Calcium. I’ve heard that radiation causes bone loss.

hmmm seems like I remember hearing something about rosemary? I’m not 100% on that though

edit: yup – here it is: http://www.docstoc.com/docs/24363632/Radiation-and-Rosemary

There was an experimental drug designed to prevent radiation sickness, but last I heard it was discontinued.

There is also a type of chinese mushroom called caterpillar fungus, extracts of which have been proven to protect mice from the effects of whole body irradiation.

I am not aware of any, although @wtfrickinfrack‘s link is interesting (but focusses on communications, which is at the opposite end of the spectrum).

Don’t worry too much about BD scans and chest x-rays though, the radiation dose from those is minimal. Radiographers operating BD machines don’t even use shielding, because the dose is so low. Chest x-rays have a dose equivalent to a few weeks of background radiation, and it is one of the lowest dose examinations available (only higher than a region like a hand or a foot). We use shielding for those because we do dozens of x-rays every day for the length of our career. You only really need to start worrying about the effects of radiation if you have multiple CT scans or Radiotherapy for cancer treatment.

Seaweed has lots of iodine—and it is something I eat—although to be honest, I have no idea if it works.

I like @FireMadeFlesh‘s answer, even though I believe we all get far more radiation that we need—just from flying, going through metal detectors, and the zillions of “harmless” radiation that just must add up even though they are all small in and of themselves.

Radiation creates free radicals in your body. Free radicals can be fought by antioxidants which are found in many fruits and veggies. Just eat more of what the earth put here for us to eat naturally!