Natural Radiation: Why Your Bananas Are Radioactive And You Shouldn't Care

Natural radiation is everywhere, including your food. If you live in a stone house, you're getting a higher dose of radiation than you would living in a wooden house. If you're sitting outside, you're being bathed by radioactive cosmic rays. If there's a newspaper on your lap, it's emitting radiation too.

Even your body emits radiation into the environment around you, and nothing you can do can stop the constant bombardment short of wearing a lead-lined suit.

Recently, the amount of natural radiation in food has caught the public eye. Doctor Oz recently compared the amount of radiation from a chest x-ray to a large dose of bananas on his popular TV show, causing some people to become worried.

So why are your bananas radioactive, and does it matter at all?

Natural Radiation: What Makes Your Banana Radioactive?

Nearly all foods produce natural radiation, although some to a greater degree than others.

Every year a person consumes a total average dose of 40 millirems of radiation from all of their food intake (1) out of an average total of 360 millirems of radiation from all sources.

Potatoes, many types of seeds, kidney beans, and a variety of nuts are among the foods emitting the most radiation. Brazil nuts are near the top of the list with 12,000 picocuries per kg (2).

Bananas, by comparison, have an average radiation level of only 3520 picocuries per kg (3), although this is still high enough to place them among the more radiation-heavy foods. The source of the radiation is potassium, specifically radioactive isotope K40 inside potassium. Anything with potassium is radioactive because of this isotope, but few foods have the banana's potassium punch.

To put this in perspective with the average dose of 360 millirems of radiation per year, if you ate a banana a day you'd take in 3.6 millirems during that year.

By comparison a chest x-ray is about 10 millirems and a six-hour airplane trip will bombard you with 2 millirems.

There's absolutely no reason to believe that any amount of bananas, or any other food for that matter, is of any threat due to radiation.

Natural Radiation: The Banana Equivalent Dose

So why is Dr. Oz picking on the banana, which has a long track record of being healthy?

There's actually some precedent. Those in the nuclear power industry use what they call the Banana Equivalent Dose as a way of putting radiation into perspective for the lay person who doesn't know what picocuries or millirems are.

So, for instance, someone wanting to build a new nuclear power plant would explain the risk to residents by saying that living within 50 miles of the new plant will expose them to only 0.09 millirem, or 1.64 "banana units" a year.

Natural Radiation: Why Bananas Are A Bad Example

Using the banana to compare with the radiation emitted by a nuclear power plant or any other potentially dangerous radiation exposure is downright deceptive and gives people a false sense of security.

Natural Radiation Symbol

The comparison implies that all radioactive isotopes are created equal, and that there is no difference between our 3520 picocuries for a kg of bananas and the same amount of radioiodine, a major hazard involved in the production of nuclear power.

The first major problems with the comparison is that different types of isotopes have different characteristics in terms of half life, and whether it is alpha, beta, or gamma radiation.

The second is that the potassium in bananas does not stay in the body, but other types of radiation can, accumulating in organs and being absorbed by the blood stream.

Although it doesn't have a nice ring to it, if someone decided to create the Brazil Nut Equivalent Dose, it would actually make more sense than using bananas. Brazil nuts get their radiation from Barium, which the body can accumulate.

Potassium, however, is something the body easily excretes, always striving to maintain homeostasis (4). Sure, when you eat a banana the amount of potassium in you does go up, but only for a short amount of time before it is excreted.

Now you could argue that I'm being overly picky here. You still get radiation exposure just by sitting next to a banana, after all, and the Banana Equivalent Dose is about the natural radiation in our food and environment generally, not bananas specifically.

Maybe it's the banana-loving raw foodist in me, but I still think it doesn't work.

Natural Radiation: Following Up

Radiation is everywhere, especially in what you put in your mouth. There's no reason to believe any of it is harming you, and you don't have much of a choice. Either you eat radioactive food or you die of starvation.

So go ahead, eat a banana and savor the flavor of natural radiation.

Find other interesting nutrition articles like this one on natural radiation.

Learn how bananas fit into a healthy raw food diet.

Natural Radiation Sources:

(1) Radiation. Risks and Realities, US Environmental Protection Agency http://www.epa.gov/rpdweb00/docs/402-k-07-006.pdf
(2) Penn-Franca, et al. Radioactivity of Brazil Nuts. Health Physics 14: 95-99; 1968.
(3) CRC Handbook on Radiation Measurement and Protection, Vol 1 p. 620 Table A.3.7.12, CRC Press, 1978.
(4) Brenner, B.M. (Editor); Stein, J.H. (Editor) (1979). Acid–Base and Potassium Homeostasis. Churchill Livingstone. ISBN 0443080178.

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