Cancer biologists find DNA-damaging toxins in common plant-based foods

Mar 27, 2013
coffee

In a laboratory study pairing food chemistry and cancer biology, scientists at the Johns Hopkins Kimmel Cancer Center tested the potentially harmful effect of foods and flavorings on the DNA of cells. They found that liquid smoke flavoring, black and green teas and coffee activated the highest levels of a well-known, cancer-linked gene called p53.

The becomes activated when DNA is damaged. Its gene product makes that mend DNA. The higher the level of DNA damage, the more p53 becomes activated.

"We don't know much about the foods we eat and how they affect cells in our bodies," says Scott Kern, M.D., the Kovler Professor of Oncology and Pathology at the Johns Hopkins University School of Medicine. "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 cautioned that his studies do not suggest people should stop using tea, coffee or , but do suggest the need for further research.

The Johns Hopkins study began a year ago when graduate student Samuel Gilbert, working in Kern's laboratory, noted that a test Kern had developed to detect p53 activity had never been used to identify DNA-damaging substances in food.

For the study, published online February 8 in Food and Chemical Toxicology, Kern and his team sought advice from scientists at the U.S. Department of Agriculture about food products and flavorings. "To do this study well, we had to think like food chemists to extract chemicals from food and dilute food products to levels that occur in a normal diet," he says.

Using Kern's test for p53 activity, which makes a fluorescent compound that "glows" when p53 is activated, the scientists mixed dilutions of the food products and flavorings with and grew them in laboratory dishes for 18 hours.

Measuring and comparing p53 activity with baseline levels, the scientists found that 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.

Previous studies have shown that liquid smoke flavoring damages DNA in animal models, so Kern's team analyzed p53 activity triggered by the chemicals found in liquid smoke. Postdoctoral fellow Zulfiquer Hossain tracked down the chemicals responsible for the p53 activity. The strongest p53 activity was found in two chemicals: pyrogallol and gallic acid. Pyrogallol, commonly found in smoked foods, is also found in cigarette smoke, hair dye, tea, coffee, bread crust, roasted malt and cocoa powder, according to Kern. Gallic acid, a variant of pyrogallol, is found in teas and coffees.

Kern says that more studies are needed to examine the type of caused by pyrogallol and gallic acid, but there could be ways to remove the two chemicals from foods and flavorings.

"We found that Scotch whiskey, which has a smoky flavor and could be a substitute for liquid smoke, had minimal effect on p53 activity in our tests," says Kern.

, produced from the distilled condensation of natural smoke, is often used to add smoky flavor to sausages, other meats and vegan meat substitutes. It gained popularity when sausage manufacturers switched from natural casings to smoke-blocking artificial casings.

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.

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JRi
3.9 / 5 (7) Mar 27, 2013
But tea is known to be healthy! Maybe you want the food to trigger p53 activity. Maybe this kills emerging cancer cells and saves the healthy ones.
mb9
5 / 5 (6) Mar 27, 2013
"The higher the level of DNA damage, the more p53 becomes activated." This does not necessarily infer causality. Lots of researchers these days do not understand the difference between an association and a causal agency. It seems like every now en then articles appear and claim this or that substance found naturally in some foods to 'cause' cancer.
Caliban
3.3 / 5 (7) Mar 27, 2013
Undoubtably, some substances in natural foods do have the potential to cause cancer.

Plants evolved to produce certain toxins to discourage other organisms from consuming them as a matter of simple self-defense. However, many of these compounds have beneficial effects up to a certain threshold concentration, as opposed to directly harmful substances like cyanide in the pits of certain fruits, for example.

I question the usefulness of this research, as it only suffices to reiterate already known facts, even if it does manage to pinpoint an important link in the causal chain.

And, given that humans have been eating natural foods for their entire existence, and, indeed --their entire evolutionary existence since the primordial beginnings of terrestrial Life-- again, this research seems pretty meaningless.

Of far more pressing concern are the effects of synthetic, processed, INTRODUCED substances in the food we eat.

Given the industry-led push to legitimize

CONTD
Caliban
3.3 / 5 (7) Mar 27, 2013
CONTD

the use of additive-laden, chemically-processed, and GMO foods, and to provide them with some aura of being perfectly safe and healthy --indeed, even moreso than organically produced foods--
it comes as no surprise that research comes to light that seeks to question the relative benefits of "natural" versus industrially produced foods.

