People trying to treat their own ailments with remedies from health-food stores have become severely ill from pills and powders sold as "dietary supplements," according to six separate reports published Thursday in the New England Journal of Medicine.

Lead poisoning, impotence, lethargy, nausea, vomiting, diarrhea and abnormal heart rhythms were among the disorders described, resulting from powerful herbs, toxic contaminants or the presence of potent drugs or hormones in products that were supposed to be "all natural" and free of drugs.In addition, several children with cancer worsened when their parents rejected conventional therapy in favor of alternative methods.

The six reports - three articles and three letters to the editor - involved only about a dozen patients, but Dr. Marcia Angell, executive editor of the journal, said, "I think this is the tip of the iceberg." The six different reports reached the journal over a period of several months, Angell said, and were not solicited by the editors.

In a sharply worded editorial accompanying the reports, she and Dr. Jerome Kassirer, the editor in chief of the journal, criticized supplement makers and practitioners of alternative medicine for advocating unproven and potentially harmful treatments. "Alternative treatments should be subjected to scientific testing no less rigorous than that required for conventional treatments," they wrote.

Taken together, the editorial and multiple case studies from the medical establishment amount to a throwing down of the gauntlet before the booming supplement industry. The cases demonstrate that consumers can be harmed by seemingly innocuous herbs and nutritional supplements and lend weight to the argument that the loosely regulated industry should be held more accountable for its products.

Unlike drugs, dietary supplements do not have to be proved safe and effective before they are put on the market. Angell said that if supplements were held to the same standard as drugs, "the onus would be on the manufacturers to prove safety and efficacy, and I think most of them would shut down."

She was especially critical of the Dietary Supplement Health and Education Act of 1994, which weakened the authority of the Food and Drug Administration to regulate vitamins, herbal remedies and other products classified as dietary supplements.

Dr. Annette Dickinson, a spokeswoman for the Council on Responsible Nutrition, a Washington, D.C., trade association representing supplement makers, called the editorial an "unjustified broadside." She said the law was adequate to safeguard the public and that the industry had no more errors or mishaps than food or pharmaceutical producers.

Dr. William Schultz, deputy commissioner for policy at the FDA, said that before 1994, if the agency had concerns about a supplement, it could order the substance off the market until the manufacturer proved it safe. "The biggest impact was that a lot of products probably never got to market," he said.