WHEN AN EARTHQUAKE HIT JAPAN BACK IN March, tremors triggered seismographs more than 6,000 miles away in Texas. But what the quake really rattled on this side of the globe were the nerves of Americans: Once the news came out that the Fukushima Daiichi nuclear reactors had been damaged, people in the States began worrying that a killer plume of radiation might waft across the Pacific.

Within days, poison-control centers and state health departments as far east as Pennsylvania were fielding calls from people wondering about protection from an oncoming cancer cloud—specifically, questions about potassium iodide, a form of stable iodine that can guard a person’s thyroid gland against harmful radioactive iodine. The same pills that the U.S. government had issued to its employees in Japan were soon being hoarded by a public suddenly obsessed with iodine.

Of course, a nuclear storm never did sweep across the country. Somewhere between Fukushima and Fresno the danger dissipated, and gradually, so did our obsession with iodine.

But beyond this happy ending, another danger lurks. The risk of radiation may have vanished, but a national health threat remains. And we still need iodine to save the day.

LOCATED IN THE FRONT OF YOUR NECK, JUST below your Adam’s apple, the thyroid gland is often described as the thermostat of the human endocrine system. It regulates your body’s use of energy, and creates and stores hormones that control everything from your metabolism to your growth rate. The essential chemical for all these functions is iodine. Without enough of this element pumping through your thyroid, you may begin to experience fatigue, depression, lethargy, cloudy thinking, and weight gain. Left untreated, an iodine deficiency may potentially cause thyroid cancer and, some doctors theorize, even heart disease.

Fatigue? Lethargy? Cloudy thinking? Right: This pretty much describes the symptoms of every man in America on any given workday. But what if what you’ve come to consider just a case of the Mondays is actually an out-of-whack thermostat? And what if the belly fat that so many men can’t seem to shed exists at least in part because of a metabolic malfunction?

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