|
Other common
name(s): none
Scientific/medical
name(s): ethylene diamine tetraacetic acid (EDTA),
edetate sodium
Description
Chelation therapy is a mainstream treatment used to treat
heavy metal poisoning. However, the term is also used to promote an
alternative therapy that is supposed to treat heart disease, cancer,
and other conditions. It most often involves the injection of ethylene
diamine tetraacetic acid (EDTA), a chemical that binds, or chelates,
heavy metals, including iron, lead, mercury, cadmium, and zinc. The
term "chelation" comes from the Greek word chele, which means "claw,"
referring to the way the chemical grabs onto metals.
Overview
Chelation therapy is one of several effective treatments for
lead poisoning. However, available scientific evidence does not support
claims that it is effective for treating other conditions such as
cancer. Chelation therapy can be toxic and has the potential to cause
kidney damage, irregular heartbeat, and even death.
How is it promoted for use?
Chelation therapy using EDTA has been approved by the U.S.
Food and Drug Administration (FDA) as a treatment for lead poisoning
for more than forty years. The human body cannot break down heavy
metals, which can build up to toxic levels in the body and interfere
with normal functioning. EDTA and other chelating drugs lower the blood
levels of metals such as lead, mercury, cadmium, and zinc by attaching
to the heavy metal molecules, which helps the body remove them through
urination.
Because EDTA can reduce the amount of calcium in the
bloodstream, some practitioners suggest chelation therapy may help
reopen arteries blocked by mineral deposits, a condition called
atherosclerosis or hardening of the arteries. They claim it is an
effective and less expensive alternative to coronary bypass surgery,
angioplasty, and other techniques designed to unclog blocked arteries.
Chelation therapy has also been promoted as an alternative
treatment for many unrelated conditions, such as gangrene, thyroid
disorders, multiple sclerosis, muscular dystrophy, psoriasis, diabetes,
arthritis, Alzheimer’s disease, and the improvement of
memory, sight, hearing, and smell.
Some alternative practitioners further claim chelation therapy
can be used as a cancer treatment. They claim it can remove
"environmental toxins" from the body and block the production of
harmful molecules called free radicals that can cause cell damage.
What does it involve?
Chelation therapy is most often given into a vein, either as a
short injection or over a period of two to four hours. A typical
treatment cycle may include twenty injections or infusions spread over
ten to twelve weeks. Chelation therapy can also be given by mouth.
Practitioners recommend at least twenty to forty treatments to start;
however, some may recommend continued therapy for up to a hundred
treatments over a period of several years. Because the therapy removes
some important minerals from the body, patients often receive high-dose
vitamin and mineral supplements during treatment.
What is the history behind it?
The chemical solution most often used in chelation therapy,
EDTA, was first made in Germany in the 1930s. It is now widely accepted
as an effective treatment for heavy metal poisoning.
In the 1950s, some scientists theorized that EDTA could remove
calcium from the body. Calcium can build up on artery walls, eventually
causing heart disease, and it was theorized that use of EDTA could
unclog blocked arteries. In some early studies, researchers reported
positive results among patients with heart disease who received EDTA.
Some said that chelation therapy relieved chest pain caused by blocked
arteries. These first observations have not been confirmed by larger,
more rigorous studies, but they led some practitioners to begin using
chelation therapy for heart and circulatory problems and, later, for
several other illnesses. It is estimated that tens of thousands of
Americans currently undergo chelation therapy for heart disease.
In 1998, the Federal Trade Commission charged the American
College of Advancement in Medicine (ACAM), the principal group
promoting chelation therapy, with presenting false advertising and
unsubstantiated statements about its benefits. The ACAM agreed to stop
publishing any claims that were not based on reliable scientific
evidence.
What is the evidence?
Chelation therapy is a proven treatment for lead poisoning and
poisoning from other heavy metals. However, available scientific
evidence does not support claims that the treatment benefits patients
with cancer, heart disease, or any medical problems other than
heavy-metal poisoning.
There are no published studies that reliably show benefit from
using chelation therapy with EDTA against cancer. Some laboratory
studies have suggested that agents other than EDTA that chelate copper
or iron may affect cancer cells or the formation of tumor blood
vessels. In a small study using mice, researchers studied
iron-chelating agents to see if they would reduce the growth of
neuroblastoma, a type of cancer in infants and young children. The
results, published in 1998, concluded that chelation therapy did not
shrink tumors. Few studies of the use of chelation therapy against
cancer in humans have been published in peer-reviewed medical journals.
