The National Institutes of Health (NIH) sponsors many controlled, clinical trials to test the value of lifestyle measures, drugs, and devices that have been shown to have health benefits in preliminary studies. Though costly, these trials are often the only way to determine whether a possible treatment is worthwhile.

In 2002, The NIH's National Center for Complementary and Alternative Medicine (NCCAM), disregarded this usual approach — of testing only those clinical measures already shown to have promise — when it approved the $30 million Trial to Assess Chelation Therapy (TACT), to see if chelation could prevent coronary heart disease (CHD).

NCCAM succumbed to pressure from a small group of complementary and alternative medicine (CAM) physicians, as well as from a powerful ally in the U.S. Congress, to approve TACT. The trial was approved even though 1) no credible evidence demonstrates any benefits from chelation therapy, and 2) in several previous controlled trials the therapy failed to improve symptoms due to atherosclerotic changes in the arteries supplying blood to the heart or extremities.

TACT is particularly galling to me because around 2001 I participated in an NIH scientific review committee that rejected a similar chelation proposal. In spite of the rejection of that proposal, TACT was later approved and started in multiple centers in 2003; it is scheduled to conclude in 2009.

Chelation therapy consists of about 30 intravenous infusions of disodium EDTA, an agent that tightly binds (chelates) blood calcium and heavy metals like zinc. These treatments cost a total of about $5,000 and are not covered by insurance.

Originally, the proponents of this form of treatment argued that chelation worked by removing calcium from the arterial plaques that narrow blood vessels. When the plausibility of that theory was debunked, chelation practitioners devised a new hypothesis of why the treatment is of benefit: EDTA binds to and carries away harmful heavy metals found in the body.

Advocates of chelation and other questionable therapies formed an organization, now named the American College for Advancement in Medicine, and continue to promote chelation therapy through publications in their own journal. These articles claim that chelation dramatically improves symptoms of CHD and prolongs life in 80 to 90 percent of patients.

I have found that these articles either describe trials that are poorly designed and conducted or that are uncontrolled "studies" purporting to show benefits from chelation therapy. In many ways, these "studies" are similar to the testimonials of individuals in advertisements for weight-loss supplements.

NCCAM was established by an act of Congress in 1998 for a worthwhile purpose: to educate the general public and physicians about complementary and alternative approaches to medicine like homeopathy and to fund research on potentially more worthwhile CAM topics such as acupuncture and herbal and other dietary supplements.

And so I am discouraged to read now that NCCAM has knuckled under to outside pressure groups and has funded a trial of a therapeutic approach that not only lacks credible supporting evidence but has already been discredited in previous controlled trials.

It is noteworthy that the chelationists have repudiated the negative results of earlier controlled trials and have continued to reap the monetary rewards of administrating chelation treatments. It is highly unlikely that TACT will show any benefits of chelation — and highly likely that the chelation therapists will continue to ignore the negative reports.