August 29, 2012

The Red Meat-Cancer Connection

The link between red meat and cancer is better understood. It is also true that how you cook your meat matters.

Mounting evidence has linked eating red meat to and increased risk of health problems, including cancer – and even to death. Red meat, whether high or low in fat, has been associated with colorectal cancer, and it’s thought that the high iron levels in the meat may be responsible. Now, a new study helps illustrate exactly why this is true.

A gene called the APC is one of the “tumor suppressor” genes in our genomes, meaning that it keeps cells from replicating too much, which is what leads to cancer. But it seems to be highly dependent on the amount of iron present in the body. Researchers at the University of Birmingham found that when the APC gene was fully functional in mice, the animals did not develop intestinal cancer, even when fed diets high in iron.

But it’s not just the amount of meat (or iron) in your diet that can affect cancer risk. The way you cook meat also matters.

But when the APC gene is turned off, the mice did develop tumors, after iron levels increased in their bowels. Interestingly, when mice were fed a diet lacking iron, cells that had faulty APC genes were destroyed and the mice did not develop tumors. Therefore, it seems that a combination of genes (APC) and environment (dietary iron) is responsible for whether or not an animal (and likely, a person) develops colorectal cancer.

The authors are encouraged by their results, which finally help explain some of the connections we’ve seen for so long. "We're now planning to develop treatments that reduce the amount of iron in the bowel and so could lower the risk of developing bowel cancer,” said author Chris Tselepis in a news release. “We hope to start using these in trials in the next few years in people who are at a greater risk."

But it’s not just the amount of meat (or iron) in your diet that can affect cancer risk. The way you cook meat also matters, as earlier studies have also suggested, in the development of another kind of cancer: Prostate cancer. Another new study from the University of Southern California reports that men who ate pan-fried meat at least 1.5 times per week were 30% more likely to have advanced prostate cancer (that which has spread to other parts of the body) than men who rarely ate it. Even more, men who ate meat cooked by any type of high-temperature method, like grilling or broiling, were 40% more likely to develop advanced prostate cancer than men who rarely did.

Interestingly, there was no connection between red meat and prostate cancer until cooking methods were brought into the mix. It’s believed that cooking at higher temperatures increases one’s cancer risk because carcinogens like polycyclic aromatic hydrocarbon (PAHs) and heterocyclic amines (HCAs) form in greater quantities during high-heat cooking methods.

More research will of course be needed to determine all the connections between red meat, cooking methods, iron levels, and the risk of cancer of various forms. But while new studies are underway, it can’t hurt to cut down on your consumption of red meats cooked under high temperatures or charred in the process – or at least marinate them before you cook them.

The first study was published in the journal Cell, the second in Carcinogenesis.

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