Plants are all-natÂurÂal sources of all things good for us, right? It turns out some of our favourite plant-based flavourÂings may do more harm than good.
SciÂenÂtists from Johns HopÂkins KimÂmel CanÂcer CenÂter reÂport in the jourÂnal Food and ChemÂiÂcal ToxÂiÂcolÂoÂgy that teas, cofÂfees and smoky flavourÂing could be damÂagÂing our DNA at levÂels comÂpaÂraÂble to that caused by chemotherÂaÂpy drugs.
The food chemÂistry and biÂolÂoÂgy reÂsearchers testÂed the efÂfects of some popÂuÂlar foods and food flavourÂings on cell culÂtures in the lab and disÂcovÂered that a well-known reÂpair gene called p53 that proÂtects cells from beÂcomÂing canÂcerÂous, was highÂly acÂtiÂvatÂed by comÂpounds in black and green teas, cofÂfee and liqÂuid smoke flavourÂing, which is used to add smokey flavour to sausages and meat subÂstiÂtutes. The foods caused a 30-fold inÂcrease in p53 acÂtivÂiÂty when they were added to the cells, which is comÂpaÂraÂble to the efÂfect that the chemotherÂaÂpy drug etopoÂside can have on the canÂcer-supÂpressÂing gene.
The gene p53 is stimÂuÂlatÂed when DNA is damÂaged, and the gene trigÂgers a seÂries of reÂsponsÂes that atÂtempt to reÂpair the afÂfectÂed DNA. The greater the damÂage to the DNA, the more p53 beÂcomes acÂtiÂvatÂed, and reÂsearchers have come to view p53 levÂels as a markÂer for DNA in disÂtress.
To meaÂsure the p53 acÂtivÂiÂty, the reÂsearchers tagged the gene in a bunch of huÂman cells to a fluÂoÂresÂcent markÂer that would glow when the gene was acÂtiÂvatÂed, and then added diÂlutÂed amounts of the foods and flavourÂings. They let the culÂtures sit for 18 hours. CulÂtures with the black and green teas, cofÂfee and liqÂuid smoke all beÂgan to glow, inÂdiÂcatÂing that p53 was hard at work doÂing damÂage conÂtrol. Tests with othÂer flavourÂings, inÂcludÂing fish and oysÂter sauces, smoked paÂpriÂka, wasabi powÂder and kim chee, didn't acÂtiÂvate p53 to the same levÂels.
It turns out that these foods and flavourÂings share in comÂmon some chemÂiÂcals–pyÂroÂgalÂlol and galÂlic acid–that the reÂsearchers beÂlieve are reÂsponÂsiÂble for damÂagÂing the DNA and setÂting off p53. PyÂroÂgalÂlol is found in smoked foods as well as hair dye, tea, cigÂaÂrette smoke and cofÂfee.
GalÂlic acid is a type of pyÂroÂgalÂlol and is priÂmarÂiÂly found in cofÂfees and teas. It's not clear how these agents act on DNA, but the harm is conÂcernÂing enough to raise the alarm for p53 to swoop in and atÂtempt to right the geÂnetÂic wrongs.
PreÂviÂous studÂies have docÂuÂmentÂed simÂiÂlar DNA damÂage from liqÂuid smoke on the stomÂach linÂing in rats, but whether it has the same efÂfect on huÂmans isn't known.
On huÂman cells, at least, the efÂfect was strikÂing. "We found that liqÂuid smoke, when diÂlutÂed a thouÂsand fold, was still as strong as the conÂcenÂtraÂtion of etopoÂside in a canÂcer paÂtient beÂing treatÂed with etopoÂside. In fact, it works much the same way.
EtopoÂside in canÂcer paÂtients damÂages DNA, that's how you get rid of the canÂcers, but it alÂso has side efÂfects," says study auÂthor Dr Scott Kern, the Kovler ProÂfesÂsor of OnÂcolÂoÂgy and PatholÂoÂgy at the Johns HopÂkins UniÂverÂsiÂty School of MedÂiÂcine.
Why would plants harÂbour such poÂtenÂtialÂly damÂagÂing agents? It's posÂsiÂble they help to proÂtect them, priÂmarÂiÂly from herÂbiÂvores lookÂing for their next meal. "Plants have been tryÂing to keep anÂiÂmals from eatÂing them for a long time. The plants make poiÂsons, and anÂiÂmals deÂvelÂop deÂfence mechÂaÂnisms to take on the poiÂsons. They have done this to such a great exÂtent that some of these iniÂtial poiÂsons can be conÂsidÂered nuÂtriÂents and just food," said Kern.
Which means that their abilÂiÂty to cause changes in DNA isn't necÂesÂsarÂiÂly a cause for alarm. "When you find someÂthing damÂagÂing in food, you can't overÂreÂact. You have to think, is this one we could be made to hanÂdle norÂmalÂly, or is this one that should worÂry us? In this reÂport, we don't know the anÂswer to that quesÂtion," he said.
Some of the aberÂraÂtions caused by these plant-based chemÂiÂcals may be ones that p53 is perÂfectÂly caÂpaÂble of fixÂing, for exÂamÂple, alÂthough more reÂsearch is needÂed to deÂterÂmine how exÂtenÂsive the damÂage is, and what efÂfect those aberÂraÂtions may have on our health. "There's no doubt our body tries to reÂpair (the damÂage). It might do a very good job of it. So if we found the sigÂnaÂture was a reÂalÂly weak one, I would worÂry a lot less," said Kern.
"It means we can reÂpair this damÂage reÂalÂly easÂiÂly. If the sigÂnaÂture, howÂevÂer, inÂvolves big deleÂtions of DNA or some strucÂturÂal DNA leÂsions it leaves beÂhind, then we could look for these callÂing cards in disÂeases (such as canÂcer)."
In the meanÂtime, the reÂsearchers are not sugÂgestÂing that peoÂple stop drinkÂing tea or cofÂfee or enÂjoyÂing smoky-flavoured foods. Still, it doesn't hurt to be cauÂtious. Kern, who enÂjoys cookÂing himÂself, has switched to usÂing a smoky scotch to flavour some of his foods. (Time.com)
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