Common Spices Protect Bacteria During Irradiation

Researchers in India say that some common spices — red chili powder, black pepper and turmeric — can actually prevent bacteria such as E. coli from being destroyed by irradiation. On the plus side, however, the researchers believe their findings indicate that spice extracts could be used to protect healthy tissue in people undergoing radiation therapy.

The research, conducted at the Bhabha Atomic Research Centre in Mumbai, India, is reported in the current print issue (April 17) of the Journal of Agricultural and Food Chemistry, a peer-reviewed monthly publication of the American Chemical Society, the world’s largest scientific society.

The finding that the spices protect some bacteria against irradiation was “contrary to expectations,” according to the article. “The observed protection of microbes may essentially be due to the protection of their DNA by the constituents of spices,” say the researchers. Chili offered the highest level of protection, followed by black pepper and turmeric.

Besides the unexpected finding of the spices’ ability to shield bacteria from irradiation, the test-tube study also “draws attention to the radioprotective effect of spices,” says lead researcher Arun Sharma, Ph.D.

“Spices potentially can offer protection to organisms against the damaging effects of gamma radiation, and also offer hope for the development of better radioprotective agents,” claims Sharma.

Two antioxidants in black pepper and turmeric — piperine and curcumin — were found to help protect the bacteria’s DNA from damage by irradiation during the study. “However,” the article notes, “these compounds may not be the sole protecting agents present in spices.”

The findings from the study are not a cause for concern, says Shamra. The irradiation doses routinely used to process prepared foods are high enough to kill any E. coli, he points out.

Several other food constituents — including some proteins, fats and carbohydrates — also are known to protect microorganisms from decontamination by irradiation, as well as by heat and chemicals, says Sharma.

The researchers evaluated the spices against two microorganisms during the study: Escherichia coli and Bacillus megaterium.