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Other common
name(s): digestive enzyme therapy, pancreatic enzyme
therapy, systemic enzyme therapy, proteolytic enzyme therapy
Scientific/medical
name(s): none
Description
Enzyme therapy involves taking enzyme supplements as an
alternative form of cancer treatment. Enzymes are natural proteins that
stimulate and accelerate many biological reactions in the body.
Digestive enzymes, many of which are made in the pancreas, break down
food and help with the absorption of nutrients into the blood.
Metabolic enzymes build new cells and repair damaged ones in the blood,
tissues, and organs.
Overview
Available scientific evidence does not support claims that
enzyme supplements are effective in treating cancer.
How is it promoted for use?
Enzymes are sometimes used in mainstream medicine. For
example, the approved chemotherapy drug asparaginase is an enzyme. Some
enzymes are also used for other serious illnesses. Pancreatic enzymes
may be given to treat digestive problems resulting from removal of the
pancreas or certain diseases of the pancreas.
However, some alternative medicine practitioners claim that
digestive enzyme supplements not only relieve digestive problems, such
as ulcers and food allergies, but also strengthen the immune system,
improve circulation, ease sore throat pain, aid weight loss, and
relieve hay fever, ulcers, and rheumatoid arthritis. Proponents also
claim that certain enzymes remove a protective coating from cancer
cells, allowing white blood cells to identify and attack them.
What does it involve?
Human cells naturally produce about 10,000 different enzymes
which are essential in normal metabolism. Enzyme supplements are
extracted from animal organs and some plants such as pineapple and
papaya (see "Bromelain").
Among the most popular enzyme supplements are pancreatic enzymes, which
come from an animal pancreas.
Enzyme supplements are available in pills, capsules, and
powders. Supplements often consist of combinations of several enzymes.
Large amounts of the supplements are often taken each day. There is
currently no established safe or effective dosage.
Enzyme therapy is a part of some forms of metabolic therapy,
including Gerson therapy and the Kelley and Gonzalez programs. (For
more detailed information on these regimens, see our documents on "Gerson
Therapy" and "Metabolic
Therapy.")
What is the history behind it?
Pancreatic enzymes were reportedly first used to treat cancer
in 1902 by John Beard, a Scottish scientist. German researchers later
used enzyme therapy to treat patients with multiple sclerosis, cancer,
and viral infections. Some enzyme mixtures are still commonly used in
several European countries.
Dr. Edward Howell introduced enzyme therapy to the United
States in the 1920s. He believed that by eating raw meat, people
created an enzyme surplus in the body, which resulted in better health
and increased resistance to disease. Other practitioners have advocated
the use of enzyme therapy since then, often as part of a larger
metabolic therapy regimen. At least one enzyme preparation is currently
being studied in the United States for use along with chemotherapy in
cancer patients.
What is the evidence?
There have been no well-designed studies showing that enzyme
supplements are effective in treating cancer. Experts question whether
enzymes taken by mouth can reach tumors through the bloodstream, as the
enzymes are broken down into amino acids before being absorbed in the
intestine.
Studies of enzyme supplements to ease the side effects of
cancer treatment have had mixed results. Two studies done in India
reported that side effects of radiation therapy in cancer patients
taking pancreatic enzyme supplements were less severe than in those
taking a placebo. However, these studies were not blinded, meaning
patients and their doctors knew whether they were taking the actual
enzymes. This means that the results might have been affected by the
expectation of improvement, or placebo effect. A blinded German study
in which patients did not know whether they were taking the enzymes or
placebo pills did not find any benefit.
Several studies done mainly in Eastern Europe have looked at
the possible effects of adding enzyme supplements to mainstream cancer
treatment. They have generally found that supplements may improve
quality of life and could possibly have other benefits. However, these
studies are not considered scientifically strong. They looked back in
time at patients who were already treated and were not randomized or
blinded. A randomized study of the addition of enzyme therapy to
standard chemotherapy for multiple myeloma patients is under way in the
United States.
A small study of patients with pancreatic
cancer—conducted by Dr. Nicholas Gonzalez and published in
Nutrition and Cancer in 1999—found that patients treated with
pancreatic enzymes survived longer than typical patients with
pancreatic cancer. However, in a recent review of alternative cancer
therapies, an expert in integrative oncology research methods noted
that, "The study was small and obviously prone to several biases. Not
only is the comparison with national averages unadjusted for
confounders, but the principal results are based on patient selection;
twelve patients who did not comply with treatment were excluded from
analysis." Well-designed scientific studies control or adjust for
confounders, factors besides the method being studied—such as
age or cancer stage—that can affect outcome. They have a
control group that receives the standard treatment alone, and they
generally also include patients who did not complete treatment in the
final analysis.
