Chelation is a chemical process in which a substance is used to bind molecules, such as metals or minerals, and hold them tightly so that they can be removed from a system, such as the body. In medicine, chelation has been scientifically proven to rid the body of excess or toxic metals. For example, a person who has lead poisoning may be given chelation therapy in order to bind and remove excess lead from the body before it can cause damage.

In the case of EDTA, EDTA chelation therapy, the substance that binds and removes metals and minerals is EDTA (ethylene diamine tetra-acetic acid), a synthetic, or man-made, amino acid that is delivered intravenously (through the veins). EDTA was first used in the 1940s for the treatment of heavy metal poisoning. EDTA chelation removes heavy metals and minerals from the blood, such as lead, iron, copper, and calcium, and is approved by the U.S. Food and Drug Administration (FDA) for use in treating lead poisoning and toxicity from other heavy metals. Although it is not approved by the FDA to treat CAD, some physicians and alternative medicine practitioners have recommended EDTA chelation as a way to treat this disorder.

2. Does EDTA chelation therapy have side effects?

When used as approved by the FDA (at the appropriate dose and infusion rate) for treatment of heavy metal poisoning, chelation with EDTA has a low occurrence of side effects. The most common side effect is a burning sensation experienced at the site where the EDTA is delivered into the veins. Rare side effects can include fever, hypotension (a sudden drop in blood pressure), hypocalcemia (abnormally low calcium levels in the blood), headache, nausea, vomiting, and bone marrow depression (meaning that blood cell counts fall). Injury to the kidneys has been reported with EDTA chelation therapy, but it is rare. Other serious side effects can occur if EDTA is not administered by a trained health professional.

3. How might EDTA chelation therapy work to clear blocked arteries?

Several theories have been suggested by those who recommend this form of treatment. One theory suggests that EDTA chelation might work by directly removing calcium found in fatty plaques that block the arteries, causing the plaques to break up. Another is that the process of chelation may stimulate the release of a hormone that in turn causes calcium to be removed from the plaques or causes a lowering of cholesterol levels. A third theory is that EDTA chelation therapy may work by reducing the damaging effects of oxygen ions (oxidative stress) on the walls of the blood vessels. Reducing oxidative stress could reduce inflammation in the arteries and improve blood vessel function. None of these theories has been well tested in scientific studies.

4. Is there evidence that EDTA chelation therapy works for CAD?

There is a lack of adequate prior research to verify EDTA chelation therapy's safety and effectiveness for CAD. The bulk of the evidence supporting the use of EDTA chelation therapy is in the form of case reports and case series. Some patients who have undergone chelation therapy and the physicians who prescribed it claim improvement in CAD. In addition, there are approximately 12 published descriptive studies and 5 randomized controlled clinical trials regarding the use of EDTA chelation for CAD. Although each descriptive study did report a reduction in angina, they were uncontrolled clinical observations or retrospective data, typically with a small number of participants. Of the five clinical trials in which patients were randomly selected to receive chelation therapy or a placebo (a dummy solution), the most rigorous way of assessing a new treatment, three trials involved so few people that only a dramatic improvement could have been detected. Studies need a larger number of participants to detect more mild benefits of a treatment. The fourth study was never published in final form, so its conclusions are uncertain. Finally, the fifth study reported that EDTA chelation was associated with an improvement in ability to exercise, but it had only 10 participants.

5. How frequently is EDTA chelation therapy used?

It is estimated by the American College for Advancement in Medicine, a professional association that supports the use of chelation therapy, that more than 800,000 visits for chelation therapy were made in the United States in 1997 alone.