Q: My mother has severe narrowing of the arteries to her heart and legs. She has been through coronary artery bypass surgery but still gets chest pain and crampy pains in her legs when she walks more than a block. Her doctors say further surgery will not help her heart, and they have tried all sorts of medicines without any apparent improvement.
A doctor who does chelation therapy told me this type of treatment will improve blood flow to my mother's heart and legs. Would you advise chelation therapy?
A: Definitely not! Chelation therapy is unproven, unpleasant and expensive.
The usual chelation therapy consists of about 30 treatments. Each involves the intravenous administration of a chemical called EDTA (ethylenediaminetetra-acetate). In the past, proponents said that EDTA increased blood flow by finding calcium and removing it from the arteriosclerotic plaques that narrow large fTC arteries. More recently, advocates of chelation treatments have proposed that EDTA prevents the formation of oxidation products, which damage blood vessel walls.
Despite claims, however, there is no valid evidence that chelation increases blood flow or improves symptoms due to narrowing of the arteries to the heart or legs.
In fact, a clinical trial published in 1992 showed no benefit in 153 Danish patients with narrowing of the arteries to their legs.
The subjects were randomly divided into two equal groups, which received a course of 20 intravenous infusions of either EDTA or salt water (placebo). When examined three and six months after the two courses of treatment, identical numbers of subjects in both groups reported their symptoms were unchanged or improved. After treatment, there was no difference between the two groups in objective measurements of how far the subjects could walk before developing leg pains.
It is instructive to note that 50 percent of the patients treated with salt water injections (and 48 percent of those treated with EDTA) reported mild to great improvement in their symptoms -- once again demonstrating the strong "placebo effect" of any treatment and the questionable validity of claims for benefits from any therapeutic approach unless a comparison is made with some type of placebo treatment.
Proponents of chelation therapy will undoubtedly argue that the Danish study has some flaw in its design -- the number of infusions, the manner of preparing the EDTA, and so on. But the fact remains that one careful study showed no benefits of chelation treatment, while no studies have demonstrated improvements with the treatment.
I remain equally dubious of the claims, also unsupported by any valid evidence, that chelation therapy improves liver function, memory and vision, lowers cholesterol, relieves symptoms of arthritis, Parkinson's disease and multiple sclerosis, and reduces the incidence of cancer.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.