Recent events in Japan, with the earthquake, the tsunami, and the subsequent nuclear reactor crisis, have made all of us much more aware of the potential for exposure to excess environmental radiation. And while at this point in time we have not seen a Chernobyl-scale disaster in Japan, the scenario there is still dicey and a day-to-day emergency. At this point in time, we do not know how this will go. We may or may not see a large number of people exposed to greatly elevated levels of radiation, sufficiently high enough to compromise health.

The effects of acute excess radiation exposure can vary greatly, depending on the concentration of radiation, and the duration of exposure. Called ionizing radiation, the radioactive particles that occur during a nuclear event penetrate the body and strip electrons from atoms. In cases of short-term, high-level exposure, radiation raids the body from all angles, breaks down atoms in tissue, and leaves cells so badly damaged that they often can never repair.

Exposure to lethal doses of radiation usually results in death within two months. In less extreme cases of exposure, radiation damage may be sufficient enough to cause cancer and greatly accelerated aging.

And this brings us to kelp. This is a variety of large brown algae in the order Laminariales, also commonly called seaweed. In coastal areas, kelp grows in vast underwater forests, with blade-shaped growths waving in sea currents. Much kelp is eaten as sea vegetables, notably nori (which is wrapped around sushi), kombu, hiziki, and several others. In Japan especially, sea vegetables are commonly eaten on a regular basis.

In addition to hosting a variety of sea creatures, kelp forests also provide rich nutrition for us. In particular, kelp is an excellent source of natural, non-radioactive iodine. And you have choices with kelp. You can buy edible kelp at places like Whole Foods, and make sea vegetables a part of your vegetable intake. Or, you can get kelp tablet supplements, containing approximately 150 micrograms of kelp per tablet, 100 percent of the U.S. recommended daily intake.

With kelp, more is not necessarily better. Too much kelp can lead either to hyperthyroidism or hypothyroidism, both disorders of the thyroid gland that you do not want. So don’t decide to take 10 tablets daily instead of one. If you currently have a thyroid disorder, speak with your health care practitioner before taking kelp tablets. If not, then one kelp tablet a day is an effective way to mitigate the thyroid-related effects of higher environmental radiation.

Iodine will not prevent radiation from interfering with other aspects of health, so it is not an overall protective agent against radiation. It is thyroid-specific.

But a functional thyroid is essential to staying alive, so iodine’s contribution to your health can be great.