Don’t Let That Steak Tempt You

Eating red meat has gotten a poor reputation among cardiologist, and a few years ago, a report came out linking grilled red meat—especially well done—with the risk of developing prostate cancer. It was demonstrated that cooking meat over an open flame and charring it at high temperatures causes two chemicals, HCAs and PAHs, to form. These chemicals have been linked with prostate cancer development in animal studies.

New research has revealed that there’s something about beef itself, as well as pork, lamb and bison, that poses a cancer danger. It’s a non-human sugar molecule called Neu5Gc (N-glycolylneuraminic acid) that is found not only in these meats, but also in whole milk, some cheeses and fish eggs (not in fish itself). Humans evolved out of the ability to produce this molecule, but other mammals still need it to help the immune system distinguish between “self” and “alien” cells. Because of the way the molecule is formed, it is incorporated into human tissues. It is especially absorbed in cells that have a rapid growth rate such as fetuses, epithelial and endothelial tissue, and tumors. Once there, the immune system detects and registers it as a foreign invader. It attacks it, resulting in an inflammatory reaction.

The research team from University of California, San Diego was led by Dr. Arjit Varki, a professor of cellular and molecular medicine at UCSD. Dr. Varki hypothesizes that the molecule does not necessarily cause cancer, but may fuel its growth “like gasoline on the fire.”[i] His team’s study, published in the Proceedings of the National Academy of Sciences, sheds light on why there may be a connection between eating red meat and an increased risk of various cancers, including prostate cancer. Neu5Gc may not itself be a carcinogen (cancer-causing substance) but the chronic inflammation caused by the body’s efforts to get rid of it may play a role in accelerating a cancer’s development.

Dr. Varki’s team tested their theory on mice that were genetically engineered to be unable to produce Neu5Gc, just as humans are unable to do. When fed a diet high in Neu5Gc, their cancer rate was five times greater than that of control animals. One possible solution would be for cattle producers to breed selectively for cattle whose cells do not contain the molecule, assuming that Neu5Gc is indeed the culprit. It is noteworthy that consuming chicken and fish is not associated with heightened cancer risk, and these animals have very little or no Neu5Gc. The idea that grilling and charring red meat is carcinogenic is not borne out by grilling and charring either chicken or fish, which causes the meat to produce the same chemicals as grilling beef—but without a carcinogenic effect.

Dr. Varki recognizes that red meat contains important nutrients, such as iron. He does not recommend that people stop eating red meat (though he himself does not) but he does encourage people over age 40 to consider cutting down.

So the next time you’re in the meat section of your local grocery, think about walking away from beef, lamb, pork and bison and picking up some chicken or fish instead. It could be in your prostate’s best interest.

 

 


[i] http://www.utsandiego.com/news/2014/dec/29/red-meat-cancer-varki-neu5Gc-sialic/