Bottom Line: Metabolic therapies do not treat or cure cancer and certain aspects of the treatments may be dangerous.
Cancer is caused by a combination of genetic and environmental factors. However, most people who promote metabolic therapies stress the environmental component, claiming that cancer is caused by an accumulation of toxins in the body from sources such as food additives, preservatives, pesticides, and industrial pollution. The removal of these toxins through bowel purging and a healthy diet, they claim, allows the body to heal naturally. Although diet may play a role in cancer prevention and it is true that some cancers are associated with environmental exposures, there is NO proof that a healthy diet or removal of toxins can change the course of cancer once genetic mutations have occurred. Some aspects of metabolic diets can be dangerous. For example, (1) the Gerson regimen restricts the diet to an unhealthy point and can cause nutritional deficiencies, (2) over-supplementation in such diets has led to toxicity and hospitalization, (3) animal extracts have been found to be contaminated, and (4) experimental drugs like interleukins and immunoglobulins may be used improperly. Overall, patients risk abandoning effective treatment by pursuing metabolic therapies.
Coffee enemas are used in several metabolic therapies. There are theories as to coffee enemas might aid excretion from the liver and colon, but none of them have been proven. In addition, coffee enemas can be dangerous when used repeatedly, causing electrolyte imbalances in the blood and impaired nutrient absorption.
To detoxify the body No scientific evidence supports this use.
To prevent and treat cancer Most metabolic therapies have not been evaluated by good clinical trials or have shown no survival advantage over conventional therapies in clinical trials. One exception to this is the Gonzalez therapy, which has shown controversial preliminary success in helping extend the survival of pancreatic cancer patients, but a larger clinical trial of this therapy is underway to see if this effect is consistently seen.
Cancer treatment Several sets of researchers have taken a look at the records of patients who used the Gerson and Kelley therapies to see if these therapies were effective. Neither therapy was found to be effective, especially when compared to conventional therapies. (Click here to see more information on the Gerson Therapy monograph in this database). Laetrile, an apricot seed extract which the Contreras and Manner metabolic therapies use, has been thoroughly evaluated and is not effective in treating cancer (Click here to see more information on the Laetrile monograph in this database).
The Gonzalez therapy was evaluated in eleven patients with inoperable stage II-IV pancreatic adenocarcinoma. All patients were given high doses (25-40 g) of oral pancreatic enzymes, nutritional supplements (vitamins, minerals, organ concentrates), coffee enemas, and an organic diet. None of the patients had undergone previous chemo- or radiation-therapy. Survival rates were higher than averages for conventional therapies: nine patients survived one year, five survived two years, and four survived three years. However, no placebo treatment was used for comparison, and critics of this study claimed that it only used patients with a good prognosis, accounting for their longer survival times. Gonzalez is conducting a large-scale, randomized controlled trial comparing his therapy to conventional therapy.
A group of researchers visited Dr. Ernesto Contreras' Clinica Del Mar in Tijuana, Mexico in order to follow the progress and survival of 22 patients using the Contreras therapy. This therapy includes laetrile, a modified vegan diet, proteolytic enzymes, and antioxidant supplements. The researchers did not have access to medical records and therefore had to rely on patient interviews for clinical information about the patient, creating a large source of error for this study. The average survival time was seven months, which is no better than typical survival times for patients using conventional therapies. It can be concluded that the Contreras therapy is ineffective in treating cancer.
Products use in these therapies are regulated by the FDA as dietary supplements. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. These products may not contain the labeled amount or may be contaminated. In addition, they may not have been tested for safety or effectiveness.
The American Cancer Society strongly urges cancer patients not to seek treatment with costly and potentially hazardous metabolic/nutritional therapies, including the Gerson, Manner, and Contreras regimens, in Mexican border clinics.
Excessive use of coffee enemas can cause infections, dangerous electrolyte imbalances, and death, especially when combined with fasting.
