Radiological health expert Daniel Hayes of the New York City department of health and mental hygiene said calcitriol, the active form of vitamin D, may protect people from background radiation and could be used as a safe protective agent before or after a low-level nuclear incident.

In terms of protecting people from the long-term effects of radiation, cancer formation would be the main focus. The ideal agent would act by blocking DNA damage or by halting the progression of damaged cells that might eventually grow into cancers, Hayes said.

While a drug is yet to be found with such ideal radio-protective properties, Hayes said vitamin D, and in particular its biologically active form, could be the key ingredient in radiological protection.

"Our general understanding and appreciation of the multifaceted protective actions of vitamin D have recently entered a new era," Hayes wrote in the International Journal of Low Radiation. "It is now becoming recognized that its most active molecular form -- 1,25-dihydroxyvitamin D3 -- may offer protection against a variety of radiation- and otherwise-induced damages."