DENVER (AP) -- A federal judge who lifted the ban on dietary supplements containing low doses of the weight-loss aid ephedra misunderstood the law, the Food and Drug Administration argued Monday in trying to restore the ban.

An attorney for a Utah company that successfully challenged the ban told a three-judge panel of the 10th U.S. Circuit Court of Appeals that if the judge's decision is overturned, the FDA could ban virtually any substance on the market it determines is harmful in large doses, such as vitamin C tablets or peanut butter.

Ephedra, which was linked to dozens of deaths and thousands of reports of health problems such as heart attack or increased blood pressure, was banned two years ago. The agency determined the supplement presents an unreasonable risk of illness or injury at any dose.

Nutraceutical Corp. challenged the ban, and U.S. District Judge Tena Campbell in Salt Lake City ruled last year the ban could not be enforced against supplements containing doses of ephedra up to 10 milligrams.

Christine Kohl, who represented the FDA, told the judges that Campbell did not understand the law or the FDA's duties in regulating dietary supplements. She also said Campbell essentially ignored scientific information on ephedra's effects on the body.

Campbell ruled that the FDA improperly required Nutraceutical to prove there was some benefit to ephedra use. Instead, the judge ruled, the FDA should have had to prove harm.

Kohl said the risk-benefit analysis the agency used was proper because it would have been "irresponsible" to commission a clinical study to prove harm after the FDA began receiving reports of adverse effects.

The FDA based its ban in part on work by a doctor who studied the intake of various substances similar to ephedra rather than on use of ephedra itself. Kohl said because the substance is defined under the law as a dietary supplement rather than a drug, there was little or no scientific data available on its effectiveness or safety because manufacturers aren't required to conduct such studies.

Nutraceutical attorney Jonathan Emord argued that Campbell was correct in determining that the FDA should have studied the effects of various doses of ephedra and issued specific, dose-based regulations rather than a blanket ban.

"Unless you have proof it presents risk at a specific dose level, you can't just willy-nilly ban these things," he said. "This is an irrational scheme."

After the hearing, Emord said if the ban is restored, it would essentially give the FDA license to ban any product it believes can cause harm, even if the harm comes only at extremely high doses.

Emord said Nutraceutical, based in Park City, Utah, has not resumed selling low-dose ephedra supplements because there has been no reliable source available since the ban took effect.

The judges did not indicate when they would rule.

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