Processed red meat has been found to be as dangerous as cigarettes, arsenic and asbestos. In October 2015, the reputable World Health Organization issued a two-thumbs down report about red and/or processed meats, placing them into the highest categories of carcinogens. Its agency for Research on Cancer released findings that red and processed meats are probably carcinogenic. This finding was observed mainly for colorectal cancer, but clear associations were also seen for pancreatic cancer and prostate cancer. The WHO study confirmed previous studies showing a clear connection between eating red meat and an increase the risk for some cancers. The WHO went a bit further, designating processed meat the highest carcinogenic risk rating — a category that includes alcohol, asbestos, arsenic and cigarettes — and red meat the second-highest one. Yet, until recently, scientists haven’t been able to explain why red meat causes cancer. However, culprit may be a sugar molecule called Neu5Gc, found in beef, pork and lamb.
The link between cancer and red meat has been known for decades. After a systemic review of scientific studies, an expert panel of the World Cancer Research Fund and the American Institute for Cancer Research concluded in 2007 that “red or processed meats are convincing or probable sources of some cancers.” Their report showed evidence of a link between red meat, processed meat, and colorectal cancer, and limited but suggestive for links to lung, esophageal, breast, prostate, stomach, pancreatic, and endometrial cancers. And a clear link to colon cancer was confirmed by two 2005 studies that showed that the risk of colon cancer increased by over 30% for red meat eaters. These studies were affirmed by the WHO report, referenced above. However, no authoritative study has explained why red meat consumption appears to trigger cancer.
But the elusive link between cancer and red meat may have been finally revealed in a study at the University of California, San Diego School of Medicine published in the Dec. 29 online early edition of the Proceedings of the National Academy of Sciences. In this study, the scientists found that feeding Neu5Gc to mice engineered to be deficient in the sugar (like humans) significantly promoted spontaneous cancers. They claim that this is first time scientists have directly shown that mimicking the exact situation in humans – feeding non-human Neu5Gc and inducing anti-Neu5Gc antibodies – increases spontaneous cancers in mice. The study did not involve exposure to carcinogens or artificially inducing cancers, further implicating Neu5Gc as a key link between red meat consumption and cancer.
The researchers theorize that when you consume red meat, the body sees it as a foreign substance – and the immune system attacks it. This leads to inflammation in the body, which over time is known to promote the formation of tumors. The research indicates that dairy products contain this same suspect sugar molecule. Neu5Gc naturally occurs in most mammals but not humans, this also explains why humans are more at risk cancer while other carnivores are not.
For red meat consumers, this new study suggests that long-standing warnings about reducing consumption of red meat may have more merit than had been previously thought. Red meat — and especially processed red meat such as bacon, sausage, hot dogs or other smoked, salted, cured meats — were found to substantially increase the risk of colorectal cancer. The WHO study found that each 50 gram portion of processed meat eaten daily (1/10 of a pound or the equivalent of two slices of bacon) increases the risk of colorectal cancer by 18%. This bodes poorly for Americans who eat, on average, 71 pounds of red meat annually.
The body’s response to the Neu5Gc molecule appears to be causing inflammation which leads to cancer causation. This molecule is not found in poultry or fish, so those meats appear to be safer to consume. Few would deny that red meat tastes great but it is becoming clearer that it may be better as an occasional splurge than a staple of one’s diet.