A small percentage of potassium – an essential nutrient for health – is radioactive. Radium (another radioactive element) is also naturally found in food containing potassium. Hence, all food especially those high in potassium, such as bananas, potatoes and red meat, are “radioactive”.
Before you go bananas about this, here’s what you should know: The natural radiation from our food is well within the levels that the human body can tolerate.

Read more at https://www.sfa.gov.sg/…/risk-at-…/radiation-and-food-safety.