Can Bananas Make You Radioactive?

You Should Know: Bananas have a radioactive side. They’re loaded with potassium, and about 0.012% of that is potassium-40, a naturally occurring radioactive isotope. Physicists coined an informal unit around bananas the “Banana Equivalent Dose” (BED) to make radiation exposure easier to visualize. One banana is one BED, a dose that’s really so small, it’s essentially nothing. For perspective: a dental X-ray is about 50 BED, and a coast-to-coast flight is around 400. But how worried should we be about this low-level radiation?

Going Deeper: Here’s the thing: you can’t become radioactive by eating certain foods because you already are. You’re carrying around 140 grams of potassium at all times — about 16 milligrams of it radioactive — which makes you roughly 280 times hotter than a banana. Eating one bumps your potassium-40 level up by 0.4%, and your kidneys get rid of that excess within a few hours.

Takeaway: There’s no number of bananas you can eat to become radioactive — your body won’t let it happen. The BED shows that the background radiation we’re all exposed to daily — from the ground, cosmic rays, AirPods, even the buildings we sit in — is nothing to lose sleep over.

Bottom Line: Eat the banana.