;12:419-25.