Technically, all food is slightly radioactive. This is because all food and other organic molecules contain carbon, which naturally exists as a mixture of isotopes, including radioactive carbon-14. That's the basis for carbon dating, used to identify the age of fossils. However, some foods emit much more radiation than others. Here's a look at 10 naturally radioactive foods and how much radiation you get from them.
1. Brazil Nuts
If there was an award for "Most Radioactive Food," it would go to Brazil nuts. Brazil nuts contain high levels of two radioactive elements: radium and potassium. Potassium is good for you, used in many biochemical reactions, and one of the reasons why the human body is itself slightly radioactive. Radium occurs in the ground where the trees grow and is absorbed by the plant's root system. Brazil nuts emit over 6,600 pCi/kg of radiation. Most of that radiation passes harmlessly through the body, plus the high levels of healthful selenium and other minerals make these nuts healthy to eat in moderation.
2. Lima Beans
Lima beans are high in radioactive potassium-40 and also radon-226. Expect to get 2 to 5 pCi/kg from radon-226 and 4,640 pCi/kg from potassium-40. You don't any benefit from the radon, but the potassium is a 'good' mineral in lima beans. Lima beans are also a good source of (non-radioactive) iron.
Bananas are sufficiently radioactive that they can set off radiation alarms at ports and airports. They offer 1 pCi/kg from radon-226 and 3,520 pCi/kg from potassium-40. The high potassium content is part of why bananas are so nutritious. You do absorb the radiation, but it's not harmful.
As with carrots, white potatoes offer between 1 and 2.5 pCi/kg of radon-226 and 3,400 pCi/kg of potassium-40. Foods made from potatoes, such as chips and french fries, are similarly slightly radioactive.
6. Low Sodium Salt
Low sodium or lite salt contains potassium chloride, KCl. You'll get around 3,000 pCi/kg. No-sodium salt contains more potassium chloride than low-sodium salt and thus is more radioactive.
7. Red Meat
Red meat contains appreciable amounts of potassium, and thus potassium-40. Your steak or burger glows to the tune of about 3,000 pCi/kg. Meat is also high in protein and iron. The high amount of saturated fat in red meat presents more of a health risk than the radiation.
Beer gets it radioactivity from potassium-40. Expect to get about 390 pCi/kg. That's only about a tenth the radiation you'd get from the same amount of carrot juice, so from a radiation standpoint, which would you say is healthier?
9. Drinking Water
Drinking water isn't pure H2O. Your radiation dose varies according to the water source, On average, expect to pick up about 0.17 pCi/g from radium-226.
10. Peanut Butter
Peanut butter releases 0.12 pCi/g of radiation from radioactive potassium-40, radium-226, and radium-228. It's also high in protein and is a good source of healthy monounsaturated fats, so don't let the slight rad count scare you off.