Coffee enema insertion devices should not be shared, at the risk of transferring bacteria and infection.
Nutrient deficiencies (calcium, vitamins D and B12, protein), anemia, and malabsorption
Coffee enemas: Electrolyte imbalance, which has resulted in serious infections, dehydration, colitis, constipation, and death. Hard enema insertion devices can rupture the colon.
Coffee enemas - Case reports: Two people died from electrolyte imbalances resulting in seizures, coma, and death. One was using 1-4 coffee enemas per hour for a number of days and the other used four per day for eight weeks.
Eating a balanced diet rich in fiber, fruits, and vegetables is known to be an important part of preventing disease, but there is no proof that diet or supplements can treat or cure cancer once it exists. Although controlling one's diet may create a greater sense of personal control, especially during the difficult experience of cancer therapy, the extreme restrictions of many metabolic therapies are dangerous for cancer patients because they limit sources of many important nutrients. In addition, cancer patients run the risk of abandoning effective conventional therapies if they choose to pursue alternative therapies like metabolic therapies.
Strict dietary and detoxification regimens touted to prevent and treat cancer and degenerative diseases. Metabolic therapies, offered in the U.S. and at Mexican border clinics, are based on the theory that cancer and other diseases are caused by an accumulation of toxic substances in the body. Advocates claim that a healthy diet, detoxification practices (e.g., coffee enemas, herbal laxatives), and immune augmentation detoxify the body and allow it to heal naturally. Therapies such as the Gerson, Kelley, Contreras, Manner, and Gonzalez regimens share this ideology but differ in modality. Diet is often based on whole foods and fresh fruits and vegetables, and is supplemented by digestive enzymes, glandular extracts, megadose vitamins, minerals, or herbal products. Agents such as BCG, gamma globulins, interleukins, hydrazine sulphate, hydrogen peroxide, or laetrile may also be administered. Weekly costs at Mexican border clinics are typically $3000-5000 (4). Although dietary remedies provide a strong sense of personal control, the strict dietary recommendations of some metabolic therapies can cause nutritional deficiencies, while some entail potentially toxic doses of supplements or agents. Excessive use of coffee enemas can cause sepsis, dangerous electrolyte deficiencies, and death. Retrospective reviews of the Gerson, Kelley, and Contreras metabolic therapies show no evidence of efficacy. An NCCAM-sponsored open-label trial of the Gonzalez regimen in patients with stage II-IV pancreatic adenocarcinoma is underway (6) after promising results from a small pilot study (10). The American Cancer Society strongly urges cancer patients not to seek treatment with metabolic therapies.
Advocates of metabolic therapies claim that cancer and other diseases result from an accumulation of toxins in the body from food additives, preservatives, pesticides, and industrial pollution that disrupt the immune system and cell metabolism. The removal of these toxins through bowel purging and a healthy diet, they claim, allows the body to heal naturally. Although diet may play a role in cancer prevention and some cancers are associated with environmental exposures, no evidence shows that removal of such toxins or changing the diet can impede the course of cancer once it has been established. Furthermore, strict dietary restrictions, as in the Gerson regimen, cause nutritional deficiencies. Supplements are purported to normalize metabolism, strengthen the immune system, and destroy tumors, but over-supplementation has caused toxicity requiring hospitalization. Glandular extracts are likely rendered ineffective when hydrolyzed in the gut, and animal extracts have been found to be contaminated. Experimental drugs like interleukins and immunoglobulins may be used improperly. Overall, patients risk abandoning effective treatment by pursuing metabolic therapies.
