Trinidad and Tobago Guardian Online

2022-04-02 09:34:34 By : Ms. yan li liu

Plants are all-nat­ur­al sources of all things good for us, right? It turns out some of our favourite plant-based flavour­ings may do more harm than good.

Sci­en­tists from Johns Hop­kins Kim­mel Can­cer Cen­ter re­port in the jour­nal Food and Chem­i­cal Tox­i­col­o­gy that teas, cof­fees and smoky flavour­ing could be dam­ag­ing our DNA at lev­els com­pa­ra­ble to that caused by chemother­a­py drugs.

The food chem­istry and bi­ol­o­gy re­searchers test­ed the ef­fects of some pop­u­lar foods and food flavour­ings on cell cul­tures in the lab and dis­cov­ered that a well-known re­pair gene called p53 that pro­tects cells from be­com­ing can­cer­ous, was high­ly ac­ti­vat­ed by com­pounds in black and green teas, cof­fee and liq­uid smoke flavour­ing, which is used to add smokey flavour to sausages and meat sub­sti­tutes. The foods caused a 30-fold in­crease in p53 ac­tiv­i­ty when they were added to the cells, which is com­pa­ra­ble to the ef­fect that the chemother­a­py drug etopo­side can have on the can­cer-sup­press­ing gene.

The gene p53 is stim­u­lat­ed when DNA is dam­aged, and the gene trig­gers a se­ries of re­spons­es that at­tempt to re­pair the af­fect­ed DNA. The greater the dam­age to the DNA, the more p53 be­comes ac­ti­vat­ed, and re­searchers have come to view p53 lev­els as a mark­er for DNA in dis­tress.

To mea­sure the p53 ac­tiv­i­ty, the re­searchers tagged the gene in a bunch of hu­man cells to a flu­o­res­cent mark­er that would glow when the gene was ac­ti­vat­ed, and then added di­lut­ed amounts of the foods and flavour­ings. They let the cul­tures sit for 18 hours. Cul­tures with the black and green teas, cof­fee and liq­uid smoke all be­gan to glow, in­di­cat­ing that p53 was hard at work do­ing dam­age con­trol. Tests with oth­er flavour­ings, in­clud­ing fish and oys­ter sauces, smoked pa­pri­ka, wasabi pow­der and kim chee, didn't ac­ti­vate p53 to the same lev­els.

It turns out that these foods and flavour­ings share in com­mon some chem­i­cals–py­ro­gal­lol and gal­lic acid–that the re­searchers be­lieve are re­spon­si­ble for dam­ag­ing the DNA and set­ting off p53. Py­ro­gal­lol is found in smoked foods as well as hair dye, tea, cig­a­rette smoke and cof­fee.

Gal­lic acid is a type of py­ro­gal­lol and is pri­mar­i­ly found in cof­fees and teas. It's not clear how these agents act on DNA, but the harm is con­cern­ing enough to raise the alarm for p53 to swoop in and at­tempt to right the ge­net­ic wrongs.

Pre­vi­ous stud­ies have doc­u­ment­ed sim­i­lar DNA dam­age from liq­uid smoke on the stom­ach lin­ing in rats, but whether it has the same ef­fect on hu­mans isn't known.

On hu­man cells, at least, the ef­fect was strik­ing. "We found that liq­uid smoke, when di­lut­ed a thou­sand fold, was still as strong as the con­cen­tra­tion of etopo­side in a can­cer pa­tient be­ing treat­ed with etopo­side. In fact, it works much the same way.

Etopo­side in can­cer pa­tients dam­ages DNA, that's how you get rid of the can­cers, but it al­so has side ef­fects," says study au­thor Dr Scott Kern, the Kovler Pro­fes­sor of On­col­o­gy and Pathol­o­gy at the Johns Hop­kins Uni­ver­si­ty School of Med­i­cine.

Why would plants har­bour such po­ten­tial­ly dam­ag­ing agents? It's pos­si­ble they help to pro­tect them, pri­mar­i­ly from her­bi­vores look­ing for their next meal. "Plants have been try­ing to keep an­i­mals from eat­ing them for a long time. The plants make poi­sons, and an­i­mals de­vel­op de­fence mech­a­nisms to take on the poi­sons. They have done this to such a great ex­tent that some of these ini­tial poi­sons can be con­sid­ered nu­tri­ents and just food," said Kern.

Which means that their abil­i­ty to cause changes in DNA isn't nec­es­sar­i­ly a cause for alarm. "When you find some­thing dam­ag­ing in food, you can't over­re­act. You have to think, is this one we could be made to han­dle nor­mal­ly, or is this one that should wor­ry us? In this re­port, we don't know the an­swer to that ques­tion," he said.

Some of the aber­ra­tions caused by these plant-based chem­i­cals may be ones that p53 is per­fect­ly ca­pa­ble of fix­ing, for ex­am­ple, al­though more re­search is need­ed to de­ter­mine how ex­ten­sive the dam­age is, and what ef­fect those aber­ra­tions may have on our health. "There's no doubt our body tries to re­pair (the dam­age). It might do a very good job of it. So if we found the sig­na­ture was a re­al­ly weak one, I would wor­ry a lot less," said Kern.

"It means we can re­pair this dam­age re­al­ly eas­i­ly. If the sig­na­ture, how­ev­er, in­volves big dele­tions of DNA or some struc­tur­al DNA le­sions it leaves be­hind, then we could look for these call­ing cards in dis­eases (such as can­cer)."

In the mean­time, the re­searchers are not sug­gest­ing that peo­ple stop drink­ing tea or cof­fee or en­joy­ing smoky-flavoured foods. Still, it doesn't hurt to be cau­tious. Kern, who en­joys cook­ing him­self, has switched to us­ing a smoky scotch to flavour some of his foods. (

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