1244 GMT November 12, 2019
In the study, the scientists found that feeding Neu5Gc to mice engineered to be deficient in the sugar (like humans) significantly promoted spontaneous cancers. 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, Medical Daily said.
"Until now, all of our evidence linking Neu5Gc to cancer was circumstantial or indirectly predicted from somewhat artificial experimental setups," said principal investigator Ajit Varki, MD, member of the UC San Diego Moores Cancer Center. "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."
Varki's team first conducted a systematic survey of common foods. They 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.
The researchers had previously discovered that animal Neu5Gc can be absorbed into human tissues. In this study, they hypothesized 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. Chronic inflammation is known to promote tumor formation.
To test this hypothesis, 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.