Brazil nuts are the world's most radioactive food, containing roughly 1,000
times more radium than most other foods.

The Brazil nut is the most radioactive food, as it naturally contains 0.5
millirem of radium, or a level of radiation is approximately 1,000 times
greater than most foods. To put it into perspective, the average person
receives approximately 300 to 620 millirem of radiation in total each year,
mainly from natural sources. Radium is a radioactive metal that occurs
naturally in the environment, such as in soil. However, high levels can
significantly damage human cells. Brazil nuts have such high levels of
radium because of the deep roots of the trees that grow them. Only minimal
amounts of radiation actually stay in the body after eating Brazil nuts.
Therefore, no negative health effects tend to occur as a result.