Playing It Safe

Worried about radiation? Here’s what you need to know about potassium iodide.

By Lisa James

May 2011


Japan continues to recover from a March 11 earthquake and tsunami that left nearly 28,000 people dead or missing and destruction that may cost more than $300 billion to restore. But events took an ominous turn when the tsunami disabled the Fukushima Daiichi nuclear facility, leading to coolant loss in the plant’s reactors. At this writing, Japanese officials believe that there have been at least
partial meltdowns in several reactor cores and that the cleanup effort will take years.

Higher-than-normal radiation levels have been detected in milk and vegetables from the stricken area. And tiny amounts of radioactive isotopes have been detected at laboratories in Las Vegas—more than 5,500 miles from Fukushima.

Contamination fears have sent thousands of Americans flocking to health food stores for potassium iodide (KI), which can protect the thyroid—a gland that produces energy-regulating hormones—against radiation. But the trick is using KI correctly, and in conjunction with a high-quality multivitamin, to better support long-term health. This approach has been used by NASA for decades to ensure the well-being of astronauts exposed to higher-than-normal radiation levels.

Following NASA’s Lead

Dosage and timing are everything with potassium iodide. If you aren’t within 20 to 30 miles of a nuclear disaster hotspot, it isn’t a good idea to take the massive megadoses appropriate for direct contamination victims. Dosages in the milligram range are considered to be a drug by the Food and Drug Administration. Because health food stores may be prosecuted for selling unlicensed drugs, many have understandably shied away from KI products with 30 mg to 150 mg—or more—in each tablet.

That isn’t to say that lower amounts of KI aren’t effective. Without earth’s atmosphere to protect them, astronauts face cosmic radiation risks during long-duration missions. That’s why NASA has been supplying astronauts with both KI and high-quality multivitamins for years.

Why a multi? “There are ways to greatly modify the radiation response,” says Ann Kennedy, DSc, head of the National Space Biomedical Research Institute’s Radiation Effects Team. “Vitamin deficiencies appear to be extremely important in determining radiation effects.” Kennedy also notes that the American Medical Association has reversed its position on vitamins and now recommends daily multivitamins for everyone.

As for people in Japan who have been exposed to higher-than-normal levels of radiation, Kennedy says, “I think it’s just as important for them to be getting a vitamin tablet every day as it is to be taking potassium iodide.”

Smarter Supplementation

KI occurs naturally in marine plants and animals, including most kinds of seafood. The richest source is the seaweed kelp, which yields 150 micrograms for every three to five grams’ worth of dry weight. This dosage—150 millionths of a gram—is what the body requires every day to maintain optimal thyroid health.

Some people have been taking KI in milligram megadosages. What’s more, in response to supply shortages some unscrupulous manufacturers are using industrial-grade KI instead of a grade suitable for human consumption. Moderate-dosage, pure KI addresses the low risks most people face while supplying the thyroid with the iodide it needs for proper functioning.

For people living near a crippled nuclear plant, high-dose KI may be necessary. But for those thousands of miles away from the danger zone, a moderate dosage—along with a high-grade multivitamin—offers a safer means of thyroid support.

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