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      • What is the Gerson diet?
      • How well does the Gerson diet work?
      • Is the Gerson diet safe?
      • Gerson diet conclusions
    • Green tea for prevention
    • Lacto-ovo vegetarian diet
    • Megamin
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• Prevalence of CAM use

How well does the Gerson diet work?

Overall, the treatment has not been found to be effective as a cure for cancer. However, 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 (ref 5). One study conducted in 1983 did manage to track 21 patients over a five-year period, finding all but one (who was not cancer free) to be dead at the end of the study period (ref 10). However, due to not obtaining detailed medical records at the start of this study this research is not very substantive.

Since the 1940s several attempts have been made to assess the efficacy of the Gerson therapy. In 1947 the NCI (National Cancer Institute) received case studies of ten people from Gerson. The NCI reviewed the data and found no evidence to support Gerson’s claims of the therapy being effective (ref 11). The 50 cases presented in Gerson’s 1958 book (ref 12) 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 (ref 13).

In 1989, Reed et al. visited the Gerson clinic to evaluate the efficacy of the therapy on behalf of a British medical insurance company (ref 14). 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, these were sampled from all the patients treated at the clinic since starting in 1977 (this represented only a small sample of the thousands of patients treated in the 12 years). 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. There was some difficulty in assessing the efficacy of the Gerson therapy as the majority of these 27 cases had been given mainstream treatment alongside or before taking on the Gerson approach, therefore any recovery could not be causally related to the Gerson therapy. The second study by Reed et al (ref 14) collected data from 15 patients concerning their psychological state while undergoing the therapy. The researchers found a marked enhancement of pain control without the need for opiates, which were previously relied upon, and quality of life was enhanced. Patients experienced feelings of being in control and levels of high mood and confidence. The investigators concluded that the therapy offered a significant subjective benefit to the patients, and, that perhaps the active involvement of the patient in their own treatment may be a need not satisfied by current mainstream therapies. However, it must be noted that no firm conclusions can be drawn from this observational study due to the small number of participants.

One published review of the therapy found that the theoretical rationale behind the Gerson therapy does not stand up to scrutiny (ref 15). This author suggests that the "poisons" Gerson claimed to be present in processed foods are not present; that coffee enemas do not facilitate the removal of poisons from the liver; there is no evidence that the toxins Gerson refers to are the cause of cancer, and, lastly that the "healing" inflammatory reaction seen with the Gerson therapy does not promote cancer cells to be targeted and killed. However, in terms of Green’s assertion that "poisons" are not present in processed food, more recent research shows that such foods do contain harmful substances (ref 16). Furthermore, it has been demonstrated that environmental toxins play a role in the initiation of cancer (ref 17). Members of the Gerson Research Organisation (an organisation in support of the Gerson therapy which aims to conduct and publish the results of public interest research into the role of diet and nutrition) have strongly rebuked this attack on the theories of the therapy (ref 18). Here, these authors reinforced the theoretical models of how coffee enemas are believed to stimulate the release of toxins, however, they do not present any experimental evidence involving patients on the Gerson therapy to back up their claims instead they cite animal evidence (ref 19). Furthermore, Hildenbrand and Lechner (ref 18) emphasise the importance of coffee enemas in pain reduction.

Members of the Gerson Research Organisation and Cancer Prevention and Control Programme have published a five-year survival rate study of 153 cancer patients undergoing Gerson therapy (ref 20). This study found higher survival rates in patients with melanoma, colorectal and ovarian cancers undergoing the Gerson regime than for patients undergoing other therapies. However, this work has been criticised as being seriously methodologically flawed (ref 21). 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. The study’s authors themselves admit that it is only a retrospective review, rather than the preferred randomised control trial. In addition, perhaps it could be argued that it would have been better for the research to have been performed by scientists independent from the Gerson Research Organisation. Therefore, with the poor methodology, this single study does not provide conclusive support for the efficacy of the Gerson therapy.

Lastly, Ernst and Cassileth’s review of the evidence for the Gerson diet found that no convincing data exists (ref 22). The NCI (ref 23) and ACS (American Cancer Society) (ref 24) urge 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.

References

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

10. 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.

11. U.S. 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.

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

13. 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.

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

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

16. Levi, F, Pasche, C, Lucchini, F, Bosetti, C, & La Vecchia, C. Processed meat and the risk of selected digestive tract and laryngeal neoplasms in Switzerland. Annals of Oncology. 2004; 15(2):346-9.

17. Kandiloris, DC, Goletsos, GA, Nikolopoulos, TP, Ferekidis, EA, Tsomis, AS, & Adamopoulos, GK. Effect of subclinical lead intoxication on laryngeal cancer. British Journal of Clinical Practice. 1997; 51(2): 69-70.

18. Hildenbrand, GLG, & Lechner, P. A reply to Saul Green's critique of the rationale for cancer treatment with coffee enemas and diet: cafestol derived from beverage coffee increases bile production in rats; and coffee enemas and diet ameliorate human cancer pain in stages I and II. Townsend Letter for Doctors. 1994; 05.

19. Lam, LKT, Sparnins, VL & Wattenberg, LW. Effects of Derivatives of Kahweol and Cafestol on the Activity of Glutathione S-Transferase in Mice. J Med Chem. 1987; 30(8):1399-1403.

20. 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.

21. Ernst, E. The Desktop Guide to Complementary and Alternative Medicine: An Evidence-Based Approach, Mosby, London; 2001.

22. Ernst, E & Cassileth, BR. The prevalence of complementary/alternative medicine in cancer: a systematic review. Cancer 1998; 83(4): 777-82.

23. Cancer Facts. The Gerson Therapy [online]. 2004 [cited 2004 Aug 28]. Available from: URL:http://www.cancer.gov/

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