Chelation therapy
Chelation therapy is a medical procedure that involves the administration of chelating agents to remove heavy metals from the body. Chelation therapy has a long history of use in clinical toxicology and remains in use for some very specific medical treatments, although it is administered under very careful medical supervision due to various inherent risks, including the mobilization of mercury and other metals through the brain and other parts of the body by the use of weak chelating agents that unbind with metals before elimination, exacerbating existing damage. To avoid mobilization, some practitioners of chelation use strong chelators, such as selenium, taken at low doses over a long period of time.
Chelation therapy also has a history of fraudulent use in alternative medicine, to treat claimed effects of heavy-metal exposure on problems as disparate as heart disease, cancer, and autism.
Chelation therapy must be administered with care as it has a number of possible side effects, including death. In response to increasing use of chelation therapy as alternative medicine and in circumstances in which the therapy should not be used in conventional medicine, various health organizations have confirmed that medical evidence does not support the effectiveness of chelation therapy for any purpose other than the treatment of heavy metal poisoning. Over-the-counter chelation products are not approved for sale in the United States.
Medical uses
Chelation therapy is the preferred medical treatment for metal poisoning, including acute mercury, iron, arsenic, lead, uranium, plutonium and other forms of toxic metal poisoning. The chelating agent may be administered intravenously, intramuscularly, or orally, depending on the agent and the type of poisoning.Chelating agents
There are a variety of common chelating agents with differing affinities for different metals, physical characteristics, and biological mechanism of action. For the most common forms of heavy metal intoxication - lead, arsenic, or mercury - a number of chelating agents are available. Dimercaptosuccinic acid has been recommended by poison control centers around the world for the treatment of lead poisoning in children. Other chelating agents, such as 2,3-dimercaptopropanesulfonic acid and alpha lipoic acid, are used in conventional and alternative medicine. Some common chelating agents are ethylenediaminetetraacetic acid, 2,3-dimercaptopropanesulfonic acid, and thiamine tetrahydrofurfuryl disulfide. Calcium-disodium EDTA and DMSA are only approved for the removal of lead by the Food and Drug Administration while DMPS and TTFD are not approved by the FDA. These drugs bind to heavy metals in the body and prevent them from binding to other agents. They are then excreted from the body. The chelating process also removes vital nutrients such as vitamins C and E, therefore these must be supplemented.The German Environmental Agency listed DMSA and DMPS as the two most useful and safe chelating agents available.
| Chelator | Used in |
| Ethylenediaminetetraacetic acid |
|
| Dimercaprol | |
| Dimercaptosuccinic acid | |
| Dimercapto-propane sulfonate | |
| Penicillamine | Mainly in:
|
| Ethylenediamine tetraacetic acid | |
| Deferoxamine, Deferasirox and Deferiprone |
Side effects
Chelation therapy, used to remove toxic metals such as lead, arsenic, or mercury from the body, carries a range of potential side effects. When administered appropriately under medical supervision, side effects may include dehydration, hypocalcemia, renal impairment, elevated liver enzymes, electrolytes imbalances, and allergic reactions. The loss of essential dietary elements such as zinc, magnesium, and iron is common, especially with prolonged therapy, potentially leading to fatigue, weakened immunity, or neurological disturbances.In contrast, inappropriate or non-medical use for example, in unapproved treatments for autism or cardiovascular disease - has been associated with serious complications, including severe hypocalcemia, neurodevelopmental disorders, and even death. Notably, disodium EDTA had been linked to fatal outcome when used incorrectly, such as through rapid IV administration.For these reasons, regulating authorities like FDA, CDC strongly discourage off label or unsupervised use of chelation agents.
| usage context | Potential side effects |
| Appropriate Use |
|
| Inappropriate Use |
Use in alternative medicine
In alternative medicine, some practitioners claim chelation therapy can treat a variety of ailments, including heart disease and autism.There has been scientific evidence that chelation therapy for heart disease is modestly successful. However, there is no proof that chelation therapy is effective for behavioral disorders such as autism. Chelation therapy prior to heavy metal testing can artificially raise urinary heavy metal concentrations and lead to inappropriate and unnecessary treatment. The American College of Medical Toxicology and the American Academy of Clinical Toxicology warn the public that chelating drugs used in chelation therapy may have serious side effects, including liver and kidney damage, blood pressure changes, allergies and in some cases even death of the patient.
