Are Bananas Radioactive?

Written by

Melissa Petruzzello

Fact-checked by

Britannica Editors

History

While it might seem like an oxymoron, bananas are a healthy—and radioactive—snack. As it turns out, those two facts are closely connected, as it is the fruit’s abundance of potassium that makes it radioactive. Potassium is an essential nutrient that helps nerves, muscles, and the heart function properly. Most potassium atoms are a stable form known as potassium-39, containing 19 protons and 20 neutrons. A tiny fraction—about 0.01 percent—is made up of atoms of a...