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Study: 'Thyroid Support' Supplements May Be Risky

Researchers Say Supplements Contain 'Significant' Amounts of Thyroid Hormone

Thyroid Support Supplements Legal

The supplements are legal as long as they aren't spiked with pharmaceutical drugs, according to federal law. That law, passed in 1994, permits the sale of "a dietary substance for use by man to supplement the diet by increasing the total dietary intake (e.g., enzymes or tissues from organs or gland)."

Firms that sell the supplements are responsible for "determining" that their products are safe and that claims made about them "are substantiated by adequate evidence to show they are not false or misleading." But the law exempts these supplements from having to be approved by the FDA.

"Thyroid support supplements have been around for a long time," Duffy MacKay, ND, vice president for scientific and regulatory affairs for the Council for Responsible Nutrition (CRN), tells WebMD. CRN is the trade group that represents the supplement industry.

"The presence of desiccated glands in dietary supplements is perfectly legal," MacKay says. "The amounts of hormone in the product should reflect what naturally occurs in the [animal] gland itself. ... These are not extremely high levels of thyroid hormone."

But MacKay says his comments are limited to firms "following the rules." He condemns "spiked products masquerading as supplements."

The FDA did not respond to WebMD's request for comment on the Bernet study findings.

Bernet says thyroid support products should be more tightly regulated. MacKay says Bernet is entitled to his opinion, but that if he wants things changed he should write to his congressman to seek a change in federal law.

However, MacKay and Bernet fully agree on at least one major point: Anyone thinking of taking a thyroid support supplement should talk with a medical professional, and should be sure to tell all of their doctors what they are taking.

Bernet reported the study findings in a presentation to the annual meeting of the American Thyroid Association, held Oct. 26-30 in Indian Wells, Calif.

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