Supplements used to boost metabolism may contain thyroid hormones

The New York Times “Well” blog reports that research published in Thyroid indicates that some supplements used to boost metabolism may contain “thyroid hormones that should only be dispensed by prescription.” Investigators “who tested 10 popular thyroid-boosting products sold online found that nine contained the hormones thyroxine (T4) or triiodothyronine (T3), sometimes both.”

While “the amounts varied … in some cases the recommended daily dose contained amounts of thyroid hormone as high or higher than delivered by prescription medications.”

Men’s Journal reports that “lately, researchers have discovered that, for a number of supplements, the contents of the pill don’t match the ingredients on the label. In one recent study, 80 percent of companies tested sold products with fillers, substitutes, and contaminants; another study found a meth-like substance in a common workout supplement. The bottom line: Proceed with caution when taking any herbal supplements. Ask your doctor about the supplement you take and be sure to look for an NSF, USP, or ConsumerLab.com seal on the bottle.”

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