Grilled meat’s link to cancer bolstered

These still-hot evenings are prime time for grilling. But some research suggests that this all-American ritual carries health risks beyond the long known hazard of setting yourself on fire.

At high temperatures or over open flames, this research suggests, compounds in red and processed meats undergo biochemical reactions that produce carcinogenic compounds capable of altering the eater’s DNA.

Most of the research has been conducted in lab dishes and in animals. But new evidence connects the dots to human risks of cancer, too.

Does that mean we ought to give up meat — or grilling — altogether? Grilled vegetables don’t harbor the same risks, and there are ways to cook meat that produce fewer of the suspect chemicals.

Sources consulted for this article said moderation is probably fine.

“You can just Google and see all of these sensationalistic headlines that say eating bacon is like smoking a pack of cigarettes,” but it’s not the same, says Robert Turesky, a biochemical toxicologist at the University of Minnesota, Minneapolis. “I still do enjoy barbecue. I just don’t eat it as often.”

The case for meat as a cancer risk has been building for decades, with studies finding that people who report eating diets heavy in red and processed meats have higher risks of some cancers as well as heart disease and other illnesses. Enough of those studies — together with still unpublished lab work — have built up to make a convincing case that meat carries risks, according to a 2015 analysis by the World Health Organization’s International Agency for Research on Cancer, which considered more than 800 studies conducted around the world.

Overall, the agency review found that the strongest evidence linked processed meats (such as hot dogs, beef jerky, bacon and ham) to colorectal cancer — with each hot-dogsize serving of processed meat eaten daily raising the risk by 18 percent over a lifetime.

More than 34,000 cancer deaths are caused around the world each year by diets high in processed meat, according to data referenced in the report. By comparison, tobacco causes about a million cancer deaths annually. Alcohol consumption causes 600,000. And air pollution is responsible for 200,000.

The agency’s review also found evidence for an association between unprocessed red meat (such as beef or pork) and colorectal cancer, along with some evidence that red meat might contribute to pancreatic and prostate cancers, too.

Studies show several ways that meat might cause cancer, says Loic Le Marchand, an epidemiologist at the University of Hawaii Cancer Center, who collaborated with more than 20 international scientists on the agency report. One line of evidence points to compounds called nitrates and nitrites, which are used during processing and also form in the colon when people digest meat and meat products, even those labeled “nitrate-free.”

WELL DONE?

Cooking methods make a difference, according to studies that have zeroed in on two groups of chemicals that appear in particularly large quantities when meat, fish or poultry is cooked under high heat by grilling, barbecuing, boiling or even pan-frying.

One group, called heterocyclic aromatic amines (HAAs), form during high-temperature reactions between substances in muscle tissue. Polycyclic aromatic hydrocarbons (PAHs), which form when meat is smoked, charred or cooked over an open flame, are also found in tobacco smoke.

In general, Turesky says, higher temperatures and longer cooking times lead to higher levels of HAAs and PAHs. Enzymes in our bodies then change these chemicals into compounds that can damage DNA. Many studies have illustrated that kind of damaging potential in cell cultures and animals, including rodents and primates.

But does meat actually cause cancer in people?

Turesky sees evidence that it might. In a study published last year, he and colleagues studied biopsies of prostate tumors and found that DNA in the cancer cells had been damaged by HAAs.

“This is the first unequivocal proof that, once you eat the cooked meat mutagens, some of them find their way to the prostate and damage the prostate,” Turesky says.

The study doesn’t prove that chemicals in the cooked meat caused the cancer, he adds. “It could just be an association.”

JUST IN CASE

In the meantime, research suggests several ways to lower levels of carcinogens in your meat.

■ Marinating before cooking helps keep the surface of the meat from getting so hot, Turesky says.

■ Microwaving before barbecuing can also help.

■ So can flipping burgers frequently and taking care not to char or burn meat while also cooking it enough to avoid the more immediate health risks of eating uncooked meat.

Eating meat once in a while won’t cause cancer, Le Marchand says. It’s regular and repeated exposure for decades that is suspected of being harmful.