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The Stuff Legally Allowed in Your Bottle of Supplements is Alarming as Hell

"People don't want prescription medicine, but they'll take an unregulated substance that is misrepresented with bad labeling."

I was a first-year medical student when a classmate showed me his bottle of Clenbutrx. Everything about it had a faux-steroid chic: the name, a portmanteau of 'Clenbuterol' (an asthma-medication-turned-performance-enhancing drug) and 'Rx,' struck boldly above the promise of 'ultra hardcore fat incineration.' They even included a 3cc syringe so users could measure an exact oral dose. I had been a competitive athlete for years—protein powders and supplements were nothing foreign—but this all seemed excessive, especially for an over-the-counter weight loss product.


"It's almost too good," he said. "Seriously, I took too much once and my heart was beating out of my chest." Members of online fitness forums echoed the sentiment after taking it: Some described profusely sweating, being unable to fall asleep, and developing tremors. One person wrote: "within 15 minutes my heart was racing and I thought I was going to die."

The ingredients were a grocery list of chemicals and herbs. One at the very bottom sounded familiar: 3,5'-diiodo-L-thyronine. Save for a single iodide ion, it was structurally identical to triiodothyronine (T3), a hormone made by the thyroid gland. Medical journals confirmed a more alarming similarity—its function. Inside cells, 3,5'-diiodo-L-thyronine, or T2, could exert the same effects as T3, but at a faster rate. It also suppresses thyroid stimulating hormone (TSH), thereby shutting down normal thyroid activity. T2 even stimulates (and I don't mean this in a good way) the cardiovascular system, increasing heart rate and, in high enough doses, the size of the heart.

Heart palpitations. Sweating. Tremors. Insomnia. These were the experiences of some people taking the fat burner—the very same symptoms of hyperthyroidism, or excess thyroid hormone activity. I wasn't just looking at a fat burner; I was looking at a bottle of hormones.

Supplements are ubiquitous: They line the shelves of drug stores, fill the pages of magazines, and bring in $30 billion each year, a profit that more than half of US adults directly support. Their landscape is equally vast, from kids' Flintstones vitamins to the anti-aging serums the aging-conscious use on their wrinkles. It's in this landscape that T2 found its home.


"In the quest for more energy, less weight, and more hair, people tend to look for nonconventional therapies because conventional medicine doesn't address those problems."

The distinction between a "supplement" and a "drug" is not always clear to the consumer. The dietary supplement industry's roots intertwine with the coattails of a scientific giant: Linus Pauling. He was two-time Nobel laureate; as a scientist, he stands alongside Einstein, Salk, and Curie as one of the greatest minds of the 20th century.

However, not all of Pauling's theories were met with accolades. In the late 1960s, he postulated that disease states could be altered by the concentration of different substances within the body. His self-named field of 'orthomolecular medicine' emphasized vitamin C, a substance that Pauling asserted could stave off maladies ranging from the common cold to cancer. He raged against Recommended Dietary Allowances (RDAs)—the suggested amounts of nutrients that a person should consume daily—and his books on the topic were New York Times best-sellers. The movement gathered steam.

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Meanwhile, megavitamin-heads found an advocate in Congress. In 1976, Senator William Proxmire introduced the Vitamin-Mineral Amendment. It sought to eradicate upper limits on RDAs for vitamins and minerals; however, this created a dangerous exemption: The FDA could no longer regulate these supplements as drugs by virtue of their potency. Although the American Medical Association opposed Proxmire, Congress passed the amendment by a resounding majority.


Despite these early victories, the 1980s were a troubling time for the supplement industry. Adverse events associated with dietary supplements were commonplace in the medical literature. Excess vitamin A was linked to increased intracranial pressure (excessive pressure in the skull that negatively affects tissue and brain fluid); ephedrine was linked to strokes in otherwise healthy individuals. In response to mounting concern, Congress drafted amendments to increase FDA oversight of dietary supplements, as well as make it punishable for manufacturers to make unsupported claims.

But Congress had brought a knife to a gunfight. Lobbyists from the industry launched a campaign that likened governmental concern to a witch hunt. The final result was the Dietary Supplement Health and Education Act of 1994. DSHEA loosely defined "dietary supplements" as vitamins, minerals, herbs/botanicals, amino acids, or concentrates/metabolites/extracts of the above. Manufacturers were required to provide the FDA with evidence supporting a product's efficacy, but the FDA bore the burden of proof if safety concerns existed. If a product contained a "new dietary ingredient"—defined as anything not sold in the US prior to October 1994—then the manufacturer only had to provide "reasonable assurance" that the ingredient was safe. If the FDA did not respond within 75 days, the product was free to hit shelves.


One lasting effect of DSHEA was the creation of so-called 'structure-function' claims. On their labels, dietary supplements could not claim to cure or remedy illnesses—these declarations are limited to drugs—however, manufacturers could describe how a supplement theoretically interacts with functions of the body. It was an equivocation: Melatonin no longer treated insomnia, it "supported healthy sleep." Iron tablets no longer managed anemia, they "promoted red cell formation." In trade, manufacturers absolved themselves through a familiar sentence: "These statements have not been evaluated by the Food and Drug Administration."

"Someone says they don't want to take prescription medicine, but they'll easily take an unregulated substance that is misrepresented with bad labeling."

That very phrase was printed on the bottle of Clenbutrx. T2, and all the weight loss products on the market that contained it, fell under the same regulatory guidelines as a multivitamin. "Given the biological significance of thyroid hormones, the presence of thyroid hormones and their metabolites in products marketed as dietary supplements presents a potential safety concern," Lyndsay Meyer, spokeswoman for the FDA, says. "Many products that are marketed as dietary supplements contain active ingredients that have strong biological effects, and their safety is not always assured in all users."

"It's a highly unregulated industry left to the manufacturer and the seller to self-police and make appropriate claims," says Diane Krieger, an endocrinologist and associate professor of medicine at the Florida International University Herbert Wertheim College of Medicine. For fifteen years, Krieger researched dietary supplements with rigorous study designs, employing methods akin to those used for pharmaceuticals. In her experience, public perceptions of safety frequently drove a supplement's popularity. "Oftentimes someone says they don't want to take prescription medicine, but they'll easily take an unregulated substance that is misrepresented with bad labeling." It's no surprise to Krieger that an active thyroid hormone like T2 is readily available on the market: "In the quest for more energy, less weight, and more hair, people tend to look for nonconventional therapies because conventional medicine doesn't address those problems. Most of the time these symptoms are lifestyle-related: lack of exercise, poor diet, bad sleep patterns, too much stress," she says. "Today, people can go to Whole Foods and buy a product for 'thyroid support' that could contain ground up animal thyroids. That sometimes will make them feel a little better, but it's not really addressing the problem." Of the four companies I approached about their use of T2 in weight loss products, only one responded: They had discontinued this fat burner. Shortly after this exchange, any mention of T2 was removed from their website.

Four years have passed since my classmate showed me Clenbutrx. From the looks of it, this product is also off the market. I wear a longer white coat now; I've taken an oath. And today, I'm in clinic, holding a shopping bag full of a patient's medications. The sea of burnt orange prescription bottles is interrupted by one in white. Green Coffee Bean Extract, which reportedly "boosts weight loss naturally."

I review the fine print: "This product is not intended to diagnose, treat, cure, or prevent any disease."

Alexander Daoud is a physician training in New York.

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