Dr. Scott Kern of the Johns Hopkins University School of Medicine in Baltimore said the p53 gene becomes activated when DNA is damaged. It makes repair proteins that mend DNA. The higher the level of DNA damage, the more p53 becomes activated, Kern said.
"We don't know much about the foods we eat and how they affect cells in our bodies," Kern said in a statement. "But it's clear that plants contain many compounds that are meant to deter humans and animals from eating them, like cellulose in stems and bitter-tasting tannins in leaves and beans we use to make teas and coffees, and their impact needs to be assessed."
Kern said he is not suggesting people stop using tea, coffee or flavorings, but he did suggest the need for further research.
Kern and graduate student Samuel Gilbert, used Kern's test for p53 activity, which makes a fluorescent compound that "glows" when p53 is activated. They mixed dilutions of the food products and flavorings with human cells and grew them in laboratory dishes for 18 hours.
Measuring and comparing p53 activity with baseline levels, the scientists found liquid smoke flavoring, black and green teas and coffee showed up to nearly 30-fold increases in p53 activity, which was on par with their tests of p53 activity caused by a chemotherapy drug called etoposide.
Other flavorings like fish and oyster sauces, Tabasco and soy sauces and black bean sauces showed minimal p53 effects in Kern's tests, as did soybean paste, kim chee, wasabi powder, hickory smoke powders and smoked paprika, the study said.
Many studies have linked coffee and green tea with reducing the risk of some cancers and other diseases.
The findings were published in the journal Food and Chemical Toxicology.