The war in Ukraine heightened fears about nuclear leaks or attacks. It also piqued interest in—and stockpiling of—iodide (a salt compound containing the element iodine) pills. What’s the connection? Iodine may help preserve human health in case of nuclear exposure.

Concerns grew over recurring power cuts to the Zaporizhzhia nuclear plant in southeastern Ukraine. Experts say such outages increase the risk of nuclear meltdown. (See Ukraine War Continues.)

During a nuclear strike or plant failure, radioactive substances such as radioactive iodine escape into the environment. Those substances can lead to serious or even fatal poisoning for people and animals. Radiation increases the risk of cancer if it enters the body—usually by absorption through the skin, eating contaminated food, or inhalation.

Exposure is especially dangerous for children. Health risks can last for many years, according to the World Health Organization.

So if iodine causes health problems, why would anyone take iodine tablets? The tablets contain potassium iodide (KI)—a stable, not radioactive, compound.

The human thyroid gland soaks up iodine and uses it to produce important hormones. Potassium iodide pills work by filling up the thyroid with a stable version of iodine so that the radioactive kind can’t get in. If the thyroid is already packed with beneficial KI, it won’t be able to absorb harmful iodine after a nuclear accident.

Russian President Vladimir Putin’s actions in Ukraine show little regard for human life. He has threatened to use “all means necessary” to win the war. His statements raise the threat of nuclear warfare and radioactive contamination.

Some European countries began stockpiling iodide tablets. Officials in Ukraine distribute pills. Polish authorities are making potassium iodide available. Pharmacies in Finland ran low on the pills after that country’s health ministry suggested each household buy a single emergency dose.

KI offers protection against one kind of nuclear exposure. But it doesn’t protect against other kinds of radioactive threats. A nuclear bomb, for example, can release different kinds of radiation and radioactive material. These can cause much harm.

But KI also has side effects. Those include the potential for rash, inflammation, or stomach upset. According to the U.S. Food and Drug Administration, folks over age 40 probably shouldn’t take iodide tablets—unless their expected exposure is very high.

Health authorities caution that KI should be taken only in certain nuclear emergencies. It also works best if it’s taken close to the time of exposure, not in advance.

According to nuclear policy researcher Edward Geist, taking KI pills may help. But it isn’t “a silver bullet.”

Why? God created the human body with some amazing defenses. Learning how the thyroid operates makes us marvel at His design and care, and helps us prepare mercifully for potential harm.