Researchers, who sought answer for why people who eat a lot of red meat are at higher risk for certain cancers while people who eat other types of meat are not, found that it is due to a non-human sugar present in red meat that promotes inflammation and cancer progression in rodents.
The team was led by an Indian-origin researcher at the University of California, San Diego. After conducting a systematic survey of common foods, the scientists found that found that red meats – beef, pork and lamb – are rich in a sugar called Neu5Gc and provide the primary sources of this sugar in the human diet.
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. Neu5Gc is found naturally in most mammals but not in humans.
The principal investigator Ajit Varki, distinguished professor of medicine and cellular and molecular medicine at University of California, said, “Until now, all of our evidence linking Neu5Gc to cancer was circumstantial or indirectly predicted from somewhat artificial experimental set ups.”
During the study, the team engineered mice to mimic humans in that they lacked their own Neu5Gc and produced antibodies against it. When these mice were fed Neu5Gc, they developed systemic inflammation. Spontaneous tumor formation increased fivefold and Neu5Gc accumulated in the tumors.
Adding, he said, “This is the first time we have directly shown that mimicking the exact situation in humans – feeding non-human Neu5Gc and inducing anti-Neu5Gc antibodies – increases spontaneous cancers in mice.”
Researchers found that red meats are rich in Neu5Gc, affirming that foods of mammalian origin such as these are the primary sources of Neu5Gc in the human diet.
The molecule was found to be bio-available too, meaning it can be distributed to tissues throughout the body via the bloodstream. Meanwhile, the researchers had previously discovered that animal Neu5Gc can be absorbed into human tissues.
In this study, they hypothesised that eating red meat could lead to inflammation if the body’s immune system is constantly generating antibodies against consumed animal Neu5Gc, a foreign molecule.
“This work may also help explain potential connections of red meat consumption to other diseases exacerbated by chronic inflammation, such as atherosclerosis and type 2 diabetes,” Varki said.