Meat's damaged DNA damages your own to raise cancer risk, says study
It’s no secret that red meat and fried foods aren’t great for your health, but Stanford scientists have discovered a new potential mechanism for why. The team found that cooking food at high heat damages its DNA, and that in turn could damage your own DNA, raising the risk of cancer and other health problems.
While red meat has some nutritional value, higher consumption has been linked to increased risk of heart disease, certain cancers, and other chronic illnesses. The WHO classifies it as a Group 2A “probable” carcinogenic, thanks to cancer-causing chemicals and molecules that can form during processing or even cooking. In a new study, scientists at Stanford report a previously unknown potential mechanism by which meat and fried foods could increase a consumer’s cancer risk.
It might not be something we think about, but most food contains DNA – after all, meat, fruit, vegetables, fish, poultry, grains, nuts, mushrooms etc all come from once-living things. And when these foods are cooked at high temperatures, that DNA sustains damage. The researchers on the new study have found that components of this damaged DNA could potentially trigger mutations in the DNA of a consumer.
Other studies have found that charring and/or frying foods can cause DNA damage in consumers, but in those cases the culprit is thought to be damaging molecules called reactive species that form in higher amounts in the body after eating these foods. The researchers on the new study, however, say that the newly discovered mechanism would likely be a bigger driver of DNA damage because nucleotides from our foods’ DNA are more readily incorporated into our own cells during digestion.
“We have shown that cooking can damage DNA in food, and have discovered that consumption of this DNA may be a source of genetic risk,” said Eric Kool, senior author of the study. “We don’t doubt that the small molecules identified in prior studies are indeed dangerous. But what has never been documented before our study is the potentially large quantities of heat-damaged DNA available for uptake into a consumer’s own DNA.”
The team tested their hypothesis on lab-grown human cells and in mice. First, they cooked ground beef, ground pork and potatoes in two different ways – boiling at 100 °C (212 °F) for 15 minutes, or roasting at 220 °C (430 °F) for 20 minutes. Then, they extracted DNA from the foods and examined the damage it had sustained.
They found that the higher temperatures induced higher levels of DNA damage in the food, and that the potatoes took less damage than the meat, for reasons that remain unknown. The two most common types of DNA damage they observed in the samples are known to be toxic in a way that can lead to cancer.
Next, the researchers exposed mice and human cells to the food’s heat-damaged DNA, and used a fluorescent tool to image areas of DNA damage in the recipient cells. And sure enough, they found significant DNA damage in the lab-grown cells, and in the small intestines of the mice.
While the research is intriguing and concerning, the team acknowledges that there’s still plenty of work to be done before this link can be definitively made in humans. The team plans to investigate with a broader range of foods and cooking methods, as well as how long-term low doses, as you’d expect over a real-world lifetime, might affect human health differently than short-term high doses tested in this study.
“Our study raises a lot of questions about an entirely unexplored, yet possibly substantial chronic health risk from eating foods that are grilled, fried, or otherwise prepared with high heat,” said Kool. “We don’t yet know where these initial findings will lead, and we invite the wider research community to build upon them.”
The research was published in the journal ACS Central Science.