Caffeine in coffee enemas is purported to cause dilation of bile ducts, bile production, glutathione S-transferase (GST) activation, and excretion of toxic breakdown products by the liver and through the colon wall. No published evidence supports these claims and no human studies examine the clinical efficacy or physiological effects of coffee enema administration. Kahweol and cafestol are constituents of green coffee that stimulate GST activation, but their activity is destroyed with roasting. Repeated administration of coffee enemas increases extravascular fluid volume and can cause serum electrolyte imbalances. The significant loss of bile salts associated with repeated long-term administration of enemas can result in malabsorption of fat, fat-soluble vitamins, and calcium. (1)(2)(3)
The American Cancer Society strongly urges cancer patients not to seek treatment with costly and potentially hazardous metabolic/nutritional therapies, including the Gerson, Manner, and Contreras regimens, in Mexican border clinics. Excessive use of coffee enemas can cause infections, dangerous electrolyte deficiencies, and death, especially when combined with fasting. (4)
Common: Flu-like symptoms, nausea, vomiting, diarrhea, weakness, dizziness, intestinal cramping, fever, muscle aches and pains, rashes. Nutrient deficiencies (calcium, vitamins D and B12, protein), anemia, and malabsorption may result from metabolic diets (4). Reported (Coffee enemas): Electrolyte imbalance, which has resulted in serious infections (e.g., Campylobacter sepsis and amebiasis), dehydration, colitis, constipation, and death. Perforation or rupture of the colon from hard insertion devices and transfer of pathogenic microorganisms by contaminated devices are also reported (3). Case Reports (Coffee enemas): Case 1: Multiple seizures and hypokalemia leading to cardiorespiratory arrest, coma, and death were reported after excessive use of coffee enemas (1-4 per hour) for a number of days. Case 2: Death attributable to fluid and electrolyte imbalance causing pleural and pericardial effusions after use of coffee enemas, 4 per day for 8 weeks (1).
Retrospective analyses of the Gerson and Kelley therapies show no evidence of therapeutic efficacy. Laetrile, which the Contreras and Manner metabolic therapies employ, has been found ineffective in treating cancer. An NCI-sponsored open-label trial of Gonzalez's nutritional therapy versus gemcitabine in patients with stage II-IV adenocarcinoma of the pancreas is underway. (6) Gonzalez NJ, Isaacs LL. Evaluation of pancreatic proteolytic enzyme treatment of adenocarcinoma of the pancreas, with nutrition and detoxification support. Nutr Cancer 1999;33:117-24. A small, unblinded, one-arm pilot study assessing survival in 11 patients with inoperable stage II-IV pancreatic adenocarcinoma treated with high doses (25-40 g) of oral pancreatic enzymes, nutritional supplements (vitamins, minerals, organ concentrates), detoxification procedures (coffee enemas), and an organic diet. Patients had not undergone previous chemo- or radiation-therapy. Nine patients survived one year, 5 survived 2 years, and 4 had survived 3 years at time of publication. Median survival was 17 months. Results were compared to statistics from the National Cancer Data Base from 1995: 25% survival at one year and 10% survival for 2 years for all stages of pancreatic carcinoma; median survival, 6 months. A criticism of this study is that its eligibility criteria select for a subset of "good-prognosis" pancreatic cancer patients. A large-scale, randomized controlled trial comparing this nutritional therapy to gemcitabine is underway.
Austin S, Dale EB, Dekadt S. Longterm followup of cancer patients using Contreras, Hoxsey and Gerson therapies. J Naturopathic Med 1994;5:74-6. Small prospective evaluation of survival rates in advanced cancer patients at three Tijuana clinics, including Dr. Ernesto Contreras' Clinica Del Mar. Patients were interviewed at the clinic regarding location of primary tumor, presence of metastasis, and whether it was biopsy-confirmed. Most patients were unaware of the stage of their cancer, and medical records were not available for review. Patients receiving Contreras therapy (n=31), including laetrile, a modified vegan diet, proteolytic enzymes, and antioxidant supplements, were queried by mail yearly for 4-5 years or until death. Of 22 evaluable patients, mean survival time from beginning of study was 7 months. Despite the obvious flaws of this study - small sample size, majority of patients lost to follow-up, and lack of access to detailed medical records - it can be concluded that the Contreras therapy is ineffective in treating late stage cancer patients.