These few studies have been small and have not shown a significant
level of effectiveness. Research is continuing in this area. A 2006
study found that a new iron chelator called
di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone reduced growth of
skin cancer cells in mice. However, this experimental treatment has not
been tested in humans and is very different from the chelation agents
used by alternative practitioners.
Available research does not yet support claims that chelation
therapy can treat heart disease. Randomized clinical trials have found
that chelation therapy drugs did not benefit patients with impaired
circulation in their legs. In 1993, a review of all chelation therapy
studies reported during the previous 37 years concluded that scientific
data did not support claims that the treatment was useful for treating
heart problems. Studies published since then have generally reached the
same conclusion. A very large, placebo-controlled study sponsored by
the National Center for Complementary and Alternative Medicine is now
under way and should provide a more definitive answer as to whether
chelation therapy has any effects on heart disease.
According to a number of well-respected organizations,
including the American Heart Association, the American Medical
Association, the Centers for Disease Control and Prevention, the
American Osteopathic Association, the American Academy of Family
Physicians, and the FDA, there is no scientific evidence that chelation
therapy is an effective treatment for any medical condition except
heavy metal poisoning.
Are there any possible problems or
complications?
This substance
may not have been tested to find out how it interacts with medicines,
foods, or dietary 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.
Available scientific evidence does not support claims that
chelation therapy is a safe treatment for any type of cancer. Chelation
therapy may produce toxic effects, including kidney damage, irregular
heart beat, and swelling of the veins. It may also cause nausea,
vomiting, diarrhea, and temporary lowering of blood pressure. Since the
therapy removes minerals from the body, there is a risk of developing
low calcium levels (hypocalcemia) and bone damage. Chelation therapy
may also impair the immune system and decrease the body's ability to
produce insulin. People may also feel pain at the site of the EDTA
injection. Chelation therapy may be dangerous in people with kidney
disease, liver disease, or bleeding disorders. Women who are pregnant
or breastfeeding should not use this method.
Chelation therapy is often given along with large doses of
vitamins and other minerals, which may actually contribute to the
processes that produce dangerous free radicals in the body. Loss of
zinc can also lead to mutations in cells. For this reason, chelation
therapy may actually increase the risk of cancer.
The possible interactions between chelation therapy and
prescription or over-the-counter medicines are not entirely known.
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.
Ernst E, ed. The
Desktop Guide to Complementary and Alternative Medicine: An
Evidence-Based Approach. London, UK: Mosby; 2001.
Green S. Chelation therapy: Unproven claims and unsound
theories. 2002. Accessed at:
www.quackwatch.org/01QuackeryRelatedTopics/chelation.html on June 11,
2008.
Grier MT, Meyers DG. So much writing, so little science: a
review of 37 years of literature on edetate sodium chelation therapy. Ann Pharmacother.
1993;27:1504-1509.
Guldager B, Jelnes R, Jorgensen SJ, et al. EDTA treatment of
intermittent claudication: a double-blind placebo-controlled study. J Intern Med.
1992;231:261-267.
Knudtson ML, Wyse DG, Galbraith PD, Brant R, Hildebrand K,
Paterson D, Richardson D, Burkart C, Burgess E. Chelation therapy for
ischemic heart disease: a randomized controlled trial. JAMA.
2002;287(4):481-486.
MD Anderson Cancer Center. Comlementary Practice: Chelation
(EDTA) Therapy. Accessed at:
http://www.mdanderson.org/departments/cimer/display.cfm?id=4230febd-e954-4025-86affa94c7a8fc71&method=displayfull&pn=6eb86a59-ebd9-11d4-810100508b603a14
on June 21, 2008.
Redman BG, Esper P, Pan Q, Dunn RL, Hussain HK, Chenevert T,
Brewer GJ, Merajver SD. Phase II trial of tetrathiomolybdate in
patients with advanced kidney cancer. Clin Cancer Res.
2003;9(5):1666-1672.
Selig RA, White L, Gramacho C, Sterling-Levis K, Fraser IW,
Naidoo D. Failure of iron chelators to reduce tumor growth in human
neuroblastoma xenografts. Cancer
Res 1998;58:473-478.
van Rij AM, Solomon C, Packer SG, Hopkins WG. Chelation
therapy for intermittent claudication. A double-blind, randomized,
controlled trial. Circulation.
1994;90:1194-1199.
Whitnall M, Howard J, Ponka P, Richardson DR. A class of iron
chelators with a wide spectrum of potent antitumor activity that
overcomes resistance to chemotherapeutics. Proc Natl Acad Sci U S A.
2006;103:14901-14906
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
|
