Researchers have newly discovered a surprising and potentially significant reason why eating foods continuously cooked at high temperatures, comparable to beef and deep-fried fare, elevates cancer risk. The alleged offender: DNA inside the food that is been damaged by the cooking process.

As shown for the primary time known to the authors, this study by Stanford scientists and their collaborators on the National Institute of Standards and Technology (NIST), the University of Maryland, and Colorado State University reveals that components of heat-marred DNA might be absorbed during digestion and incorporated into the DNA of the patron. That uptake directly places damage in the patron’s DNA, potentially triggering genetic mutations that will eventually result in cancer and other diseases.

While it’s too soon to say this happens in humans – the study only observed heat-damaged DNA component uptake and increased DNA injury in lab-grown cells and mice – the findings could have essential implications for dietary selections and public health.

Now we have shown that cooking can damage DNA in food, and have discovered that consumption of this DNA could also be a source of genetic risk. Constructing upon these findings could really change our perceptions of food preparation and food selections.”

Eric Kool, study senior creator, the George A. and Hilda M. Daubert Professor in Chemistry within the Stanford School of Humanities and Sciences

Yong Woong Jun, a former postdoctoral research affiliate in chemistry at Stanford and now on the Korea Advanced Institute of Science and Technology, is the lead creator of the study, which published June 1 in ACS Central Science.

Novel genetic hazard

Many studies link the consumption of charred and fried foods to DNA damage, and attribute the harm to certain small molecules that form so-called reactive species within the body. Of note, nevertheless, those small molecules produced in typical cooking number many 1000’s of times lower than the quantity of DNA occurring naturally in foods, Kool says.

For those reactive species to cause DNA damage, they have to physically encounter DNA in a cell to trigger a deleterious chemical response – a rare event, in all likelihood. In contrast, key components of DNA referred to as nucleotides which might be made available through normal breakdown of biomolecules – as an example, during digestion – are readily incorporated into the DNA of cells, suggesting a plausible and potentially significant pathway for damaged food DNA to inflict damage on other DNA downstream in consumers.

“We do not doubt that the small molecules identified in prior studies are indeed dangerous,” says Kool. “But what has never been documented before our study is the doubtless large quantities of heat-damaged DNA available for uptake right into a consumer’s own DNA.”

We’re what we eat

Many individuals aren’t aware that foods we eat – meat, fish, grains, veggies, fruit, mushrooms, you name it – include the originating organisms’ DNA. The oversight is comprehensible, since DNA doesn’t appear on nutrition labels in the identical manner as protein, carbohydrates, fat, vitamins, and minerals. Yet the amounts of devoured DNA should not negligible. For instance, a roughly 500 gram (16 ounce) beef steak incorporates over a gram (0.04 ounce) of cow DNA, suggesting that human exposure to potentially heat-damaged DNA is likewise not negligible.

Investigating the nitty-gritty of how complex DNA molecules are repaired – each after unavoidable natural errors, in addition to damage induced by environmental exposures – is a chief aim of Kool’s lab at Stanford. To this end, Kool’s lab and their collaborators have devised technique of inducing and measuring specific forms of harm to DNA.

While pursuing this line of research, Kool began wondering a few hypothetical connection to foodborne DNA and the well-known technique of the body “salvaging” and reusing DNA scraps. The researchers proceeded to cook foods – namely, ground beef, ground pork, and potatoes – through either 15-minute boils at 100 degrees Celsius (212 degrees Fahrenheit) or 20-minute mild roastings at 220 C (about 430 F). The Stanford researchers then extracted DNA from these foods and sent the samples to collaborators at NIST.

The NIST team, led by Miral Dizdaroglu, showed that each one three foods exhibited DNA damage when boiled and roasted, and better temperatures increased DNA damage in nearly all instances. Interestingly, even just boiling, a comparatively low cooking temperature, still resulted in some DNA damage. Other intriguing results emerged as well – potatoes, as an example, incurred less DNA damage at higher temperatures than meat for unknown reasons.

The 2 commonest kinds of harm involved a nucleotide component containing a compound called cytosine changing chemically to a related compound called uracil and the addition of oxygen to a different compound called guanine. Each sorts of DNA damage are genotoxic, in that they will ultimately impair gene functioning and foster mutations that cause cells to duplicate uncontrollably as cancer.

Next, Kool’s team exposed lab-grown cells and fed mice an answer containing the heat-damaged DNA components in high concentrations. The researchers used an progressive tool, created in-house in Kool’s lab in previous work, that tags sites of damaged DNA with fluorescent molecules, making the extent of the damage easy to measure. Overall, the lab-grown cells showed significant DNA damage resulting from taking over heat-damaged DNA components. As for the mice, DNA damage appeared prominently within the cells lining the small intestine, which is smart because that is where much of food digestion takes place.

Meriting further investigation

The team now plans to delve deeper into these eyebrow-raising, preliminary findings. One future avenue of research is testing a broader number of foods, following up on the concept that foods with high levels of DNA content, comparable to animal products, could pose more of a possible genetic menace than low-DNA-level sustenance comparable to potatoes and other plants. The researchers also plan on examining cooking methods that simulate different food preparations – as an example, cooking food for longer than simply 20 minutes.

Importantly, the scope of research might want to expand to the long-term, lower doses to heat-damaged DNA expected over a long time of consumption in typical human diets, versus the high doses administered within the proof-of-concept study.

“Our study raises a whole lot of questions on a completely unexplored, yet possibly substantial chronic health risk from eating foods which might be grilled, fried, or otherwise prepared with high heat,” said Kool. “We do not yet know where these initial findings will lead, and we invite the broader research community to construct upon them.”

Source:

Journal reference:

Jun, Y. W., et al. (2023) Possible Genetic Risks from Heat-Damaged DNA in Food. ACS Central Science. doi.org/10.1021/acscentsci.2c01247.