Natural Radiation: Why Your
Bananas Are Radioactive And You Shouldn't Care
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
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
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
plant or any other potentially dangerous radiation exposure is
deceptive and gives people a false sense of security.
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
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
So go ahead, eat a banana and savor the flavor of natural radiation.