The government is letting the study go on while the probe continues.
The $30 million study, with 1,500 participants so far in more than 100 sites around the country, is testing high doses of vitamin and mineral supplements and chelation, a treatment used for lead poisoning that has not been proved safe or effective for heart disease.
Researchers suspended enrollment last August, when the government started investigating a complaint by a group of scientists that people in the study were not being fully informed of risks and adequately protected.
Chelation involves intravenous doses of a drug, in this case disodium EDTA. Proponents claim it can flush out calcium that has built up in artery walls. Stiff or clogged arteries can lead to heart problems.
The federal Food and Drug Administration, leading doctor groups and others have called chelation experimental and of unknown value or risk for heart disease patients.
The study is sponsored by the National Heart, Lung and Blood Institute and the National Center for Complementary and Alternative Medicine.
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