Cancer
The American Cancer Society says of chelation therapy: "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."Cardiovascular disease
Chelation therapy for heart disease began in the 1950s after anecdotal reports that people treated with chelation for heavy metal poisoning had experienced an unexpected relief from symptoms of angina. In the 1980s-2000s, its practitioners estimated that between 100,000 and 200,000 Americans per year were undergoing chelation therapy for heart disease, at a cost of about $5,000 per course of treatment.The American College of Cardiology and the Mayo Clinic do not currently endorse chelation therapy for heart disease. However, a large-scale clinical study published in 2012 did find a modest benefit from chelation therapy in improving outcomes for patients with a prior heart attack.
In the 1990s and early 2000s, the weight of scientific evidence was against any benefit of chelation therapy for heart disease.
In 1998, the U.S. Federal Trade Commission even charged a chelation-advocacy group, the so-called American College for Advancement in Medicine, with making false or unsubstantiated claims when they promoted chelation therapy for heart disease on their website and on a brochure they published. In December 1998, the FTC announced that it had secured a consent agreement barring ACAM from making claims that chelation therapy is effective against atherosclerosis or any other disease of the circulatory system.
However, in 2003-2012, the National Institutes of Health sponsored a $30 million controlled trial of chelation therapy, conducted by their National Center for Complementary and Alternative Medicine. This was known as the Trial to Assess Chelation Therapy or TACT. In contrast to prior controlled studies that had produced negative findings, the TACT trial found that chelation therapy modestly improves outcomes for patients with a prior heart attack or history of heart attacks, and markedly improves outcomes if the patients were also diabetic.
In the leadup to the TACT trial, NCCAM Director Stephen E. Straus cited the "widespread use of chelation therapy in lieu of established therapies, the lack of adequate prior research to verify its safety and effectiveness, and the overall impact of coronary artery disease" as factors motivating the trial.
Patient enrollment was to be completed around July 2009 with final completion around July 2010,
but enrollment in the trial was voluntarily suspended by organizers in September 2008 after the U.S. government's Office for Human Research Protections began investigating complaints such as inadequate informed consent.
At the time of suspension, the trial was criticized for other methodological flaws, including being conducted by "fringe" clinicians, and lacking prior Phase I and II studies. The same critics claimed that previous controlled trials "found no evidence that chelation is superior to placebo for treatment of CAD or PVD ," making the trial "unethical, dangerous, pointless, and wasteful." Evidence of insurance fraud and other felony convictions among investigators further undermined the credibility of the trial. However, the American College of Cardiology supported the trial.
The final results of the TACT trial were published in November 2012. The study enrolled 1708 patients who were in stable condition, at least 50 years old, and had had a prior heart attack. The patients were divided into two groups, receiving chelation therapy by infusions of disodium EDTA, or receiving normal recommended therapy including statins and aspirin. The study found an 18% reduction in heart events in the patients receiving chelation therapy. And in patients with diabetes mellitus, there was a 41% reduction in clinical events, including a 43% reduction in deaths over 5 years. However, the results barely achieved statistical significance.
An editorial published in the Journal of the American Medical Association said that "the study findings may provide novel hypotheses that merit further evaluation to help understand the pathophysiology of secondary prevention of vascular disease." Critics of the study characterized it as showing no support for the use of chelation therapy in coronary heart disease, particularly the claims that chelation reduces the need for coronary bypass surgeries.
After the TACT study, further controlled studies in 2015-2022 concluded with cautious endorsements of chelation therapy for heart disease, particularly in patients with diabetes mellitus and prior heart attacks. However, an attempt to replicate the results of the TACT trial in diabetics with prior heart attacks failed to find any benefit.