Tellingly, we don't see any indication that this research has been accepted for publication in a peer-reviewed journal, either, although that may just be an oversight. I suspect that an inquiry into the funding sources of the research(or the researchers' affiliations) might reveal information of considerable interest to persons that might detect an odor arising from these findings.
robeph
5 / 5 (2) Mar 27, 2013
Carcinogenic toxins wouldn't actually serve as an evolved defense mechanism, since the long period of time it'd take to induce cancers do little to either defend the plant from consumption or to trigger an avoidance in the consuming animals. The DNA damaging effect would have little use in this context.

I understand the researcher's suggestion that defensive chemistry and such ought be examined, but the inference his quote makes within the context of this article by the writer is implying more about the discovery of possible dna damage caused by various chemicals. The implication that it is related in any sense to a defense mechanism in any manner beyond coincidence is very unlikely.
Lurker2358
4 / 5 (4) Mar 27, 2013
But tea is known to be healthy! Maybe you want the food to trigger p53 activity. Maybe this kills emerging cancer cells and saves the healthy ones.


I was thinking the same thing. Either the author is not presenting the information correctly, or he is making a causal connection which is not necessarily true.

What was not said is whether the test ingredients promotes p53 production directly, or whether they are in fact causing harmful mutations, which the cell then makes p53 in response to try to fix it.

If it's the first thing, then those ingredients are actually very good. If it's the second then it sucks.

It seems he concludes p53 production is a sign that the ingredient caused cancer and the cell reacted, but there is the option that the ingredient caused increased p53 directly for some reason.
Lurker2358
3 / 5 (2) Mar 27, 2013
If coffee and tea are carcinogenic, then why doesn't everybody get mouth, throat, and digestive cancers? or some sort of metastasized cancer involving cells originally from those organs?

Besides, who's cells was he using? Sample size 1 for human test subjects doesn't convince me in the case of cancers.

Like why do some people smoke 2 packs of cigarettes for 40 years and never get lung cancer, and another guy who never smoked a cigarette in his life dies from lung cancer...it makes not sense either. Yeah I know the statistics say cigarettes cause cancer, just saying though.
DGBEACH
1 / 5 (1) Mar 28, 2013
" I suspect that an inquiry into the funding sources of the research(or the researchers' affiliations) might reveal information of considerable interest to persons that might detect an odor arising from these findings."

Read more at: http://phys.org/n...html#jCp]http://phys.org/n...html#jCp[/url]

"We found that Scotch whiskey, which has a smoky flavor and could be a substitute for liquid smoke, had minimal effect on p53 activity in our tests,"

Read more at: http://phys.org/n...html#jCp]http://phys.org/n...html#jCp[/url]

...this article brought to you by the Scotch Whiskey producers of the world :)
Pedro Alvarez
5 / 5 (4) Mar 28, 2013
What a confusing article and/or study.

"The strongest p53 activity was found in two chemicals: pyrogallol and gallic acid. Gallic acid, a variant of pyrogallol, is found in teas and coffees."

Wikipedia: "Gallic acid acts as an antioxidant and helps to protect human cells against oxidative damage."

"Cancer biologists find DNA-damaging toxins in common plant-based foods" =! "The p53 gene becomes activated when DNA is damaged. Its gene product makes repair proteins that mend DNA. The higher the level of DNA damage, the more p53 becomes activated."

They've found an increased p53 activity, not a higher DNA damage, right?

Too many questions remain open. Therefore please stay away from assumptions and suggestions. That's confusing and probably bad science.
slack
not rated yet Mar 31, 2013
Pedro summarises the issues correctly.
As usual, this report is confusing and MAY indicate that what is occurring is actually the opposite to what is reported in the article heading.
Again, bad editing in PhysOrg. This is quite disappointing...
tekram
5 / 5 (1) Mar 31, 2013
http://www.hopkin...ed_foods
The irony is that Scott Kern throws in the statement: "We found that Scotch whiskey, which has a smoky flavor and could be a substitute for liquid smoke, had minimal effect on p53 activity in our tests," says Kern. But SCOTT E. KERN, MD is also the inaugural Everett and Marjorie Kovler Professor of Pancreas Cancer Research. EVERETT KOVLER was a Chicago area businessman, and president of the Jim Beam Bourbon Company.

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