A randomized clinical trial has been sponsored by the National
Cancer Institute to evaluate the Gonzalez regimen for treating
pancreatic cancer, but no results of this trial have yet been published
in a peer-reviewed medical journal.
Are there any possible problems or
complications?
This product is sold as a
dietary supplement in the United States. Unlike drugs (which must be
tested before being allowed to be sold), the companies that make
supplements are not required to prove to the Food and Drug
Administration that their supplements are safe or effective, as long as
they don't claim the supplements can prevent, treat, or cure any
specific disease.
Some such products may not
contain the amount of the herb or substance that is written on the
label, and some may include other substances (contaminants). Actual
amounts per dose may vary between brands or even between different
batches of the same brand.
Most such
supplements have not been tested to find out if they interact with
medicines, foods, or other herbs and supplements. Even though some
reports of interactions and harmful effects may be published, full
studies of interactions and effects are not often available. Because of
these limitations, any information on ill effects and interactions
below should be considered incomplete.
There is very little information available on the safety of
enzyme supplements. Some manufacturers recommend that people taking
blood-thinning medications speak with their doctors before taking
enzyme supplements.
Care should be taken to make sure that any diet containing raw
meat or juices from raw meat is free from bacterial contamination,
especially for people with weak immune systems.
Some people are allergic to the materials from which the
enzymes are made. Be sure to know the source of any enzymes you are
considering.
Women who are pregnant or breast-feeding should speak with
their doctor before using this method. Relying on this type of
treatment alone and avoiding or delaying conventional medical care for
cancer, may have serious health consequences.
Additional Resources
More information from your American Cancer
Society
The following information on complementary and alternative
therapies may also be helpful to you. These materials may be found on
our Web site (www.cancer.org)
or ordered from our toll-free number (1-800-ACS-2345).
References
Cassileth B. The
Alternative Medicine Handbook. New York, NY: W. W. Norton
& Co; 1998.
Dale PS, Tamhankar CP, George D, Daftary GV. Co-medication
with hydrolytic enzymes in radiation therapy of uterine cervix:
evidence of the reduction of acute side effects. Cancer Chemother Pharmacol.
2001 Jul;47 Suppl:S29-34.
Ernst E. Complementary therapies in palliative cancer care. Cancer. 2001 Jun
1;91(11):2181-5.
Gonzalez NJ, Isaacs LL. Evaluation of pancreatic proteolytic
enzyme treatment of adenocarcinoma of the pancreas, with nutrition and
detoxification support. Nutr
Cancer. 1999;33:117-124.
Green S. Nicholas Gonzalez treatment for cancer: Gland
extracts, coffee enemas, vitamin megadoses, and diets. Scientific Rev
Alt Med. 1998;2(2):25-30. Revised April 2000. Accessed at:
www.quackwatch.org/01QuackeryRelatedTopics/Cancer/kg.html on June 11,
2008.
Gujral MS, Patnaik PM, Kaul R, Parikh HK, Conradt C, Tamhankar
CP, Daftary GV. Efficacy of hydrolytic enzymes in preventing radiation
therapy-induced side effects in patients with head and neck cancers. Cancer Chemother Pharmacol.
2001 Jul;47 Suppl:S23-28.
Martin T, Uhder K, Kurek R, Roeddiger S, Schneider L, Vogt HG,
Heyd R, Zamboglou N. Does prophylactic treatment with proteolytic
enzymes reduce acute toxicity of adjuvant pelvic irradiation? Results
of a double-blind randomized trial.
Radiother Oncol. 2002 Oct;65(1):17-22.
Memorial Sloan Kettering Cancer Center. Proteolytic Enzyme
Therapy. Accessed at: http://www.mskcc.org/mskcc/html/69342.cfm on June
11, 2008.
Sakalova A, Bock PR, Dedik L, Hanisch J, Schiess W, Gazova S,
Chabronova I, Holomanova D, Mistrik M, Hrubisko M. Retrolective cohort
study of an additive therapy with an oral enzyme preparation in
patients with multiple myeloma. Cancer
Chemother Pharmacol. 2001 Jul;47 Suppl:S38-44.
Vickers A. Alternative cancer cures: "unproven" or "disproven"? CA Cancer J Clin.
2004;54(2):110-8.
Note: This information may not cover
all possible claims, uses, actions, precautions, side effects or
interactions. It is not intended as medical advice, and should not be
relied upon as a substitute for consultation with your doctor, who is
familiar with your medical situation.
Last Medical Review: 11/01/2008
Last Revised: 11/01/2008
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