High heat from cooking may lead to DNA damage, cancer

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Cooking food at high temperatures has been linked to increased health risks. Dave Keeley/500px/Getty Images
  • Several studies have found cooking foods at high temperatures is associated with health risks.
  • Now, a new study suggests cooking at high temperatures may damage the DNA of food.
  • Researchers believe pieces of this damaged DNA may be absorbed during digestion, and the damage is then absorbed into the consumer’s DNA.
  • The study suggests the consumption of damaged food DNA may pose a genetic risk to the consumer.

In the past, some researchers hypothesized that health risks are linked to high-temperature cooking because the cooking process produces certain small molecules that react with the DNA in consumers’ bodies.

In his lab, dr. Eric Kool, the George A. and Hilda M. Daubert Professor in Chemistry at the Stanford School of Humanities and Sciences, frequently studies cellular mechanisms of DNA repair.

Dr. Kool and other Stanford scientists then collaborated with researchers from the National Institute of Standards and Technology (NIST) at the University of Maryland, and Colorado State University to produce a study looking at whether the DNA in food, damaged by heat, could serve as a potential source of genetic damage in mice.

“We decided to see what happens to human cells when they are exposed to damaged DNA components, and [we] were surprised to see that the cells were showing signs of DNA damage in their own DNA. It then occurred to us that we might be exposed to the same forms of damage when we eat food cooked at high temperatures. [So] we started measuring what happens to food DNA when you cook it.”
—Dr. Eric Cool

A paper on their work has been published in ACS Central Science.

The US National Cancer Institute and the American Cancer Society funded part of the research.

In their paper, the researchers explain that they set out to answer three questions with their work:

  • To what extent does cooking damage the DNA of food?
  • Does cell exposure to damaged DNA evoke DNA damage repair responses or chromosomal damage?
  • To what degree is damaged DNA in foods salvaged by the cells of the consumer and incorporated into the consumer’s cellular DNA?

“We cook the food, extract the DNA, and send it to them. We carried out the cell-based studies and mouse studies of DNA damage, and our collaborator at Colorado State University performed additional toxicology studies with us,” Dr. Kool explained to MedicalNewsToday.

For the study, the researchers cooked ground beef, ground pork, and sliced ​​potatoes. The food was cooked by boiling it for 15 minutes at 212 degrees Fahrenheit (100 degrees Celsius) or roasting it for 20 minutes at 428 degrees Fahrenheit (220 degrees Celsius).

The researchers found all three foods showed DNA damage when boiled and roasted. Foods cooked at higher temperatures showed increased DNA damage.

The potatoes sustained less DNA damage than the meat, but researchers weren’t certain of the reason behind this phenomenon. In their paper about the study, they note that plants contain smaller amounts of DNA per weight than animals.

“We were surprised on calculating how much damaged DNA we got exposed to in our diet, particularly with meats, which have high DNA content. It’s a lot. We are all used to thinking about other components of food — carbohydrates, fats, protein, vitamins — but maybe we should start thinking about DNA content too,” Dr. Kool said.

The types of DNA damage sustained by the food were genotoxicwhich means it can impair gene functioning and foster gene mutations that can cause cancer.

The researchers fed the mice a solution that contained heat-damaged DNA components in high concentrations for a week. They then used a tool created in Dr. Kool’s lab that tags sites of damaged DNA with fluorescent molecules. In the mice, the damaged DNA appeared in the cells lining the small intestine.

Additionally, the researchers exposed lab-grown cells to the same solution. The cells showed DNA damage from the uptake of the heat-damaged DNA components.

With their work, the researchers believe that they have shown for the first time that components of food DNA, damaged by being cooked at a high temperature, can be absorbed by a consumer during digestion and incorporated into the DNA of that consumer.

Dr. Sheila David, a chemistry professor at UC Davis in California who studies DNA repair and who was not involved with this research, told MNT the study is significant because “it reveals an additional new mechanism that contributes to the known connection between high-temperature cooking of food [a]and cancer and metabolic disorders.”

Several studies have found that cooking foods at high temperatures may increase health risks. A 2017 studyfor example, found a high intake of grilled, barbecued, or smoked meat may increase mortality after breast cancer.

“We have known that cooking foods at high temperatures, such as grilling meat or allowing it to burn on the grill, can increase our risk for developing certain cancers and increase our risk for other adverse health outcomes and also cause nutrients to be lost, such as as when cooking vegetables at high heat,” Roxana Ehsani, a registered dietitian nutritionist and board certified sports dietitian in Miami, Florida, who was not involved with this study, told MNT.

However, more research will be needed to determine whether this uptake of damaged food DNA occurs in humans. Ehsani pointed out to MNT that evidence already exists suggesting cooking foods at high temperatures poses health risks.

This study serves as “a reminder for people to continue to monitor how long you are cooking your food for and [to] avoid overcooking or cooking foods at high temperatures,” she said.

“I think this adds more evidence, along with the well-established role of other carcinogens in grilled food [t]hat limiting grilled meat is a good idea.”
—Dr. Sheila David

Dr. Kool also took note of the results of his study. “I am eating more vegetables than I used to!” he said.

In their paper, the researchers are careful to note that they don’t discount the idea posed by other researchers that small molecules produced during cooking may also pose genetic risks.

“I also agree that they are a risk, but they are present at very low levels,” Dr. Kool pointed out to MNT.

“Our new study suggests that the DNA itself in the food is also damaged and that it might also pose a risk, and it occurs at much higher levels.”
—Dr. Eric Cool

With future studies, the researchers would like to look at how different cooking methods, temperatures, and cooking times impact the damage to foods’ DNA.

“The authors have opened up an intriguing path for further investigation,” Dr. he said.