Thyroid support supplements may be risky

Thyroid disorders are common, which means there’s a market for over-the-counter “thyroid support” dietary supplements. But consumers should be cautious about taking these pills, says the author of a new study.

Thyroid support supplements typically contain two different thyroid hormones -- T3 and T4 -- derived largely from animal thyroid glands, said the author of the study, Dr. Victor Bernet, an endocrinologist at Mayo Clinic, Florida. In a study of 10 brands of supplements, nine contained an animal hormone. Moreover, the amount of hormone in the pills varied widely and often exceeded the doses usually prescribed. One supplement had no T3 or T4.

Thyroid support pills are marketed for their benefits in easing fatigue and for weight control, Bernet said in a news release. However, they most likely don’t help.

“The amount of thyroid hormone a normal person would have to take to lose weight would be dangerously high and there is no evidence that use of thyroid hormone effectively treats fatigue when used in people without actual hypothyroidism,” he said.

Doctors are reporting seeing more abnormal thyroid tests from patients and suspect people are using supplements. Several prescription medications are available to treat thyroid disorders.

The study was funded by the Department of Clinical Investigation at Walter Reed National Military Medical Center and was presented Thursday at the annual meeting of the American Thyroid Assn.

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